Virology Final 2014

Front 1

The main advantage of using virus isolation over the molecular based diagnostic assays such as PCR is that:

a) Virus isolation is quicker than PCR.
b) Virus isolation is cheaper than PCR.
c) Virus isolation requires less sophisticated equipment and fewer skills than more advanced tests such as PCR.
d) Unlike PCR, virus isolation demonstrates the presence of live virus in the sample.
e) Unlike PCR, virus isolation provides immediate definitive identification of the virus, based upon the type of a cytopathic effect (CPE) produced in cell culture.

Back 1

d) Unlike PCR, virus isolation demonstrates the presence of live virus in the sample.

PCR tests for the presence of specific nucleotide sequences while virus isolation tries to grow the live virus.

Front 2

Which of these stages in the viral replication cycle is least likely to be targeted by antiviral drugs?

a) Adsorption.
b) Attachment.
c) Uncoating.
d) Synthesis.
e) Release.

Back 2

a) Adsorption.

Adsorption consists of the nonspecific binding of virus particles to cell membranes. This stage is not targeted by antivirals because it is nonspecific (you can't really prevent particles from randomly bumping into each other).

Front 3

Viruses posses the following characteristics:

a) Viruses contain both DNA and RNA.
b) The viral nucleic acids are enclosed within the nucleus inside the viral particle.
c) The viral nucleic acids are used to generate viral mRNA within the host cell.
d) Viruses contain ribosomes, which are released into the host cell and used for viral protein synthesis.
e) All viruses can be cultured in vitro in the appropriate cell culture system.

Back 3

c) The viral nucleic acids are used to generate viral mRNA within the host cell.

All other choices are false (E could be true). All viral DNA or RNA needs to be converted into mRNA so that the sequence can be read by the host cell.

Front 4

Choose the leastcorrect statement regarding the attachment of the virus to the host cell:

a) Attachment is necessary for viral entry into the cell.
b) Attachment step is one of the important determinants for viral tissue tropism and host range.
c) Attachment relies on specific binding between viral and host proteins.
d) Attachment is immediately followed by penetration of the virus into the host cell.
e) Attachment step cannot be blocked as viruses typically use a wide variety of host receptors for attachment and entry.

Back 4

e) Attachment step cannot be blocked as viruses typically use a wide variety of host receptors for attachment and entry.

All other choices are true. The attachment step relies on the presence of specific receptors which is why many viruses are species specific.

Front 5

The term "viral virulence" relates to:

a) The ability of the virus to cause disease in its natural host species.
b) The ability of the virus to cause cytopathic effects (CPE) in cell culture.
c) The ability of the virus to cause disease in humans.
d) The ability of the virus to spread systemically and infect a variety of tissues.
e) The ability of the virus of cause disease in a specified host.

Back 5

e) The ability of the virus of cause disease in a specified host.

This is the definition of virulence.

Front 6

Choose the best answer to finish the sentence: Swabs for virological investigation should be collected...

a) Into a commercially available aerobic bacteriological swab -the medium provided with these swabs is suitable for both viral and bacteriological samples.
b) Into a commercially available anaerobic bacteriological swab -the medium provided with these swabs is suitable for both viral and bacteriological samples.
c) Dry into a sterile container (e.g. red top blood tube), so that any viruses present will not be diluted by the medium.
d) Into a viral transport medium, which contains proteins to stabilize the virus and antibiotics to prevent bacterial growth.
e) Into a sterile EDTA blood tube if the swab contains bloody discharge, so that it won't coagulate during transport to the laboratory.

Back 6

d) Into a viral transport medium, which contains proteins to stabilize the virus and antibiotics to prevent bacterial growth.

Placement into a viral transport medium is the only appropriate collection method for virological investigation.

Front 7

The samples for virological investigation should be transported to the laboratory:

a) As soon as possible, preferably within 24 hours of collection. The samples should be put in a freezer immediately after collection and then thawed when ready for transport. The samples should be transported cold with ice packs.
b) As soon as possible, preferably within 24 hours of collection. The samples should be kept cold, but not frozen after collection and during transport.
c) Within a week of collection, providing they are kept in a fridge.
d) As soon as possible, preferably within 24 hours of collection. If the samples are transported to the laboratory soon after collection there is no need to maintain the cold chain during transport.
e) Any time after collection as long as the samples are maintained in the fridge. If the samples were collected using sterile technique all viruses will survive in the fridge for extended periods of time.

Back 7

b) As soon as possible, preferably within 24 hours of collection. The samples should be kept cold, but not frozen after collection and during transport.

All other choices are not appropriate.

Front 8

Which of the following statements about virus size and complexity is most true?

a) The smallest viruses are smaller than viroids.
b) The largest viruses are about as complex as Escherichia coli.
c) The largest viruses can replicate independently of living cells.
d) The smallest viruses consist only of protein.
e) The smallest viruses are larger than prions.

Back 8

e) The smallest viruses are larger than prions.

All other choices are false. A prion can be a single protein in a misfolded form while viruses are composed of multiple proteins (and are therefore larger).

Front 9

Which of the following is least usefulas a basis for classifying viruses into families?

a) DNA or RNA genome.
b) Double-stranded or single-stranded genome.
c) Intranuclear or intracytoplasmic inclusion bodies.
d) Helical, icosahedral, or complex structural symmetry.
e) Enveloped or non-enveloped virions.

Back 9

c) Intranuclear or intracytoplasmic inclusion bodies.

All other choices are characteristics used to classify viruses into families. The use of inclusion bodies to classify viruses into families is less useful as the presence of inclusion bodies may vary below the family level.

Front 10

Which of the following stages in the virus replication cycle is the drug Tamiflu thought to target?

a) Adsorption.
b) Attachment.
c) Uncoating.
d) Synthesis.
e) Release.

Back 10

e) Release.

Tamiflu (Oseltamivir) is a neuriminidase inhibitor which slows the spread of influenza virus between cells by preventing the release of viral particles.

Front 11

Soluble CD4 has been used experimentally as an anti-HIV drug and may yet prove useful in veterinary medicine. Which of the following stages in the virus replication cycle is it thought to target?

a) Adsorption.
b) Attachment.
c) Uncoating.
d) Synthesis.
e) Release.

Back 11

b) Attachment.

The attachment stage of HIV may be blocked by CD4 derivaties (i.e. receptor analogues or antagonists).

Front 12

Which of the following is the most commonly and widely used method for the cultivation of mammalian viruses?

a) Organ cultures.
b) Experimental animals.
c) Primary cell cultures.
d) Secondary cell cultures.
e) Continuous cell lines.

Back 12

e) Continuous cell lines.

Cultivation in cell cultures is the most commonly used method, continuous cell lines are used for most tissue culturing as they can be passaged indefinitely, these are often derived from neoplastic tissue.

Front 13

A cytopathic effect (CPE) is sometimes observed when cultivating viruses in vitro. Which of the following statements about CPE is least correct?

a) Some kinds of virus cause a characteristic CPE. For example, herpesviruses tend to cause formation of syncytia.
b) Dead cells, killed by the virus, tend to look large, angular, and paler than surrounding healthy, uninfected cells.
c) It may take weeks for a CPE to develop. Multiple cell passages may have to be done before CPE can be observed.
d) Some kinds of virus grow very well in cell culture but cause no CPE whatsoever.
e) If CPE develops very rapidly, it may be difficult to distinguish it from cytotoxicity due to a toxic substance in the clinical specimen (i.e., the inoculum).

Back 13

e) If CPE develops very rapidly, it may be difficult to distinguish it from cytotoxicity due to a toxic substance in the clinical specimen (i.e., the inoculum).

All other choices are true.

Front 14

Which of the following are viral non-structural proteins? Choose all correct answers (there may be more than one).

a) Integrase.
b) Reverse transcriptase.
c) Hyaluronidase.
d) Hexokinase.
e) Peplomerase.

Back 14

a) Integrase.
b) Reverse transcriptase.

C is an enzyme involved in fertilisation, D is an enzyme involved in glycolysis, and E does not exist.

Front 15

Which of the following statements about viral structure are true? Choose all correct answers (there may be more than one).

a) Structural symmetry facilitates virion self-assembly.
b) Cubic symmetry is a synonym for icosahedral symmetry.
c) Individual virus families contain viruses of helical or icosahedral symmetry, but not both.
d) Virions with complex symmetry have both helical and icosahedral symmetry.
e) Helical symmetry is a feature of the viral nucleocapsid, not of the envelope.

Back 15

a, b, c, e

D is not true as complex symmetry is neither helical or icosahedral.

Front 16

Laboratory results of virus isolation are usually available:

a) Within 24-48 hours. This is how long it takes for viral colonies to become visible on agar plates.
b) Within 2-3 days for positive samples, but it may take up to 1 week for negative samples, as these are typically passaged in the appropriate cells 2-3 times before being reported as negative.
c) Within 1-3 weeks for positive samples, but it may take up to one month or longer for negative samples, as these are typically passaged in the appropriate cells 2-3 times before being reported as negative.
d) Within 24-48 hours, as viruses multiply very fast and typically millions of viruses are produced from one infected cell within hours.
e) Within 1 week for negative samples, but it may take longer for positive samples, as the viruses cultured would have to be further identified.

Back 16

c) Within 1-3 weeks for positive samples, but it may take up to one month or longer for negative samples, as these are typically passaged in the appropriate cells 2-3 times before being reported as negative.

It may take up to 3 weeks for cytopathic effects to become evident. Samples are typically passaged 2-3 times.

Front 17

Which of the following statements about viral genomes is least true?

a) Most DNA virus families have double-stranded genomes.
b) Some RNA viruses have segmented genomes, but there are no DNA viruses with segmented genomes.
c) There are no known RNA viruses with circular genomes.
d) DNA virus genomes vary in size much more than do RNA virus genomes.
e) There are no known RNA viruses with double-stranded genomes.

Back 17

c) There are no known RNA viruses with circular genomes.

All other choices are true. Hepatitis D virus is one example of an RNA virus with a circular genome.

Front 18

Antiviral drugs inhibit specific steps in viral replication.

Back 18

T

All antiviral drugs act on one of six viral replication steps (no drugs prevent adsorption).

Front 19

Resistance to antiviral drugs is very rare, as viruses cannot change as rapidly as bacteria.

Back 19

F

Viruses can change much more quickly than bacteria which may lead to antiviral resistance.

Front 20

Enveloped viruses are typically fragile and easily killed outside their hosts.

Back 20

T

Viral envelopes are derived from the membranes of infected host cells, these membranes are not meant to be exposed to the external environment.

Front 21

Killed vaccines are safer and as such, killed vaccines are more commonly used in veterinary medicine than live vaccines.

Back 21

F

Killed vaccines are not necessarily safer as they need to be paired with adjuvants. Live vaccines are cheaper which is often an important consideration in veterinary medicine.

Front 22

A single serum sample positive for antibody to a virus indicates that the animal from which the blood was collected had been recently infected with this virus.

Back 22

F

A single serum sample gives no information about the timing of the infection, it only tells us that the animal was exposed to virus in the past. A fourfold rise in titre between acute and convalescent samples suggests recent infection.

Front 23

A large sheep farm in central Otago has had problems with scabby mouth in lambs each year for the last 4 years. They do not vaccinate against scabby mouth on this farm. The most likely explanation for the recurrent, relatively severe problems on this farm is:

a) Persistently-infected ewes are acting as a source of the virus to new lambs each year.
b) The virus is maintained in a rodent population on this farm and is periodically spread to lambs.
c) Rams are transmitting the virus venereally to ewes and the ewes are passing the infection on to their lambs.
d) The pastures and food troughs are contaminated with the virus, which is surviving outside each winter
e) An unusually hardy virus variant has evolved on this farm.

Back 23

d) The pastures and food troughs are contaminated with the virus, which is surviving outside each winter

Poxviruses are able to survive for long periods in the external environment.

Front 24

Which of the following viruses typically produce only localised infections without systemic spread:

a) Feline panleukopenia virus.
b) Equid herpesvirus type 1.
c) Canine parvovirus.
d) Orf virus.
e) African swine fever virus.

Back 24

d) Orf virus.

All other choices are capable of producing generalised infection.

Front 25

Which of the following viruses infect invertebrate hosts?

a) African swine fever virus.
b) Canine adenovirus type 1.
c) Feline herpesvirus type 1.
d) Orf virus.
e) Porcine circovirus type 2.

Back 25

a) African swine fever virus.

As an arbovirus, African swine fever virus replicates within an invertebrate host (a soft tick).

Front 26

A proliferative lesion in the picture below is characteristic of infection with:

a) Herpesviruses.
b) Adenoviruses.
c) Poxviruses.
d) Circoviruses.
e) Parvoviruses.

Back 26

c) Poxviruses.

The development of small lesions that balloon and combine to become a large wart-like scab (seen in the picture) is characteristic of poxviruses.

Front 27

In general, poxviruses can use the following portals of entry:

a) Faecal-oral route.
b) Skin with compromised integrity (e.g. skin abrasions).
c) Respiratory route (via aerosols).
d) Blood via mechanical vectors.
e) Portals listed in b, c, or d.

Back 27

e) Portals listed in b, c, or d.

Poxviruses spread mainly through skin abrasions, but also through mechanical vectors (i.e. lice with swinepox) or aerosols (i.e. sheep pox).

Front 28

The fish in the picture below is most likely infected with:

a) A fish herpesvirus.
b) An asfarvirus.
c) A circovirus
d) An iridovirus.
e) A poxvirus.

Back 28

d) An iridovirus.

Lymphocystis (caused by an iridovirus) causes tumour-like lesions on the skin and fins of fish.

Front 29

You are a veterinarian accompanying a large group of sheep that is being shipped from New Zealand to the Middle East in a vessel that has previously been used for the shipment of sheep in other parts of the world. 28 days into the journey, 20% of these sheep have developed fever, generalised, raised skin lesions, and severe systemic illness. So far, about 25% of affected animals have died or required euthanasia on humane grounds. You suspect a viral infection. The most likely differential diagnosis at this stage is:

a) Generalised orf.
b) Ectromelia.
c) Variola.
d) Contagious ecthyma.
e) Sheep pox.

Back 29

e) Sheep pox.

These signs are consistent with sheep pox infection. Sheep pox would be expected to cause high mortality in New Zealand sheep and ships used to transport sheep from New Zealand and then return are a potential method of entry into New Zealand for the virus.

Front 30

What kind of vaccine is licensed in New Zealand to prevent Orf?

a) Modified live (i.e., attenuated).
b) Adjuvanted, killed whole virus.
c) Adjuvanted, viral subunit.
d) Live, fully virulent virus.
e) Recombinant avipox virus.

Back 30

d) Live, fully virulent virus.

Orf vaccine consists of a live, fully virulent virus, which is applied to lambs by scarification of the inside of the thigh at 1 and 3 months of age.

Front 31

Which of the following poxviruses has an unusually broad host range?

a) Myxoma virus.
b) Lumpy skin disease virus.
c) Variola virus.
d) Swinepox virus.
e) Cowpox virus.

Back 31

e) Cowpox virus.

Most poxviruses are highly host specific, but cowpox has a broad host range.

Front 32

You are called to investigate a drop in production levels at a local poultry farm. When you arrive, you notice a large number of misshapen eggs, as shown in a picture below. Infection with which virus should be on your list of differentials?

a) Poxvirus.
b) Adenovirus.
c) Parvovirus.
d) Herpesvirus.
e) Circovirus.

Back 32

b) Adenovirus.

The image shows eggs affected by egg drop syndrome, an adenovirus which causes birds to produce weak or thin-shelled eggs.

Front 33

Which of the following are characteristic features of poxviruses? Choose all correct answers (there may be more than one).

a) Enveloped DNA viruses.
b) Intracytoplasmic replication.
c) Long-term carrier state after recovery.
d) Evolve more rapidly than most other viruses.
e) Complex structural symmetry.

Back 33

a, b, e

C occurs with adenoviruses, D occurs with orthomyxoviruses (influenza). Note that B is unusual for DNA viruses but is a unique characteristic of poxviruses.

Front 34

Which of the following poxviral diseases is not known to be zoonotic? Choose all correct answers (there may be more than one).

a) Cowpox.
b) Pseudocowpox.
c) Bovine papular stomatitis.
d) Parapoxvirus infection of red deer in New Zealand.
e) Monkeypox.

Back 34

d) Parapoxvirus infection of red deer in New Zealand.

All other choices are zoonotic.

Front 35

Which of the following is the least important reason why it was possible to eradicate smallpox from the world?

a) ONE (1) stable serotype of the virus exists.
b) Smallpox has a long incubation period.
c) Animal reservoir populations are well characterised.
d) Smallpox is easily diagnosed.
e) The period of infectivity begins after the end of the incubation period.

Back 35

c) Animal reservoir populations are well characterised.

All other choices are true.

Front 36

Which of the following viruses is least resistant to adverse environmental conditions:

a) Canine parvovirus.
b) Equid herpesvirus type 1.
c) Orf virus.
d) African swine fever virus.
e) Bovine papillomavirus.

Back 36

b) Equid herpesvirus type 1.

Herpesviruses are very fragile in the environment. All other choices are very resistant.

Front 37

Orf virus can be transmitted between susceptible animals via fomites.

Back 37

T
Orf is spread by direct contact and fomites.

Front 38

Poxviruses typically cause localized skin infections.

Back 38

T
Poxviruses typically cause skin lesions or "pocks" hence the name poxvirus.

Front 39

Some poxviruses can establish viremia followed by generalized disease.

Back 39

T
Viraemia can occur in several types of poxviruses (i.e. cowpox, sheep pox, fowl pox, etc.)

Front 40

Poxviruses do not survive well in the environment.

Back 40

F
Poxviruses can survive for years in dust or scabs.

Front 41

Orf virus can infect humans.

Back 41

T
Orf is considered zoonotic.

Front 42

Myxomatosis causes severe generalised disease in European rabbits, but only localised benign fibromas in American rabbits.

Back 42

T
Local fibromas occur in American rabbits while severe, generalised disease is seen in European rabbits.

Front 43

Choose the least true statement regarding the African swine fever (ASF) virus:

a) In Africa, the virus is maintained in the wild hog populations without any overt clinical disease.
b) The immune response to the virus is unusual in such there is no production of neutralising antibodies, even in survivors.
c) It causes a highly contagious lethal disease of domestic pigs.
d) Recovered animals have long-term resistance to disease, however they remain life-long carriers.
e) It is a fragile virus, which does not survive well outside its host. Direct contact with live infected pigs or ticks is necessary for infection.

Back 43

e) It is a fragile virus, which does not survive well outside its host. Direct contact with live infected pigs or ticks is necessary for infection.

ASF is highly resistant to a wide range of pH (4 to 15) and can survive for months to years in refrigerated meat.

Front 44

The most likely route of entry to New Zealand for African swine fever virus is:

a) Through infected mosquitoes.
b) Through infected carrier animals that do not display any clinical signs such as
sheep.
c) Through infected, frozen pig meat.
d) Through infected ticks.
e) Through contaminated farm equipment.

Back 44

c) Through infected, frozen pig meat.

Infected frozen pig meat is the most likely route of entry as ASF can survive for prolonged
periods of time in refrigerated/frozen meat.

Front 45

Which of the following statements about African swine fever virus is untrue?

a) It is fragile in the environment, relying on intimate contact for transmission.
b) It is the only DNA virus biologically transmitted by arthropods.
c) Its natural hosts are wild pigs and ticks.
d) It is not closely related to any other virus of veterinary importance.
e) No commercial vaccine is yet available.

Back 45

a) It is fragile in the environment, relying on intimate contact for transmission.

All other choices are true. African swine fever virus is highly resistant to a wide range of pH (4 to 15) and can survive for months to years in refrigerated meat.

Front 46

African swine fever virus is the only DNA virus that is also an arbovirus.

Back 46

T
African swine fever is the only DNA virus that is also an arbovirus. It replicates within and is transmitted by soft ticks.

Front 47

African swine fever virus is present only in Africa.

Back 47

F
African swine fever can sometimes affect Europe as well as Africa.

Front 48

An outbreak of African swine fever virus can be successfully controlled by ring-vaccination.

Back 48

F
No vaccination exists for African swine fever.

Front 49

You are called to investigate an abortion "storm" that is occurring in a mob of pregnant mares. On close questioning, you learn that several horses have also been recently showing signs of respiratory disease. You also learn that the "colds" and abortions seem to have started soon after two of the mares had been inseminated with semen from a Standardbred stallion that had not been used by the owners before. Which of the following causes should be on the top of your differential list?

a) Equid herpesvirus type 4.
b) Equine arteritis virus.
c) Equine adenovirus.
d) Equine herpesvirus type 2.
e) Equine rhinitis virus.

Back 49

b) Equine arteritis virus.

Herpesviruses can cause abortions as well, but arteritis is often transmitted by semen as male stallions can shed the virus in semen for long periods of time without showing any clinical signs.

Front 50

A kitten with upper respiratory disease is most likely to be infected with which of the following viruses:

a) Feline immunodeficiency virus.
b) Feline herpesvirus.
c) Feline coronavirus.
d) Feline astrovirus.
e) Feline infectious peritonitis virus.

Back 50

b) Feline herpesvirus.

The viruses most commonly associated with feline respiratory disease are feline calicivirus (FCV) and feline herpesvirus-1 (FHV-1). Coronavirus and astrovirus cause diarrhoea in cats. FIV and FIP target immune cells in cats.

Front 51

Choose the least correct statement regarding Pseudorabies:

a) It is caused by Suid herpesvirus type 1.
b) In dogs, it presents with clinical signs similar to rabies with incoordination, paralysis and convulsions.
c) Adult swine infected with the Pseudorabies virus typically do not develop severe disease, but may abort.
d) Dogs can become infected via ingestion of infected raw pig meat.
e) It is a zoonotic disease.

Back 51

e) It is a zoonotic disease.

Pseudorabies can be seen in pigs (reservoir host), cattle, dogs, and cats but does not infect humans.

Front 52

Which of the following viruses is least likely to cause neurologic disease in a horse?

a) Equid herpesvirus type 4.
b) Equid herpesvirus type 1.
c) Borna disease virus.
d) Eastern equine encephalitis virus.
e) Feline infectious peritonitis virus.

Back 52

e) Feline infectious peritonitis virus.

FIP does not affect horses and even if it did, FIP targets macrophages rather than neural cells.

Front 53

Which of the following viruses is least likely to cause neurologic disease in a horse?

a) Equid herpesvirus type 1.
b) Borna disease virus.
c) Western equine encephalitis virus.
d) Equine influenza virus.
e) West Nile virus.

Back 53

d) Equine influenza virus.

All other choices cause neurologic disease. Equine influenza typically infects the respiratory tract. Clinical disease causes pyrexia, depression, loss of appetite, a repeated dry cough at rest, and enlarged submandibular lymph nodes but no neurologic signs.

Front 54

One of the characteristics common to all herpesviruses is their ability to establish latency in their hosts. Choose the best statement describing the relationship between the host and a herpesvirus in a latent stage:

a. During latency there is a very limited production of progeny viruses.
b. During latency there is no production of progeny viruses, but limited transcription of the viral genome can occur.
c. All herpesviruses establish latency exclusively in neural tissues.
d. Once the virus enters a latent stage, it can be reactivated only if the host becomes re-infected with the same herpesvirus.
e. Vaccination against herpesviruses is typically effective in preventing development of latency.

Back 54

b. During latency there is no production of progeny viruses, but limited transcription of the viral genome can occur.

Latency refers to a state in which the viral genome is present in an animal's body but only a few (if any) genes are transcribed and there is no production of infectious virus.

Front 55

Choose the best option from the following. Herpesviruses:

a. Typically cause a short illness followed by recovery and elimination of the virus.
b. Stimulate solid (possibly life-long) immunity. Recovered animals are refractory to subsequent herpesviral infections.
c. Establish a life-long infection in their hosts, with a constant low-level production of infectious virus.
d. Are very resistant in the environment and as such, are easily transmitted by fomites over extended areas.
e. Typically establish a life-long infection due to their ability to become latent.

Back 55

e. Typically establish a life-long infection due to their ability to become latent.

All other choices are false. Latency is a characteristic feature of herpesviruses.

Front 56

Which of the following clinical presentations is least typical of herpesviral infection:

a. Encephalitis.
b. Ulcerative skin lesions.
c. Abortion.
d. Upper respiration disease.
e. Pancreatitis.

Back 56

e. Pancreatitis.

Herpesviruses induce: respiratory disease, abortion, lymphoproliferative changes, ulcerative skin lesions, and nervous system changes.

Front 57

One of the characteristics common to all herpesviruses is their ability to establish latency in their hosts. Choose the least true statement describing the effects of latency on diagnosis and control of herpesviral diseases:

a. Detection of latently infected animals is difficult, as these animals appear clinically normal and are not shedding the virus.
b. Latently infected animals can re-activate the virus when stressed. As such, they can develop herpesvirus-associated disease even if not exposed to a source of an infectious virus (e.g. a clinically sick animal).
c. Latently infected animals can be detected by serological testing, as they are always positive for anti-herpesviral antibody, even though they are not shedding the virus.
d. Latently infected animals are not infectious. However, they do become infectious when they re-activate the virus.
e. Vaccination against herpesviruses is typically ineffective in preventing development of latency.

Back 57

c. Latently infected animals can be detected by serological testing, as they are always positive for anti-herpesviral antibody, even though they are not shedding the virus.

Serological testing will not detect a latent virus

Front 58

You are presented with a young parrot that has recently lost some of its feathers. The owner also noticed that the bird's beak looks overgrown and shiny. Infection with what virus is most consistent with the above clinical signs?

a. Psitaccine parvovirus.
b. Avian papillomavirus.
c. Psitaccine beak and feather disease virus.
d. Avian adenovirus type 1.
e. Gallid herpesvirus type 2.

Back 58

c. Psitaccine beak and feather disease virus.

Both clinical signs are seen in psitaccine beak and feather disease virus.

Front 59

A serum sample from a mare that aborted due to a suspected Equid herpesvirus 1 infection tested positive for EHV-1 antibodies in a virus neutralisation test. Choose the incorrect interpretation of this result:

a) The positive result confirms that the mare aborted due to EHV-1 infection.
b) The mare might have aborted due to the EHV-1 infection, but in order to confirm a recent EHV-1 infection a four-fold rise in titre between the acute and convalescent serum samples would have to be demonstrated.
c) The positive result indicates that the mare has been likely exposed to EHV-1 at some point in the past, but tells us little about the timing of infection.
d) It is possible that the mare has never been infected with EHV-1, as the positive serum titre to EHV-1 may have resulted from either vaccination or infection with an antigenically similar virus EHV-4.
e) The mare has been exposed to either EHV-1 or EHV-4 at some point in the past.These two viruses cannot be distinguished serologically

Back 59

a) The positive result confirms that the mare aborted due to EHV-1 infection.

The presence of antibodies only suggests that the animal was exposed to the virus (or a vaccine) previously and does not indicate that exposure occurred recently (unless you take two samples and there is a four-fold increase in antibody titre).

Front 60

Which of the following is least true of Malignant catarrhal fever in New Zealand?

a. It occurs sporadically.
b. It is caused by Alcelaphine herpesvirus type 1.
c. It features a characteristic vasculitis.
d. It is most important in farmed red deer.
e. It is epidemiologically linked to contact with sheep.

Back 60

b. It is caused by Alcelaphine herpesvirus type 1.

Alcephaline herpesviruses are associated with Wildebeest in Africa and can result in epidemics of cattle. Ovine herpesvirus 2 causes MCF in New Zealand.

Front 61

Which of the following disease manifestations is least typical of herpesvirus infections in mammals?

a. Respiratory disease.
b. Hepatitis.
c. Central nervous system changes.
d. Lymphoproliferative disorders.
e. Ulcerative skin lesions.

Back 61

b. Hepatitis.

Herpesviruses induce: respiratory disease, abortion, lymphoproliferative changes, ulcerative skin lesions, and nervous system changes.

Front 62

Which of the following statements are true of alphaherpesviral latency? Choose all correct answers (there may be more than one).

a) During latency, virus particles cannot be detected during any routine diagnostic test.
b) Because of latency, measurement of antiviral antibodies is uninformative.
c) There may be no viral protein whatsoever in the host's body during latency.
d) During latency, virus can nevertheless be transmitted from host to host.
e) Latency is most often achieved in nerve ganglia and lymphocytes.

Back 62

a, b, c, e

D might be true? B might be untrue. Not too sure.

Front 63

Which of the following is not a well recognised consequence of equid herpesvirus 1 infection?

a. Abortion.
b. Encephalomyelitis.
c. Upper respiratory disease.
d. Genital mucosal ulcerations.
e. Perinatal foal mortality.

Back 63

d. Genital mucosal ulcerations.

All other choices are true, genital mucosal ulcerations are a consequence of Equid herpesvirus 3.

Front 64

Following EHV-1 infection, horses develop a life-long immunity to re-infection, but the latent virus can still be re-activated.

Back 64

F
Re-infection won't occur since the virus will continue to remain in the horse in its latent form.
Note that latency is a state of persistent infection.

Front 65

Vaccination against EHV-1 is protective against the neurological form of disease.

Back 65

F
EHV-1 vaccination provides no protection from neurologic disease.

Front 66

Herpesviruses stimulate solid (possibly life-long) immunity. Recovered animals are refractory to subsequent herpesviral infections.

Back 66

F
Herpesvirus will remain in the host in its latent form.

Front 67

Infection with the Aujeszky's disease virus causes fatal meningoencephalitis in cattle, sheep, dogs, foxes, and rabbits.

Back 67

T
This is a symptom of suid herpesvirus 1 when it infects these species, in adult pigs the infection is usually subclinical.

Front 68

Herpesviruses typically cause a short illness followed by recovery and elimination of the virus.

Back 68

F
Herpesvirus will remain in the host in its latent form.

Front 69

Which of the following statements is least true of adenoviruses in general?

a. They are non-enveloped and resistant in the environment.
b. Infection is associated with intracytoplasmic inclusion body formation.
c. Some can haemagglutinate mammalian red blood cells.
d. They can cause severe disease in dogs and some bird species.
e. They are being used in gene therapy and recombinant vaccine development.

Back 69

b. Infection is associated with intracytoplasmic inclusion body formation.

Adenoviruses produce intranuclear inclusion bodies.

Front 70

Canine adenovirus type 1 (CAV-1) can be excreted in urine of recovered dogs for a prolonged period of time.

Back 70

T
CAV-1 can be shed in faeces, saliva, and urine for up to 6 months after infection.

Front 71

Internal haemorrhages are typical of severe disease following infection with the Canine adenovirus type 1 (CAV-1) infection.

Back 71

T
Severe CAV-1 can cause haemorrhagic swollen liver.

Front 72

You are called to examine several young cattle with severe papillomatosis. The farmer would like to know whether or not he can use a vaccine to prevent warts in his cattle. Choose the best answer.

a) There are several commercially available multivalent vaccines against bovine papillomaviruses - all show similar efficacy.
b) There are several commercially available vaccines against bovine papillomatosis, but autogenous vaccine prepared from formalin-treated papilloma tissues has been proven to be the most efficacious.
c) There are several commercially available vaccines against bovine papillomatosis, but autogenous vaccine prepared from in-vitro cultured papillomavirus isolated from cases on the farm would be the most efficacious.

e) Bovine papillomatosis is typically a self-limiting disease. Efficacy of any vaccination has been difficult to prove. There are no commercially available vaccines against Bovine papillomaviruses.

Back 72

e) Bovine papillomatosis is typically a self-limiting disease. Efficacy of any vaccination has been difficult to prove. There are no commercially available vaccines against Bovine papillomaviruses.

Efficacy of vaccination is difficult to prove as papillomavirus infections resolve on their own.

Front 73

You are called to examine and provide advice about a group of young cattle, several of which have multiple cutaneous papillomas. Which of the following advisory comments is most accurate?

a) These papillomas are most likely to regress spontaneously over a period of months.
b) Cutaneous ones like this sometimes progress to malignancy.
c) We should make an autogenous vaccine to hasten regression of these papillomas.
d) We should vaccinate these cattle against Bovine papillomavirus type 4.
e) We should attempt virus cultivation and be guided by the results of that diagnostic test.

Back 73

a) These papillomas are most likely to regress spontaneously over a period of months.

Vaccine efficacy cannot be proven and malignancy is typically related to the ingestion of bracken fern

Front 74

One of your clients has several heifers affected by multiple warts. You explain that the likely cause of warts is a papillomavirus infection. The client has heard that it's possible to use an autogenous vaccine prepared from formalin-treated wart tissue to treat warts. He asks your opinion on the subject. Considering your knowledge of papillomaviruses, choose the best answer:

a) Papillomaviruses usually persist for long periods of time and are unlikely to regress without any treatment. It is therefore a good suggestion to try the autogenous vaccine.
b) There is only one antigenic type of bovine papillomavirus. As such, you advise your client that it would be cheaper to use a vaccine that has been recently prepared and successfully used by another client of yours.

d) Papillomavirus warts usually regress spontaneously and so it is difficult to assess the effectiveness of a vaccine.

Back 74

d) Papillomavirus warts usually regress spontaneously and so it is difficult to assess the effectiveness of a vaccine.

Efficacy of vaccination is difficult to prove as papillomavirus infections resolve on their own.

Front 75

Typically, papillomavirus infections in cattle cause development of warts, which disappear spontaneously after 4 to 6 months.

Back 75

T
Papillomaviruses generally resolve on their own so vaccination efficacy is hard to prove.

Front 76

Equine sarcoids have been shown to contain Bovine papillomavirus sequences.

Back 76

T
This is true, but experimental infection of bovine papillomavirus into horses results in sarcoid like lesions which regress.

Front 77

You are presented with a 9-week-old German shepherd puppy "Lucky". Lucky was vaccinated at the age of 6 weeks with a multivalent vaccine containing an attenuated strain of canine parvovirus, and is due for his second shot. However, yesterday Lucky seemed less playful, and has since lost his appetite and developed pasty pale faeces. ON examination, Lucky seemed quiet, but responsive, his temperature was 39.2 C, with slightly elevated heart rate and respiratory rate. You've performed a parvo "snap" test on a fecal sample from Lucky, which gave a strong positive result. Choose the most likely interpretation of the test result and the best course of action.

Back 77

The puppy is most likely in the very early stages of parvovirus infection. The best option would be to keep it in the hospital on IV fluids overnight and re-address the treatment plan the following morning, depending on the progression of clinical signs.

Vaccination only causes false positives for up to 2 weeks.

Front 78

Which of the following statements about Porcine parvovirus (PPV) is least correct?

a. PPV is highly resistant in the environment.
b. PPV is a major cause of reproductive failure in pigs.
c. Mummification of foetuses is a common feature of infection with PPV.
d. Abortions due to PPV are usually accompanied by enteritis and upper respiratory disease in pregnant sows.
e. PPV infection induces strong, possibly life-long immunity to re-infection.

Back 78

d. Abortions due to PPV are usually accompanied by enteritis and upper respiratory disease in pregnant sows

Porcine parvovirus produces no overt disease in mature pigs, only reproductive failure (SMEDI).

Front 79

You are working as a small animal veterinarian and have seen several cases of canine parvovirus disease over the past two months. You are concerned about the efficacy of your puppy vaccination schedule and decide to test sera from several of your client's dogs for antibodies against Canine parovirus type 2 (CPV-2). The following results come back from the laboratory:
CPV-2 haemagglutination inhibition (HI) titres:
Dog 1 = 160
Dog 2 = 5120
Dog 3 = 320
Dog 4 = 320
Dog 5 = 40

a) All dogs can be considered protected against infection with CPV-2 as all dogs have anti-CPV-2 antibodies.
b) The HI titre of Dog 5 is low and this dog may not be protected well against canine parvovirus disease. You recommend that Dog 5 is re-vaccinated against CPV-2.
c) The HI titre of Dog 2 is considerably higher than the HI titres of other dogs, which suggests that this dog might have been infected with CPV-2 in the past.

Back 79

a) All dogs can be considered protected against infection with CPV-2 as all dogs have anti-CPV-2 antibodies.

The amount of antibody found will vary among individuals but will multiply considerably if infection occurs.

Front 80

Parvoviruses:

a. Can be easily a. killed by all common disinfectants.
b. Can survive extremely well outside their hosts and remain infectious for weeks to months.
c. Cause more severe disease in older animals, as the majority of young animals are protected by maternally-derived antibodies.
d. Do not induce strong immune responses.
e. Show little cross-protection between a variety of existing serotypes.

Back 80

b. Can survive extremely well outside their hosts and remain infectious for weeks to months.

Parvoviruses maintain themselves in a population through their resistive properties, compare this to herpesviruses which maintain themselves in individuals through latency.

Front 81

One of your clients has adopted a stray female cat, which turned out to be pregnant. The client wants to know whether or not her newly adopted cat should be vaccinated against Feline panleucopenia. Choose the best answer:

a) Feline panleucopenia virus is a fragile virus, so the cat is unlikely to come across it in the outside environment. As such, it would be best to wait to vaccinate the queen until after she had her kittens.
b) It would be best to vaccinate the queen with a live attenuated vaccine, as such vaccines provide a better protection following a single vaccination in comparison with killed vaccines.
c) It would be best to vaccinate the queen with a killed vaccine, as such vaccines do not have a potential of crossing the placenta and causing foetal death or abnormalities.
d) It would be best to vaccinate the queen with a live attenuated vaccine, as long as the queen is not in her last two weeks of pregnancy to avoid the possibility of cerebellar hypoplasia in newborn kittens

Back 81

c) It would be best to vaccinate the queen with a killed vaccine, as such vaccines do not have a potential of crossing the placenta and causing foetal death or abnormalities.

A formalin-inactivated (killed) virus is used to vaccinate pregnant queens and young kittens at risk of feline panleucopenia virus.

Front 82

What would you expect to be the most likely reason for a false negative result when using in-practice diagnostic test kits for the detection of canine parvovirus antigen in faeces?

a. The test is done too early, virus is not yet present in the faeces.
b. The test is done too early, viral antigen has not matured.
c. The test is done too late, virus is no longer present.
d. The test is done too late, non-specific blocking substances are present.
e. The test is done too late, specific antiviral antibodies block viral epitopes.

Back 82

e. The test is done too late, specific antiviral antibodies block viral epitopes.

The diagnostic test requires unblocked antigen (the epitope) to be present but antibodies from the animal's immune system will act to block these and may block all antigens over time.

Front 83

What is the most important advantage of a "high titre, low passage" vaccine against CPV-2, as compared with a more conventional modified live vaccine?

a) High titre, low passage vaccines are safer than more conventional.
b) High titre, low passage vacines are less expensive than more conventional modified live vaccines (because of the low passage number).
c) Because of its potency and safety, the vaccine can be used therapeutically for treatment of parvovirus-infected puppies.
d) Puppy vaccinations need to be given less frequently than when using a more conventional modified live vaccine.
e) High titre, low passage vaccines 'break through' maternally transferred passive immunity earlier than do more conventional vaccines.

Back 83

e) High titre, low passage vaccines 'break through' maternally transferred passive immunity earlier than do more conventional vaccines.

This feature allows for these types of vaccines to reliably protect puppies at 12 weeks of age. Also note that the more titres a parvovirus goes through the more its virulence is reduced.

Front 84

From the list below, select the least useful test for the diagnosis of canine parvoviral enteritis:

a. Vaccination history and physical examination.
b. Direct and light microscopic inspection of the faeces.
c. Faecal parvoviral antigen detection.
d. Light microscopic examination of a peripheral blood smear.
e. Haemagglutination test on faeces.

Back 84

b. Direct and light microscopic inspection of the faeces.

The virus won't be visible using a conventional microscope but intranuclear inclusion bodies may be visible in a blood smear.

Front 85

The most likely reason why we so infrequently observe canine parvovirus type 2 (CPV-2)-associated myocarditis in very young puppies is that:

a) CPV-2 has evolved within its new host and no longer tends to cause this severe effect; it is "settling down" in its new host.
b) Modern vaccines are able to break through maternal immunity and induce active immunity in vaccinated puppies early enough to prevent myocarditis.
c) Panleucopenia has replaced myocarditis as the most likely consequence of infection in very young puppies.
d) Much of the adult canine population is now immune: maternally transferred passive immunity protects puppies at the critical, early life stage.
e) CPV-2-associated myocarditis is actually very difficult to confirm: we are probably failing to observe it, although it remains present at a lower level.

Back 85

d) Much of the adult canine population is now immune: maternally transferred passive immunity protects puppies at the critical, early life stage.

all other choices are false

Front 86

High titre, low passage vaccines have been developed to protect against CPV-2. From the list below, choose the most precise description of the meaning of "high titre, low passage" in this specific context.

a) The vaccine provokes the production of high titre antibodies because it is very similar to the natural version of the virus.
b) The vaccine provokes the production of high tire antibodies and is very safe because it is low passage.
c) The vaccine contains a large number of virus particles per millilitre (ml) and is very safe because of its low passage.
d) The vaccine contains a large number of virus particles per millilitre (ml) and is very similar to the natural version of the virus.
e) None of the above descriptions is sufficiently precise.

Back 86

e) None of the above descriptions is sufficiently precise.

Not sure, a high titre vaccine should result in low quantities of virus, also repeated dilution is shown to reduce virulence in parvoviruses.

Front 87

An outbreak of porcine Post-weaning Multisystemic Wasting Syndrome (PMWS) has recently been detected in the North Island of New Zealand. Which of the following statements about PMWS and Porcine circovirus type 2 (PCV-2) is least accurate, given our current understanding of the disease?

a) PCV-2 is necessary, but probably not sufficient to cause the disease.
b) PCV-2 was known to be present in New Zealand before cases of PMWS were recently observed.
c) Immune stimulation (by vaccination or other infections) may increase the probability of observing PMWS in PCV-2 infected pigs.
d) Replication of PCV-2 requires actively dividing cells, this may explain the need for immunostimulation.
e) Certain genetic strains of PCV-2 are known to be more likely to cause PMWS.

Back 87

e) Certain genetic strains of PCV-2 are known to be more likely to cause PMWS.

All other choices are true

Front 88

Which of the following is not a feature of circoviruses?

a. Tiny DNA viruses.
b. Single stranded genome.
c. Closed circular genome (like a plasmid).
d. Very resistant in the environment.
e. Rapidly cleared from the body after infection resolves.

Back 88

e. Rapidly cleared from the body after infection resolves.

All other choices are true

Front 89

Which of the following diseases/disorders can be caused by a circovirus? Choose all correct answers (there may be more than one).

a. Psittacine beak and feather disease in young birds.
b. Pheasant marble spleen disease in older birds.
c. Haemorrhagic enteritis in young turkeys.
d. Anaemia in 2-3 week old chicks.
e. Hepatitis in adult chicks.

Back 89

a. Psittacine beak and feather disease in young birds.
d. Anaemia in 2-3 week old chicks.

B, C, and E are caused by adenoviruses.

Front 90

The results of a parvovirus haemagglutination inhibition (HI) test done on the sera of three six week old puppies are as follows: Puppy A 1:20, puppy B 1:540, and puppy C 1:160. If you were to vaccinate all three puppies with a single dose of a vaccine containing attenuated live canine parvovirus, which of the puppies would be most likely to develop immune response to the vaccine that would be protective against subsequent challenge with virulent parvovirus?

a) Puppy A. It has the highest level of antibody and vaccination will boost the already high level of immunity.
b) Puppy A. It has the lowest levels of maternal antibody and as such it is most likely to respond to vaccination by mounting an active immune response.
c) Puppy B. It has the highest level of antibody and vaccination will boost the already high level of immunity.
d) Puppy B. It has the lowest level of antibody and as such it is most likely to respond to vaccination by mounting an active immune response.

Back 90

b) Puppy A. It has the lowest levels of maternal antibody and as such it is most likely to respond to vaccination by mounting an active immune response.

Higher levels of maternal antibodies would interfere with a live virus vaccine.

Front 91

Immunity to Canine parvovirus disease following natural infection is most likely life-long.

Back 91

T
Parvovirus recovery results in solid immunity.

Front 92

Myocarditis associated with Canine parvovirus type 2 (CPV-2) infection is rarely seen now, because most puppies have some level of maternal immunity to CPV-2 during the first few weeks of life.

Back 92

T
The majority of the adult canine population is now immune to the virus, this immunity is passed down via maternal antibodies.

Front 93

Canine parvovirus infection is extremely unlikely to be a cause of gastroenteritis in a 12 week-old puppy that had been vaccinated twice against parvovirus at 6 and 9 weeks of age.

Back 93

F
Canine parvovirus vaccines only provide reliably protection past 12 weeks of age.

Front 94

Internal haemorrhages are typical of severe disease following infection with Canine parvovirus type 1 (CPV-1) infection.

Back 94

F
CPV-1 is avirulent.

Front 95

The levels of maternally derived antibodies against canine parvovirus are similar in all puppies from the same litter.

Back 95

F
Antibody levels differ between individual pups as some may acquire more antibody due to suckling more.

Front 96

Parvoviruses can remain infectious in faecal material for weeks to months.

Back 96

T
Parvoviruses maintain themselves in a population through their resistive properties, compare this to herpesviruses which maintain themselves in individuals through latency.

Front 97

Which of the following statements about antigenic change in influenza A viruses is least true?
a. Antigenic drift is a relatively small change that does not change the H and N subtypes.
b. Antigenic shift occurs as a result of re-assortment of the 8 segments of the virus genome.
c. Antigenic drift occurs through mutations in the genes encoding surface glycoproteins.
d. Antigenic drift leads to a rapid change in a subtype.
e. Antigenic shift may arise as a result of numerous small “drift-like” changes.

Back 97

d. Antigenic drift leads to a rapid change in a subtype.

All other choices are true. Antigenic drift is a process of gradual change over time. The basic viral subtype remains unaffected. Note however that antigenic drift over time can lead to antigenic shift (a change in subtype).

Front 98

Which of the following statements regarding ecology of Influenza viruses is least true?
a. All different N and H subtypes of Influenza viruses circulate among wild waterfowl.
b. Influenza virus infections in wild waterfowl are usually asymptomatic.
c. Immunity following infection with a given H subtype of influenza virus is strong and long-lasting, but does not cross-protect against other H subtypes.
d. Pigs possess both “human” and “avian” types of receptors for influenza viruses.
e. Influenza viruses are can be isolated from cloacal swabs collected from infected birds.

Back 98

c. Immunity following infection with a given H subtype of influenza virus is strong and long-lasting, but does not cross-protect against other H subtypes.

All other choices are true. Influenza virus immunity is short lived, e.g. horses that recover from equine influenza can be re-infected within 12 months.

Front 99

People working on commercial pig farms are often required to be vaccinated against a seasonal human flu virus. The most important justification for this requirement is:
a. To minimize possibility of transmission of human influenza viruses to swine.
b. To minimize possibility of transmission of human influenza viruses between workers.
c. To protect people working with pigs against infection with the swine influenza virus.
d. To minimize possibility of recombination between human and animal influenza viruses in a human host.
e. To minimize environmental contamination of piggery with influenza viruses by reducing the level of influenza virus shedding by infected people.

Back 99

d. To minimize possibility of recombination between human and animal influenza viruses in a human host.

Pigs possess both "human" and "avian" types of influenza virus receptors, making recombination between human and avian strains of influenza virus possible which can potentially lead to a more virulent strain of human influenza (e.g. Spanish flu pandemic).

Front 100

During the recent outbreak of Equine influenza in Australia a recombinant Canarypox influenza vaccine was used to help contain the outbreak and eradicate Equine influenza from Australia. The main advantage of this type of vaccine over other available vaccines was:
a. It provides long-lasting immunity to Equine influenza.
b. It contains several serotypes of Equine influenza, so is more likely to be effective against a variety of field isolates.
c. It allows for serological differentiation between vaccinated and infected animals.
d. It is significantly cheaper than other available vaccines.
e. It does not require cold chain, as canary poxvirus is very stable in the environment.

Back 100

c. It allows for serological differentiation between vaccinated and infected animals.

Live recombinant canarypox vaccine allows the expression of haemagglutinin of the equine influenza virus. Since haemagglutinin is expressed but neuraminidase is not, vaccinated and infected animals can be serologically differentiated. (not actually sure about this one)

Front 101

Which of the following statements about antigenic change in influenza A
a. Antigenic drift is a relatively small change that does a. not change the H-N subtype.
b. Antigenic drift occurs as a result of reassortment of the 8 segments in the virus genome.
c. Antigenic drift arises mostly by sequential point mutations in key parts of the genes encoding the surface glycoprotein molecules.
d. Antigenic shift can lead to influenza pandemics.
e. Antigenic shift may arise as a result of numerous small “drift-like” changes.

Back 101

b. Antigenic drift occurs as a result of reassortment of the 8 segments in the virus genome.

All other choices are true. Antigenic drift is a process of gradual change over time which does not affect the basic viral subtype. Antigenic shift is a much more rapid change that occurs as a result of reassortment of the 8 segments of the virus genome

Front 102

Highly pathogenic avian influenza (HPAI) is very much in the news lately. In rich countries, farm and government workers handling large numbers of chicken carcasses during an HPAI outbreak (i.e., cullers) are encouraged to take an anti-influenza drug, such as oseltamivir. Yet some cullers and other workers choose not to do so. From the list below, and thinking from a national and international perspective, select the most important underlying reason why cullers should be required to take an anti-influenza drug while working with HPAI carcasses.
a. HPAI can directly infect and kill humans.
b. Cullers can spread HPAI to their family members.
c. Cullers may be incubating human influenza while working.
d. Cullers may encounter more than one strain of HPAI virus in one working day.
e. Cullers may come into contact with pigs shortly after working in the chicken house.

Back 102

c. Cullers may be incubating human influenza while working.

(not sure) A is true. B is false. D does not seem relevant. If E then refer to answer to Q3. C is most important because if a culler is incubating human influenza and then also becomes infected with HPAI recombination may occur leading to a strain of HPAI which can be transmitted from human to human.

Front 103

The term "highly pathogenic avian influenza virus" relates to:
a. The virulence of the virus to chickens.
b. The virulence of the virus to domestic ducks.
c. The virulence of the virus to wild waterfowl.
d. The general virulence of the virus, without any specific host in mind - the term indicates that the virus is able to cause disease in several species.
e. The virulence to people - the term indicates that the virus is able to cause disease in humans.

Back 103

a. The virulence of the virus to chickens.

Strains of avian influenza virus are categorised as having high (HPAI) or low pathogenicity (LPAI) based on the severity of disease and mortality caused in chickens.

Front 104

Influenza A viruses share all of the following features, except:
a. Segmented RNA genome.
b. Short incubation period.
c. Haemagglutinin and neuraminiadase surface proteins.
d. Spread predominantly by respiratory aerosols in birds and mammals.
e. Fragile in the environment.

Back 104

d. Spread predominantly by respiratory aerosols in birds and mammals.

All other choices are true. For human, swine, and equine influenza initial infection occurs due to aerosol exposure of the respiratory tract. In birds, initial infection is mainly by ingestion of contaminated feed or water (this is because the virus replicates well in the intestinal

Front 105

Which of the following statements about influenza A viruses is least true?
a. There is a large diversity of avian Influenza viruses.
b. Both avian and mammalian Influenza A viruses typically have a short incubation period.
c. Haemagglutinin and neuraminidase surface proteins are important targets for host immune responses against Influenza A viruses.
d. Both avian and mammlian Influenza A viruses spread predominantly by respiratory aerosols.
e. Both avian and mammalian Influenza A viruses are fragile in the environment.

Back 105

d. Both avian and mammlian Influenza A viruses spread predominantly by respiratory aerosols.

All other choices are true. Refer to answer for Q8 for more info. Also note that aerosol exposure can be important, particularly once infection has been introduced into a flock but initial infection is predominantly via ingestion of contaminated feed or water.

Front 106

Influenza A viruses share all of the following features, except:
a. Single stranded RNA genome in 8 segments.
b. Fragile in the environment.
c. Haemagglutinin and neuraminidase surface glycoproteins.
d. Spread mostly by aerosols in birds and mammals.
e. Sensitive to heat, drying, detergents and disinfectants.

Back 106

d. Spread mostly by aerosols in birds and mammals.

All other choices are true. For human, swine, and equine influenza initial infection occurs due to aerosol exposure of the respiratory tract. In birds, initial infection is mainly by ingestion of contaminated feed or water (this is because the virus replicates well in the intestinal epithelium of birds).

Front 107

What strain of influenza A virus caused enormous concern in Southeast Asia around 2007?
a. H1N1.
b. H7N7.
c. H5N1.
d. H5N3.
e. H3N8.

Back 107

c. H5N1.

H5N1 is commonly known as "avian influenza" or "bird flu" and is enzootic in Southeast Asia.

Front 108

Avian influenza viruses replicate predominantly in the gastrointestinal track of infected birds and are spread via faecal-oral route.

Back 108

True
In birds, initial influenza infection is mainly by ingestion of contaminated feed or water (this is because the virus replicates well in the intestinal epithelium of birds). Also note that aerosol exposure can be important, particularly once infection has been introduced into a flock but initial infection is predominantly via ingestion of contaminated feed or water.

Front 109

Pigs possess both human and avian types of receptors for influenza viruses.

Back 109

True
Pigs possess both alpha 2-3 receptor binding sites found in birds and alpha 2-6 receptors found in humans. This allows pigs to serve as an intermediate host which can result in the formation of novel viruses.

Front 110

Equine influenza is a common cause of equine respiratory disease in New Zealand.

Back 110

False
Equine influenza is an important cause of equine respiratory disease but the virus is not present in New Zealand and is therefore notifiable.

Front 111

Haemagglutinin of the influenza viruses is one of the determinants for viral virulence.

Back 111

True
Haemagglutinin is an important determinant of virus host range and virulence while neuraminidase palys a role in virus release from an infected cell and the spread of the virus between cells.

Front 112

Velogenic Newcastle disease and highly pathogenic avian influenza are clinically indistinguishable.

Back 112

True
The explosive nature of disease outbreak for both of these diseases means that velogenic Newcastle disease would be on the same list of differential diagnoses as HPAI (Study Guide 16-8).

Front 113

Which of the following statements about Rinderpest is least true?
a. There is only one viral serotype.
b. The virus is rapidly inactivated outside the host.
c. An effective attenuated live virus vaccine produces life-long immunity.
d. A robust “cold chain” is essential to eradication efforts.
e. Global eradication is very unlikely to be successful.

Back 113

e) Global eradication is very unlikely to be successful.

All other choices are true. GREP, the Global Rinderpest Eradication Programme has been active since 1994.

Front 114

Which of the following characteristics of morbilliviruses is least true?
a. Morbilliviruses are very contagious.
b. They are fragile and easily killed outside their hosts.
c. They target epithelial, neural and lymphoid tissues.
d. They induce strong, but short-lasting immune responses.
e. Vaccination has been shown to be very effective in controlling morbillivirus infections.

Back 114

d. They induce strong, but short-lasting immune responses.

All other choices are true. A fundamental characteristic of morbilliviruses is that they induce life-long immunity in survivors of infection.

Front 115

Which of the following is the most significant point of similarity between canine distemper virus and Rinderpest virus?
a. There is only one serotype for each of these virus species.
b. Neurological disease is a consistent feature of clinical picture for infection with both of these viruses.
c. Both viruses are difficult to disinfect and survive well in the environment.
d. Vaccination against these viruses produces strong, but short-lived immunity.
e. Infection with either virus causes severe clinical signs in all infected animals.

Back 115

a. There is only one serotype for each of these virus species.

All other choices are false. Both canine distemper virus and Rinderpest only have one serotype.

Front 116

Which of the following feature is least applicable to Paramyxovirdidae?
a. Good vaccines exist for several of the viruses in this family.
b. They are fragile in the environment and don’t survive well outside their hosts.
c. Some have zoonotic potential.
d. They can undergo rapid genetic change through the exchange of the genomic segments.
e. Some have a wildlife reservoir.

Back 116

d. They can undergo rapid genetic change through the exchange of the genomic segments.

All other choices are true. D is definitely false, it would be more an appropriate description of antigenic shift in Orthomyxoviridae.

Front 117

Which of the following statements about Bovine parainfluenza type 3 (BPiV-3) virus is least true?
a. Bovine PI-3 virus infection provokes a strong, long-lasting immune response in both sheep and cattle.
b. Uncomplicated infection with the Bovine PI-3 virus tends to cause mild or subclinical disease.
c. Infection with the Bovine PI-3 virus is associated with shipping fever.
d. Infection with the Bovine PI-3 virus may predispose to secondary bacterial infections.
e. Causative association between disease and the Bovine PI-3 virus infection is difficult to demonstrate, as the virus is ubiquitous and has been isolated from both diseased and healthy animals.

Back 117

a. Bovine PI-3 virus infection provokes a strong, long-lasting immune response in both sheep and cattle.

BPiV-3 provokes a strong but short-lasting immune response. This means that reinfection can occur readily.

Front 118

An inquisitive client who breeds dogs asks your advice upon the wisdom (or otherwise) of vaccinating 6 week-old puppies against canine distemper using a measles virus vaccine. Which of the following pieces of advice is least valuable?
a. Measles virus vaccines can be used to protect very young puppies because there is extensive induced cross protection between measles virus and canine distemper virus.
b. Maternally transferred passive immunity sufficient to neutralise an attenuated canine distemper virus vaccine will not neutralise an attenuated measles virus vaccine.
c. This approach will work best if the bitch (dam) was herself vaccinated with a measles vaccine after she was 12 weeks of age.
d. This approach is not used very often, since canine distemper has become quite rare and modern distemper vaccines are safe to use in young puppies.
e. In the face of a distemper outbreak, or in other situations where young puppies may be exposed to distemper virus, this approach may have merit.

Back 118

c. This approach will work best if the bitch (dam) was herself vaccinated with a measles vaccine after she was 12 weeks of age.

All other choices are true. C is false, the approach being described will not work if the bitch was vaccinated with measles vaccine after 12 weeks of age.

Front 119

The velogenic form of Newcastle disease in poultry:
a. Typically produces very characteristic clinical signs. As such, laboratory diagnosis is rarely required.
b. Causes clinical signs that are indistinguishable from clinical signs of pathogenic avian influenza infection. As such, diagnosis has to be confirmed through laboratory testing.
c. Typically causes mild or subclinical disease in domestic poultry and therefore is of little significance. Laboratory testing is rarely requested.
d. Can cause severe disease with high mortality in non-immune domestic poultry. However, the virus is endemic in New Zealand and controlled well by vaccination.
e. Causes subclinical disease in domestic poultry, but severe disease with high mortality in ducks. It can be differentiated from the highly pathogenic form of avian influenza based on this clinical feature

Back 119

b. Causes clinical signs that are indistinguishable from clinical signs of pathogenic avian influenza infection. As such, diagnosis has to be confirmed through laboratory testing.

The explosive nature of disease outbreak for both of these diseases means that velogenic Newcastle disease would be on the same list of differential diagnoses as HPAI

Front 120

Paramyxovirus infected cells may show which of the following useful diagnostic features:
a. Cytoplasmic inclusion bodies.
b. Multinucleated giant cells.
c. Haemadsorption.
d. All of the above.
e. None of the above.

Back 120

d. All of the above.

All are true. Paramyxoviruses form acidophilic inclusion bodies in the cytoplasm, some (e.g. morbilliviruses) also form inclusion bodies in the nucleus. Glycoprotein F, a glycoprotein spike found on the envelope of paramyxoviruses, mediates cell to cell fusion resulting in syncytia (multinucleated giant cells). Parainfluenza viruses can be identified by haemadsorption

Front 121

The picture below shows a cow with ulcerative lesions in its mouth. Which of the following viruses are least likely to have caused these lesions?
a. Bovine viral diarrhoea virus.
b. Foot-and-mouth disease virus.
c. Bovine parainfluenza type 3 virus.
d. Vesicular stomatitis virus.
e. Rinderspest virus.

Back 121

c. Bovine parainfluenza type 3 virus.

All other choices can cause oral lesions, BPiV-3 is a minor upper respiratory pathogen associated with shipping fever or calf pneumonia. The image shows oral lesions caused by Rinderpest and Foot-and-Mouth Disease.

Front 122

Which of the following features is least applicable to members of Paramyxoviridae?
a. They are enveloped and fragile in the environment.
b. Their genome is all in one piece (non-segmented).
c. They replicate in the cell nucleus.
d. Members of a particular virus species are antigenically similar throughout the world.
e. Members of a particular virus species remain antigenically stable over prolonged periods of time.

Back 122

c. They replicate in the cell nucleus.

All other choices are true. A characteristic feature of Paramyxoviruses is that they replicate within the cytoplasm.

Front 123

Which of the following statements about Hendravirus is untrue?
a. It was first recognised in Queensland, Australia as a cause of disease in horses and human beings.
b. It can cause neurological disease in both humans and horses.
c. It is unusually hardy (resistant) in the environment for a paramyxovirus.
d. Various species of fruit bats serve as 'asymptomatic' reservoir hosts.
e. Infection occurs sporadically in horses, presumably as a consequence of eating fruit bat droppings or urine.

Back 123

c. It is unusually hardy (resistant) in the environment for a paramyxovirus.

Hendravirus is very fragile and can be easily killed by heat, desiccation, or disinfection.

Front 124

Which of the following statements about Nipahvirus (Nipavirus) is least true?
a. It was first recognised in Malaysia as a cause of disease in humans and pigs.
b. Its closest relative among the paramyxoviruses is Turkey rhinotracheitis virus.
c. Pigs, humans, dogs, cats, rats and horses can be infected.
d. There is serological evidence that fruit bats may be a reservoir host.
e. Control was initially achieved by minimising contact between infected pigs and people.

Back 124

b. Its closest relative among the paramyxoviruses is Turkey rhinotracheitis virus.

All other choices are true. Nipahvirus is most closely related to Hendravirus as both are in the same genus. Turkey rhinotracheitis is found in a different subfamily.

Front 125

Which of the following statements about Newcastle disease virus and its pathotypes is most true?
a. The virus is very fragile in the environment.
b. Vaccination against the lentogenic (avirulent) pathotype will unfortunately not afford protection against the velogenic (highly virulent) pathotypes.
c. New Zealand only has lentogenic, avirulent strains of the virus.
d. The potential for mutation of lentogenic forms to create velogenic variants is a constant worry.
e. Mesogenic forms are neurotropic, velogenic forms are viscerotropic.

Back 125

c. New Zealand only has lentogenic, avirulent strains of the virus.

The velogenic form of Newcastle is notifiable in New Zealand.

Front 126

Morbilliviruses induce strong, long-lasting immunity in survivors of infection.

Back 126

True
This is a fundamental characteristic of morbilliviruses.

Front 127

Bovine parainfluenza type 3 (PI-3) is a common cause of abortions in cattle.

Back 127

False
BPiV-3 is commonly associated with shipping fever or calf pneumonia, it is a minor upper respiratory pathogen.

Front 128

The velogenic biotype of Newcastle disease virus is endemic in New Zealand.

Back 128

False
Velogenic Newcastle disease is not found in New Zealand and is considered a notifiable in NZ.

Front 129

Velogenic Newcastle disease and highly pathogenic avian influenza are clinically indistinguishable.

Back 129

True
The explosive nature of disease outbreak for both of these diseases means that velogenic Newcastle disease would be on the same list of differential diagnoses as HPAI

Front 130

Paramyxovirus infection may cause both intranuclear and intracytoplasmic inclusion bodies to form.

Back 130

True
All paramyxoviruses can cause intracytoplasmic inclusion bodies, morbilliviruses can also cause intranuclear inclusion bodies.

Front 131

Viruses in the Paramyxoviridae family characteristically cause syncytium formation in cell culture.

Back 131

True
Paramyxoviruses characteristically induce syncytium formation in cell cultures.

Front 132

Many members of the Paramyxoviridae family engender strong immune responses.

Back 132

True
Strong but short-lived immune responses occur with paramyxoviruses such as in Bovine Parainfluenza 3. Life-long immunity occurs with morbilliviruses.

Front 133

Viruses of the Paramyxoviridae family have two kinds of surface glycoprotein.

Back 133

True
Paramyxoviruses have one glycoprotein for attachment (HN, H, or G) and one glycoprotein for fusion (F).

Front 134

Some members of the Paramyxoviridae family are haemagglutinators.

Back 134

True
Parainfluenza viruses are haemagglutinators.

Front 135

Which statement related to Feline infectious peritonitis (FIP) is least true?
a. FIP is usually caused by a mutation in the genome of the feline enteric coronavirus.
b. Unlike enteric coronavirus, FIP has the tropism for macrophages.
c. Diagnosis of FIP can be confirmed based on virus isolation from faeces.
d. Feline leukaemia virus causes immunosuppression and is associated with increased frequency of FIP.
e. The incidence of clinical FIP in New Zealand is low.

Back 135

c. Diagnosis of FIP can be confirmed based on virus isolation from faeces.

FIP would not be isolated from faeces since it targets macrophages. Diagnosis by virus isolation in macrophages is possible, but the disease is usually diagnosed by a combination of findings.

Front 136

Which of the following viruses is least likely to cause abortion or congenital defects in cattle:
a. Bovine viral diarrhoea.
b. Akabane disease virus.
c. Bovine coronavirus.
d. Bluetongue virus.
e. Rift valley fever virus.

Back 136

c. Bovine coronavirus.

All other diseases listed are capable of causing abortions in cattle. Also, bovine coronavirus generally causes mild symptoms in adult cattle, severe disease only occurs in young calves which would be too young to be pregnant.

Front 137

Which of the following statements about coronaviruses is correct?
a. Coronaviruses typically cause mild respiratory or gastrointestinal infections in several species.
b. Coronaviruses survive well in the environment.
c. Coronaviruses are commonly associated with malignancy in cats.
d. Coronaviruses have the smallest genomes of the known RNA viruses.
e. Coronaviruses are not known to pose a zoonotic risk.

Back 137

a. Coronaviruses typically cause mild respiratory or gastrointestinal infections in several species.

All other choices are false. Coronaviruses tend to cause mild disease in adults but can cause more severe infections in younger animals.

Front 138

Which of the following best describes similarity between coronaviral diarrhoea and rotaviral diarrhoea in young calves?
a. Both are caused by unusually hardy viruses that cause massive environmental contamination.
b. In both cases there is strong zoonotic potential.
c. Long-term persistence of the causative virus in vivo is important in the epizootiology of both diseases.
d. In both cases mature villous cells, rather than crypt cells, are targeted.
e. Both viruses are not very host-specific and one serotype can infect multiple animal species.

Back 138

d. In both cases mature villous cells, rather than crypt cells, are targeted.

D is true and most specific. All other choices are false (B could be considered true since both diseases are technically zoonotic, but zoonotic spread of rotaviruses is unusual).

Front 139

From the point of view of viral pathogenesis, there are some interesting parallels between mucosal disease of cattle and feline infectious peritonitis. From the list below, select the most accurately stated point of similarity.
a. In both cases, a low pathogenicity 'precursor' virus persists in the host and later mutates to become highly pathogenic.
b. In both cases, horizontal transmission of the mutant, highly pathogenic variant virus is a very rare event.
c. In both cases, mutation is known to change the cellular tropism of the 'precursor' virus so that the mutant variant has a markedly different and well characterised cell tropism.
d. In both cases, horizontal transmission of the relatively low virulence 'precursor' virus is a very rare event.
e. In both cases, the host is fully immunotolerant of the low virulence 'precursor' virus.

Back 139

a. In both cases, a low pathogenicity 'precursor' virus persists in the host and later mutates to become highly pathogenic.

All other choices are false. The precursor to FIP is feline enteric coronavirus and the precursor to Mucosal Disease is Bovine Viral Diarrhoea (BVD).

Front 140

You are called to help with an outbreak of diarrhoea in a mob of 1-weekold calves. The calves are depressed, dehydrated and show watery yellow diarrhoea. Older animals seem unaffected. The majority of calves recover in about 4-5 days, but there are some mortalities. Which viral agents are most likely to be involved in this outbreak?
a. Bovine coronavirus.
b. Bovine rotavirus.
c. Bovine viral diarrhoea virus.
d. a or b.
e. a, b, or c.

Back 140

d. a or b.

Bovine coronavirus and bovine rotavirus are clinically indistinguishable, both diseases show the symptoms described in the question. Bovine viral diarrhoea can be ruled out since BVD is common in animals 6-18 months of age (after passive maternal immunity is gone). Calves may be born with persistent BVD infection but tend to be clinically normal (may have diarrhoea, but it won't be yellow).

Front 141

You are asked to comment on whether or not your client's adult cat should be vaccinated against Feline infectious peritonitis (FIP). Choose the least correct statement from the options below.
a. There is no vaccine available in New Zealand, although there is a vaccine available overseas.
b. The available vaccine has shown good level of protection against FIP in adult immunocompetent cats.
c. FIP usually occurs as a result of mutation of feline enteric coronavirus, and vaccination will have no effects on that process.
d. The best way to minimize the risk of FIP is to minimize the chance of infection with feline coronavirus early in the cat's life, although this is difficult to achieve.
e. The available vaccine does not evoke systemic immune responses, as these can facilitate development of disease.

Back 141

c. FIP usually occurs as a result of mutation of feline enteric coronavirus, and vaccination will have no effects on that process.

C is most true. There is a vaccine available overseas, however its effectiveness is questionable since FIP occurs due to a de novo mutation of FEC which is common in most cats (therefore hard to avoid).

Front 142

Which of the following statements about coronaviruses is correct?
a. Coronaviruses typically cause mild respiratory or gastrointestinal infections in several species.
b. Coronaviruses survive well in the environment.
c. Coronaviruses are commonly associated with malignancy in cats.
d. Coronaviruses have the smallest genomes of the known RNA viruses.
e. Coronaviruses are not known to pose a zoonotic risk.

Back 142

a. Coronaviruses typically cause mild respiratory or gastrointestinal infections in several species.

All other choices are false.

Front 143

Feline infectious peritonitis (FIP) and Feline enteric coronavirus (FEC) are two antigenically distinct coronaviruses of cats.

Back 143

False
FEC and FIP are serologically indistinguishable. FIP is thought to be a more virulent mutation of FEC which occurs in vivo.

Front 144

Bovine coronavirus can cause diarrhoea in people.

Back 144

True
Bovine coronavirus is zoonotic and can lead to diarrhoea in people.

Front 145

Most coronaviruses cause mild disease in adults, but more severe disease in newborn animals.

Back 145

True
Most coronaviruses cause mild disease, however disease is more severe in newborn animals which lack strong immune systems. There are exceptions, some coronaviruses which cause severe disease in adults include: feline infectious peritonitis (FIP) in cats, transmissible gastroenteritis (TGE) in pigs , severe acute respiratory syndrome (SARS) in humans.

Front 146

Feline infectious peritonitis, transmissible gastroenteritis and some cases of puppy diarrhoea are caused by coronaviruses.

Back 146

True
These are all diseases caused by coronaviruses.

Front 147

About 60% of human common colds are caused by coronaviruses.

Back 147

False
Human colds are caused by rhinovirus which is part of the picornaviridae family.

Front 148

Most coronaviruses cause mild disease in adults and more severe disease in newborn animals.

Back 148

True
Coronaviruses tend to cause mild disease symptoms in adult animals but disease can be more severe in young animals with weak immune systems.

Front 149

Mammalian coronaviruses have a tropism for ectodermal cells.

Back 149

False
Most coronaviruses replicate in cells of endodermal origin such as the liver, respiratory tract, or alimentary tract. Haemagglutinating encephalitis virus can be found in neural tissue (ectoderm). While feline infectious peritonitis can be found in macrophages (mesoderm, I think).

Front 150

Coronaviruses have the smallest genomes of the known RNA viruses.

Back 150

False
Coronaviruses are the largest RNA viruses, retroviruses are the smallest.

Front 151

Coronaviruses generally grow very well in cell culture, producing a strong cytopathic effect.

Back 151

False
Coronaviruses produce little, if any, cytopathic effects. They generally do not grow well in culture.

Front 152

Coronaviruses are moderately fragile in the environment, surviving 1-2 days at room temperature.

Back 152

True
Coronaviruses are moderately fragile, they can be destroyed by lipid solvents or extremes of pH but will survive for 1-2 days if left alone at room temperature.

Front 153

The 'naked' RNA of a coronavirus is infectious.

Back 153

True
Coronaviruses are a positive sense RNA virus so they are readable as mRNA.

Front 154

Coronaviruses mutate and evolve relatively slowly compared with most other RNA viruses.

Back 154

False
Coronaviruses mutate quickly enough for in vivo mutations to occur within animals such as
with feline enteric coronavirus mutating into feline infectious peritonitis virus.

Front 155

Most coronaviruses are monotypic (meaning that they have one serotype per species).

Back 155

True
This is a fundamental characteristic of coronaviruses.

Front 156

Which of the following is the least practical and effective measure you could take to help eradicate Equine viral arteritis (EVA) virus from a country in which it has become established?
a. Compulsory serological testing of all breeding stallions.
b. Virus isolation from semen of seropositive stallions to identify shedders.
c. Isolation of mares for 21 days after breeding to a seropositive stallion.
d. Compulsory serological testing of all breeding mares to detect carriers.
e. Vaccination of seronegative stallions serving alongside shedder stallions.

Back 156

d. Compulsory serological testing of all breeding mares to detect carriers.

EVA is most efficiently transmitted via the veneral route. Infected stallions can shed virus in semen
for months to years without any clinical signs.

Front 157

Only stallions can become permanent shedders of the Equine viral arteritis (EVA) virus.

Back 157

True
Colts or stallions infected by respiratory transmission of EVA can become permanent harbourers of EVA in their secondary sex glands, which causes the virus to be shed in their semen. The presence of testosterone is required in order for EVA to be harboured (therefore, it cannot be harboured in mares or geldings).

Front 158

The most important route of spread of infection with the Equine Viral Arteritis virus is horizontally through direct contact.

Back 158

False
The most important route for EVA infection is the veneral route, this is not necessarily direct contact since the virus is shed in semen and can spread to other animals through artificial insemination. Direct contact usually means aerosol transmission occurs (which is how permanent male shedders originally acquire the virus).

Front 159

Prompt post-exposure vaccination of humans against rabies can be protective. Given our current understanding of rabies pathogenesis, which of the following is the most plausible explanation for this?
a. The virus remains susceptible to immune attack for a period after exposure. Later, the virus begins to mutate and is able to evade the immune system by staying one step ahead.
b. The virus remains accessible to immune attack for a period after exposure. Later, the virus becomes latent in neurones and expresses only one latency-associated transcript.

d. The virus remains accessible to immune attack for a period after exposure, while it remains at the bite site. Once the virus enters neurons it becomes less accessible to the immune system.
e. The virus is carried to various internal organs via blood, before crossing the blood-brain barrier. It is during this primary viraemia that the virus can be cleared by the immune response to the rabies vaccine.

Back 159

d. The virus remains accessible to immune attack for a period after exposure, while it remains at the bite site. Once the virus enters neurons it becomes less accessible to the immune system.

Primary replication of the virus occurs in the muscle fibres at the site of inoculation. The virus aggregates around nerve endings only after this primary replication period, the further the inoculation (bite) site is from the CNS the longer the incubation period is.

Front 160

You are involved in organising veterinary field clinics in Africa. At one of such clinics, you are presented with a donkey that shows unusual behaviour – it seems very pruritic around its anus and repeatedly tries to bite at its right hind leg. The owner reports that the donkey started to behave strangely two days ago and seems to be getting worse. Choose the most likely explanation for the donkey’s behaviour and the best choice of action:
a. The donkey probably has a small wound on its leg causing the irritation –best option would be to perform a thorough physical exam and address any issues identified.
b. The donkey is probably infested with gastrointestinal parasites and is therefore pruritic and irritated. It should be properly examined and treated, if necessary.
c. The donkey displays clinical signs that are suggestive of rabies. Best to treat as potentially rabid and take all the appropriate precautions. The donkey should be euthanized, or isolated and kept under observation

Back 160

c. The donkey displays clinical signs that are suggestive of rabies. Best to treat as potentially rabid and take all the appropriate precautions. The donkey should be euthanized, or isolated and kept under observation

Rabid donkeys display furious behavioural changes: they become aggressive, restless, bite, have excessive salivation, exaggerated responses to light and sound, hyperaesthesia, and often can't swallow water. Dogs and cats also display furious signs while ruminants display dumb signs (depression, vocalisation, paralysis, incoordination).

Front 161

Which statement related to the reservoir hosts for rabies is least true?
a. Reservoir hosts maintain the rabies virus in the populations, as they do not become sick following infection, but still shed the virus in their saliva.
b. Different reservoir hosts are important in rabies epidemiology in different parts of the world.
c. It is possible to determine the source of rabies virus infection based on the analysis of the viral genome.
d. Vaccination of wildlife is an important part of rabies control efforts in many countries.
e. Potential reservoir host for rabies in New Zealand include dogs, cats, possums, or feral pigs.

Back 161

a. Reservoir hosts maintain the rabies virus in the populations, as they do not become sick following infection, but still shed the virus in their saliva.

All other choices are true. Reservoir hosts succumb to rabies, but the virus continues to be transmitted from individual to individual within the reservoir host population.

Front 162

Which of the following statements about Vesicular stomatitis virus (VSV) is least true?
a. Clinical signs of VSV infection in cattle are similar to foot-and-mouth disease.
b. VSV is exotic and notifiable in New Zealand.
c. VSV belongs to family Rhabdoviridae.
d. Similarly to the foot-and-mouth disease virus, VSV does not affect horses.
e. Uncomplicated cases of VSV typically resolve in 1-2 weeks.

Back 162

d. Similarly to the foot-and-mouth disease virus, VSV does not affect horses.

All other choices are true. Foot-and-mouth disease infects cloven-hoofed animals (cattle, sheep, goats, pigs, deer and many wild ruminants) whereas VSV infects horses, cattle, pigs, deer and humans (rarely). VSV does not infect sheep or goats.

Front 163

Which of the following vesicular viruses can infect both pigs and cattle?
a. San Miguel sea lion virus and Foot-and-mouth disease virus.
b. Vesicular exanthema of swine virus and Vesicular stomatitis virus.
c. Swine vesicular disease and Foot-and-mouth disease virus.
d. Vesicular stomatitis virus and Foot-and-mouth disease virus.
e. Foot-and-mouth disease virus and Vesicular exanthema of swine virus.

Back 163

d. Vesicular stomatitis virus and Foot-and-mouth disease virus.

All other choices are false. Vesicular stomatitis virus infects horses, cattle, pigs, and deer. San Miguel sea lion virus is also known as vesicular exanthema of swine disease, it infects pigs and has infected horses experimentally but not cattle. Foot-and-mouth disease virus causes disease in cloven-hoofed animals such as cattle, sheep, pigs, deer, and many wild ruminants.

Front 164

You are called to investigate a problem on one of your client's pig farms. The farmer reports increased numbers of lame pigs and a decrease in food intake. On arrival, you examine several pigs, which appear slightly depressed. Several of the pigs are febrile and some show vesicles and ulcers in the mouth and interdigital spaces. Infection with which virus(es) would be consistent with such a clinical picture?
a. Swine vesicular disease virus.
b. Foot-and-mouth disease virus.
c. Vesicular stomatitis virus.
d. a, b, or c.
e. a or b.

Back 164

d. a, b, or c.

Vesicular stomatitis virus presents a serious diagnostic problem because of its resemblance to other vesicular diseases, especially Foot and Mouth disease. Pigs with these clinical signs could be affected with vesicular stomatitis, foot-and-mouth-disease, swine vesicular disease, or vesicular exanthema of swine. Cattle are only affected with vesicular stomatitis or foot-andmouth disease. Other possible differential diagnoses for mouth lesions in cattle include Rinderpest, Mucosal Disease, and Malignant Catarrhal Fever. In pigs, photosensitization due to certain plant poisonings may also cause vesicles to be formed in the mouth.

Front 165

Which of the statements below regarding the ecology of terrestrial rabies is least true?
a. Rabies virus is maintained in different parts of the world in various reservoir hosts.
b. Reservoir hosts can shed the Rabies virus for prolonged periods of time (weeks to months).
c. Oral vaccination of wildlife against rabies has been successful in controlling rabies in Europe.
d. In addition to the Rabies virus, bats can be infected with several other zoonotic lyssaviruses.
e. Rabid dogs are common sources of exposure to the Rabies virus in developing countries.

Back 165

b. Reservoir hosts can shed the Rabies virus for prolonged periods of time (weeks to months).

All other choices are true. The virus is shed in saliva shortly before the onset of clinical signs, death occurs within 10-15 days of the onset of clinical signs. Therefore, prolonged shedding of the rabies virus is very unusual.

Front 166

You are working as a veterinarian in the USA and are called to examine a horse that is depressed and not eating well. You discover severe lesions in its mouth (pictured below). Several other horses on the same property showed similar lesions. Infection with which virus(es) should be on the top of your list of differential diagnoses?
a. Malignant catarrhal fever virus.
b. Foot-and-mouth disease virus.
c. Vesicular stomatitis virus.
d. b or c.
e. a, b or c.

Back 166

c. Vesicular stomatitis virus.

This picture is shown in the Rhabdoviridae lecture as vesicular stomatitis virus. Oral lesions can be caused by all diseases listed, however, horses have tranditionally been considered to be resistant to malignant catarrhal fever

Front 167

You are working as an aid veterinarian in a developing country and are bitten by a 3-month-old puppy brought by its owners for its free rabies vaccination. What would be the best way to deal with this accident?
a. You immediately clean the bite, then vaccinate the puppy. Later on, you contact the local physician and explain that you would like to undergo post-exposure prophylaxis for rabies, just in case.
b. Because of the possibility of rabies exposure, you had been vaccinated against rabies before you went on the aid trip. The puppy is young, so unlikely to have rabies, as rabies typically has a long incubation period. As such, you clean the bite, vaccinate the puppy and forget about the incident.
c. You clean the bite immediately. Instead of vaccinating, you euthanize the puppy and submit its head for rabies examination. If positive for rabies, you and other people in contact with the puppy will have to undergo post-exposure prophylaxis.

Back 167

b. Because of the possibility of rabies exposure, you had been vaccinated against rabies before you went on the aid trip. The puppy is young, so unlikely to have rabies, as rabies typically has a long incubation period. As such, you clean the bite, vaccinate the puppy and forget about the incident.

B? (Not sure) Veterinarians are at high risk for rabies exposure so they should be given a pre-exposure prophylactic vaccination. Rabies can have a long incubation period but it is also unlikely to be seen in a young puppy because the pup would not have had as much exposure to wild animals serving as reservoir hosts.

Front 168

The picture below shows a horse that presented with sudden onset of severe neurological signs. The horse is unable to stand and has to be supported in a sling. Which of the viral infections is unlikely to be the causative agent of this horse's problems?
a. West Nile virus.
b. Eastern equine encephalitis virus.
c. Rabies.
d. Japanese encephalitis virus.
e. Borna disease virus.

Back 168

e. Borna disease virus.

12. E? (Not sure) West Nile virus, Eastern Equine Encephalitis virus, and Japanese Encephalitis virus are all related viruses capable of infecting horses and causing neurological signs. Rabies should always be suspected in all equine cases that show a sudden onset of rapidly progressing neurological signs. Bornavirus causes neurological symptoms as well, hyperactivity and disturbances in gait are seen in early stages of infection which progress to ataxia/partial paralysis during the terminal stages of the disease.

Front 169

Rabies virus causes progressive neurological disease, which is invariably fatal in all warm-blooded animals.

Back 169

True
There have been a few reports of dogs, foxes, skunks and bats surviving infection and remaining carriers of the virus but this is regarded as a rare occurrence.

Front 170

Foot-and-mouth disease (FMD) in cattle is clinically indistinguishable from infection with the Vesicular stomatitis virus.

Back 170

True Vesicular stomatitis virus presents a serious diagnostic problem because of its resemblance to other vesicular diseases, especially Foot and Mouth disease. Other possible differential diagnoses for mouth lesions in cattle include Rinderpest, Mucosal Disease, and Malignant Catarrhal Fever.

Front 171

Numerous important fish diseases are caused by members of the rhabdoviridae family.

Back 171

True
Rhabdoviridae viruses cause rabies, vesicular stomatitis, bovine ephemeral fever, and exotic fish diseases.

Front 172

Rhabdoviruses are fragile in the environment, but will survive in cool, damp places.

Back 172

True
Rhabdoviruses are readily inactivated by UV light, heat, and detergents but can survive for longer periods in dark places at low temperatures (i.e. in caves and burrows). Rhabdoviruses can also persist in soil.

Front 173

Rabies virus belongs to the genus Vesiculovirus of the family Rhabdoviridae

Back 173

False Rabies belongs to the genus Lyssavirus.

Front 174

Vesicular stomatitis is often associated with profound hypocalcaemia.

Back 174

False Hypocalcaemia is not a diagnostic sign for this disease.

Front 175

Approximately half a million cattle deaths occur in South America each year, as a consequence of bat-associated rabies.

Back 175

True Bats act as a reservoir host for rabies in South America.

Front 176

Which of the following is most often associated with transmission of the Feline immunodeficiency virus (FIV) between cats?
a. Fighting.
b. Grooming.
c. Eating from a common bowl.
d. Drinking from a common bowl.
e. Sexual activity.

Back 176

a. Fighting.

The virus is shed in saliva, bite wounds from fighting are considered to be the major mode of transmission for FIV. Other modes of transmission do not appear to be important. There is a higher prevalence of FIV infection in male cats, presumably the result of the greater amount of fighting done by males.

Front 177

Abortion is the least common clinical presentation of infection with:
a. Bovine viral diarrhoea virus.
b. Akabane and Aino bunyaviruses.
c. Bluetongue virus.
d. Bovine immunodeficiency virus.
e. Rift valley fever virus.

Back 177

d. Bovine immunodeficiency virus.

BIV replicates in the immune cells of cows, experimentally infected calves develop a lymphocytosis which persists for several months but clinical immunodeficiency has not been demonstrated in experimentally infected animals. Current opinion is that BIV is probably not pathogenic but this remains to be confirmed.

Front 178

Retroviruses, in general, evolve rapidly and exhibit unusually frequent antigenic change. Which of the following is the least important reason for this?
a. The RT enzyme is highly error-prone.
b. The RT enzyme lacks 'proof-reading' capability.
c. Rapid replication under selective pressure from the immune system drives evolution.
d. A high rate of recombination occurs between retroviral genomes in doubly infected cells.
e. Recombination with endogenous retroviruses occurs frequently.

Back 178

e. Recombination with endogenous retroviruses occurs frequently.

All other answers are true. Endogenous retroviruses evolve very, very slowly.

Front 179

Consider this list of possible reasons for false positive and false negative diagnostic test results, some of which are relevant when testing cats for feline retroviral infections:
i. Healthy, 10 week old kitten born to an infected mother
ii. Recently vaccinated
iii. Recently infected
iv. Overwhelming, end-stage disease
v. Very mild disease
Which of these could plausibly cause a false negative result in a conventional 'in-practice' test for feline immunodeficiency virus?
a. (i).
b. (ii) & (iii).
c. (v).
d. (i) & (ii).
e. (iii) & (iv).

Back 179

c. (v). Very mild disease

After primary signs of infection have waned there is a long-lasting 'asymptomatic peri'd that may last for several years. Some cats persistently infected with FIV will never show clinical signs of infection and end up dying of other causes.

Front 180

Retroviruses:
a. Are present as endogenous viruses in some animals, but this is a rare situation which occurs due to integration of the exogenous virus into the host genome.
b. Are very stable and show a low rate of mutation due to the high proof-reading ability of the reverse transcriptase.
c. Are typically very infectious and can be easily c. transmitted by direct contact.
d. Are easily inactivated by common disinfectants and do not survive well outside the host.
e. Retroviral infection cannot be diagnosed using a single serum sample, as a positive result would indicate exposure to the virus in the past, and would not provide any information on the current infectious status of the animal.

Back 180

d. Are easily inactivated by common disinfectants and do not survive well outside the host.

Retroviruses are relatively fragile in the environment; therefore retroviruses require close contact for horizontal transmission.

Front 181

Which statement about Maedi/Visna virus infection is least correct?
a. Maedi presents a common problem in New Zealand sheep, while Visna is rarely seen.
b. Maedi/Visna is caused by a lentivirus.
c. Maedi and Visna relate to either pneumotropic or neurotropic isolates of the same virus.
d. Transmission occurs through contact with infected animals or contaminated feed/water, by inhalation or ingestion.
e. Because of the long incubation period, clinical disease is not diagnosed in sheep younger than 2 years.

Back 181

a. Maedi presents a common problem in New Zealand sheep, while Visna is rarely seen.

All other answers are true. Visna/Maedi is exotic to New Zealand and is considered a notifiable disease.

Front 182

Some cats are able to mount effective immune response to the Feline leukemia virus (FeLV) and clear infection with this retrovirus.

Back 182

True
The majority of adult cats (80-90%) and some young cats develop an effective immune response to FeLV and viraemia is terminated within one to two weeks. In approximately 66% of these cats the virus appears to be eliminated. Latent or sequestered infections occur in the cats that have not completely eliminated the virus.

Front 183

Feline immunodeficiency virus (FIV) is most often transmitted via prolonged direct contact, for example via grooming.

Back 183

False
The virus is shed in saliva, bite wounds from fighting are considered to be the major mode of transmission for FIV. Other modes of transmission do not appear to be important. There is a higher prevalence of FIV infection in male cats, presumably the result of the greater amount of fighting done by males.

Front 184

Endogenous retroviral sequences are present in most, if not all, mammalian genomes.

Back 184

True
A unique feature of retroviruses is their presence in the germ-line of many (perhaps all) vertebrates.

Front 185

Endogenous retroviruses are typically non-pathogenic.

Back 185

True Endogenous retroviruses are usually non-pathogenic. Often defective deletions or mutations have rendered them incapable of yielding infectious virus or the endogenous retrovirus is transcriptionally silent (i.e. not expressed as RNA/particles).

Front 186

Which of the following factors is least likely to affect the spread of the Bluetongue viruses?
a. Climate.
b. Presence of sheep.
c. Presence of cattle.
d. Presence of horses.
e. Presence of bodies of water.

Back 186

d. Presence of horses.

Bluetongue does not infect horses. The virus causes disease in sheep and subclinical or mild disease in goats, cattle, and wild ruminants (which form a reservoir of infection). The disease is spread by biting midges (particularly Cuilicoides spp.) so infection is generally confined to areas with a climate that can support midges. The presence of water provides a breeding site for the Cuilicoides vector.

Front 187

Which of the following factors are least important determinants of whether or not an arbovirus transmitted by midges will become established following inadvertent introduction to the new geographical area?
a. Presence of competent vectors.
b. Climatic conditions e.g. temperature, humidity, seasonality.
c. Presence of other arboviruses.
d. Presence of irrigated agriculture.
e. Density of susceptible hosts.

Back 187

c. Presence of other arboviruses.

All other answers are true. The presence of other arboviruses would have no impact on the transmission of a newly introduced arbovirus. Insect vectors are not limited to carrying only one disease at a time.

Front 188

Which of the following statements about alphaviruses is least true?
a. All are arboviruses, primarily a. mosquito-transmitted.
b. All are currently exotic to New Zealand except Whataroa virus.
c. Some can cause seasonal epidemics of equine and human encephalitis.
d. Competent vectors for some of these viruses are already present in New Zealand.
e. Vaccines have not yet been developed to protect against alphaviruses.

Back 188

e. Vaccines have not yet been developed to protect against alphaviruses.

All other answers are true. Vaccines for alphaviruses do exist and are particularly important for controlling the spread of Venezuelan equine encephalitis.

Front 189

Many arboviruses have evolved to be able to infect a wide range of vertebrate hosts. Which of the following is the most likely reason for this?
a. It is an inevitable consequence of their ability to infect animals as diverse as arthropods and vertebrates.
b. Virus-infected vectors of a given species may bite more than one vertebrate species.
c. Arboviruses are particularly ancient, they have co-evolved with a remarkably wide range of vertebrate hosts.
d. Virus-infected vertebrates of a given species may be bitten by more than one vector species.
e. Arboviruses are particularly 'new' viruses, many have not yet 'settled upon' a preferred vertebrate host.

Back 189

b. Virus-infected vectors of a given species may bite more than one vertebrate species.

Since arthropod vectors feed on many species of vertebrae the arboviruses which replicate in these vectors have evolved to have a wide host range which corresponds to the species the arthropod in question feeds upon.

Front 190

Which of the following diseases is not caused by an arbovirus?
a. Equine encephalomyelitis.
b. Rift Valley fever.
c. African swine fever.
d. Bluetongue.
e. Swinepox.

Back 190

e. Swinepox.

Poxviruses and equine infectious anaemia can be transmitted mechanically by arthropods but are not considered arboviruses. A virus must replicate in the arthropod to be considered an arbovirus (transmission is biological, not just mechanical).

Front 191

Which of the following is least likely to help control rotavirus diarrhoea in a group of calves?
a. Decreasing density of calves.
b. Vaccination of calves.
c. Avoiding chilling and stress.
d. Assuring adequate intake of colostrum.
e. Vaccination of pregnant cows.

Back 191

b. Vaccination of calves.

Inactivated vaccines are available for rotavirus but they may not fully protect against infection in calves. Vaccines used more for the purpose of reducing the excretion rate of the virus by adult cows.

Front 192

Which of the following factors play a role in the spread of the Bluetongue viruses?
a. Density of sheep.
b. Density of cattle.
c. Density of horses.
d. a and b.
e. a, b, or c.

Back 192

d. a and b.

Bluetongue does not infect horses. The virus causes disease in sheep and subclinical or mild disease in goats, cattle, and wild ruminants (which form a reservoir of infection).

Front 193

There are three known serotypes of the Bluetongue virus.

Back 193

False
The study guide currently estimates that there are about 24 different serotypes of bluetongue virus. The large number of serotypes is problematic for the development of an effective 'broad-spectrum' vaccine.

Front 194

Rotaviruses are common causes of diarrhoea in young animals of many species.

Back 194

True
Rotaviruses are important causes of neonatal diarrhoea in most species including humans.

Front 195

Arboviruses are mechanically transmitted by arthropods.

Back 195

False
Transmission by arboviruses is biological transmission. This means that the virus replicates in the gut of the arthropod and is later secreted in the saliva of the arthropod. This differs from mechanical transmission of some viruses by arthropods. With mechanical transmission, the arthropod is merely picking up the virus from one animal and transferring it to another (the virus does not replicate in the arthropod). Some examples of viruses mechanically transmitted by arthropods include: myxomatosis, fowlpox, and equine infectious anaemia.

Front 196

There are many serotypes of the Bluetongue virus, with little cross-protection between them.

Back 196

True
There are around 24 different serotypes of the Bluetongue virus. Serotypes are deined by cross-neutralisation tests. The large number of serotypes is problematic for the development of an effective 'broad-spectrum' vaccine. When vaccinating animals against Bluetongue, it is necessary to have a good knowledge of the serotypes of virus present in a particular area (the appropriate strain must be targeted).

Front 197

Infection with the African horse sickness virus in Zebras is typically fatal.

Back 197

False
African horse sickness causes 0% mortality in zebras. Elephants and zebras are thought to be reservoirs for the disease. The most likely method of introduction of the virus into new areas is through clinically normal but viraemic zebras imported from Africa into zoos.

Front 198

Mucosal immunity plays little role in protection from infection with rotaviruses.

Back 198

False?
When calves are inoculated with rotavirus there is a local immunoglobulin A response, most of the rotavirus antibody-producing cells will be found in the mucosa of the proximal small intestine.

Front 199

African swine fever virus is the only DNA virus that is also an arbovirus.

Back 199

True
African swine fever is the only DNA virus that is also an arbovirus. It replicates within and is transmitted by soft ticks.

Front 200

The African horse sickness virus is an arbovirus.

Back 200

True
African horse sickness virus is a true arbovirus.

Front 201

Sheep serve as maintenance hosts for Bluetongue viruses.

Back 201

False?
Sheep are considered the most vulnerable species for Bluetongue. Maintenance hosts are able to transmit the virus with little sign of disease. Cattle are likely to be an important maintenance host since the Cuilicoides vector species feeds more abundantly on cattle.Wild ruminants are also important since they remain viraemic for a longer period of time than cattle but have mild symptoms.

Front 202

Which of the following statements regarding bunyaviruses is least true?
a. Abortion is a common clinical feature of many bunyavirus infections.
b. Most of bunyaviruses are arboviruses.
c. Bunyaviruses survive well outside their hosts and are difficult to disinfect.
d. Some bunyaviruses can cause life-threatening infections in humans.
e. Bunyavirus activity is often associated with local climatic conditions.

Back 202

c. Bunyaviruses survive well outside their hosts and are difficult to disinfect.

All other choices are true. Most bunyaviruses are arboviruses which suggests that they are relatively fragile (since they require an insect vector to be spread). Bunyaviruses have a lipid envelope which makes them somewhat fragile (the envelope can be destroyed by fat solvents like alcohol, ordinary disinfectant and household bleach).

Front 203

Immunosuppression is an important clinical feature seen in chickens infected with Infectious bursal disease virus (IBDV).

Back 203

True
IBDV selectively replicates in and destroys pre-B lymphocytes in the developing Bursa of
Fabricus (the virus is grown in chicken embryos so any chicks that survive will be far more
susceptible to secondary infection).

Front 204

Rift valley fever virus can cause abortions in a variety of species, including humans.

Back 204

True
Rift valley fever infects sheep, cattle, goats, and humans. It is capable of causing abortion
through a secondary viraemia which involves the uterus and conceptus of pregnant animals
(primary viraemia targets liver and phagocytes).

Front 205

People can become infected with hantaviruses through contact with rodents or rodent-infested places.

Back 205

True
Humans may be infected with hantaviruses through rodent bites, faeces, urine, saliva or
contact with rodent waste products.

Front 206

Living in rodent-infested places is a risk factor for hantavirus infection.

Back 206

True
Humans may be infected with hantaviruses through contact with rodent waste products (i.e.
urine, faeces, saliva).

Front 207

Which of the following measures is least likely to be effective in minimizing the economic effects of Bovine viral diarrhea (BVD) infection in a herd?
a. Blood-testing all the bulls for BVD antigen, followed by yearly vaccination of BVDnegative bulls.
b. Separation of persistently-infected animals from the rest of the herd in a designated paddock.
c. Vaccination of all heifers against BVD.
d. Identification and removal of persistently infected animals.
e. Good biosecurity, including disinfection, traffic control and record keeping.

Back 207

b. Separation of persistently-infected animals from the rest of the herd in a designated paddock.

Close contact with individually infected cattle is not necessary as infection is via the oropharnyngeal route from material contaminated by infected faeces, urine, or oral/nasal secretions. Also, the expense involved in using a screening programme is quite high so vaccination is often used in preference to testing schemes.

Front 208

Mucosal disease:
a. Results from co-infection of a persistently infected calf with a cytopathic strain of Bovine viral diarrhoea (BVD) virus.
b. Results from a mutation of a non-cytopathic strain of the BVD virus in persistently infected calves.
c. Results from infection with the BVD-2 virus, which is more virulent than BVD-1 virus.
d. Either a or b.
e. Either a, b, or c.

Back 208

d. Either a or b.

A and B are both true. C is false, BVD-2 is more virulent than BVD-1 but it causes haemorrhagic disease (bleeder syndrome). Mucosal disease results when persistent BVD carriers are infected with a second, more aggressive strain of pestivirus (cytopathic or "mutant" BVD virus).

Front 209

Infection with the Bovine viral diarrhoea (BVD) virus at around two
months of gestation is most likely to result in:
a. Death of the foetus and abortion.
b. Birth of a calf with congenital defects.
c. Birth of a healthy calf with immunity to subsequent BVD infections.
d. Birth of a persistently infected calf, which will never clear the virus.
e. Birth of a persistently infected calf, which may occasionally clear the virus in the first few months of life.

Back 209

e. Birth of a persistently infected calf, which may occasionally clear the virus in the first few months of life.

Infection in a pregnant cow between 40-120 days gestation leads to the development of a persistently infected foetus that is immunologically tolerant. Most calves born like this do not live to maturity because they usually succumb to Mucosal disease between 6 to 18 months of age.

Front 210

You are working in an equine hospital in central USA and are caring for a horse with severe neurological disease, which has been diagnosed as a West Nile virus (WNV) infection. Your veterinary nurse is concerned about the risk of catching the disease from this horse. Choose the best answer.
a. West Nile virus does not infect humans, and thus there is no risk to people who care for the horse.
b. West Nile virus is a zoonotic disease transmitted by close contact with infected animals. Technical staff caring for this horse is at risk for infection and should be vaccinated against WNV.
c. West Nile virus is a zoonotic disease, but it is transmitted by infected mosquitoes, not by direct contact with the infected horse.
d. Human and equine strains of WNV differ, and people cannot become infected with an equine strain.
e. The horse was infective only at the beginning of its illness – by the time clinical signs are apparent the virus is no longer present in its secretions.

Back 210

c. West Nile virus is a zoonotic disease, but it is transmitted by infected mosquitoes, not by direct contact with the infected horse.

West Nile virus is an arbovirus which needs to replicate within mosquitoes before being transmitted to secondary/incidental horses (i.le. Humans, horses, animals other than bird reservoirs).

Front 211

Infection of a non-immune, pregnant cow with Bovine viral diarrhoea virus between 180 and 190 days post-conception would be most likely to lead to which of the following consequences?
a. An antigen positive, immunotolerant, healthy calf is born.
b. A normal-sized calf is born dead.
c. A calf with congenital defects of the CNS (e.g., cerebellar hypoplasia) is born.
d. An antibody positive, virus-free, normal calf is born.
e. The cow aborts within 3-4 days of infection.

Back 211

d. An antibody positive, virus-free, normal calf is born.

If the cow is infected with BVD after it is more than 150 days pregnant then a normal calf is born with no virus due to a competent immune response within the foetus but will test positive for antibodies due to the presence of maternal antibodies.

Front 212

Which of the following statements about alphaviruses is least true?
a. All are arboviruses, primarily mosquito-transmitted.
b. All are currently exotic to New Zealand except Whataroa virus.
c. Some can cause seasonal epidemics of equine and human encephalitis.
d. Competent vectors for some of these viruses are already present in New Zealand.
e. Vaccines have not yet been developed to protect against alphaviruses.

Back 212

e. Vaccines have not yet been developed to protect against alphaviruses.

All other answers are true. Vaccines for alphaviruses do exist and are particularly important for controlling the spread of Venezuelan equine encephalitis.

Front 213

You are investigating a problem on a 600-cow dairy farm. The farmer reports an increase in the number of cows that return to oestrus following mating, a decrease in milk production and an increased number of
abortions. The farmer wants to know whether or not he has a problem with Bovine viral diarrhoea (BVD) in his herd. What initial testing options could you suggest to the farmer to determine the BVD status of the herd?
a. Test composite milk samples for the presence of BVD antibody.
b. Test composite milk samples for the presence of BVD antigen.
c. Blood-test each individual cow for BVD antigen. Start with lowest producing cows.
d. a or c.
e. a, b, or c.

Back 213

b. Test composite milk samples for the presence of BVD antigen.

(Not sure) Persistently infected animals are antibody negative so testing for antibody would not reveal the presence of any PI cows (however, it is reasonable to assume that all PI cows die in 6-18 months before they are regularly milked). Blood-testing each individual cow is not a cost effective initial test.

Front 214

Which of the following measures is least likely to prevent introduction of BVD-virus to a BVD-negative herd?
a. Introduce only non-pregnant, BVD-antigen negative animals to the herd.
b. Introduce only non-pregnant, BVD-antibody positive animals to the herd.
c. Introduce only BVD-antibody negative animals to the herd.
d. Use only BVD-tested and vaccinated bulls.
e. Maintain good biosecurity.

Back 214

c. Introduce only BVD-antibody negative animals to the herd.

(Not sure) The herd is BVD negative so B is not a good idea (since animals with BVD antibodies have been exposed to BVD at some point). C is also not a good idea since persistently infected animals may not show antibodies for BVD. Also, it may be a good idea to only allow non-pregnant animals into the herd since having a pregnant animal could increase the risk of having a persistently infected calf (which is why B is probably ok).

Front 215

African swine fever (ASF) is exotic to New Zealand, but Classical swine fever (CSF) is a common infection in New Zealand pigs.

Back 215

False
Both diseases are exotic to New Zealand and notifiable.

Front 216

Mucosal disease results from infection of young cattle with a more virulent strain of the Bovine viral diarrhoea (BVD) virus.

Back 216

False
Mucosal disease occurs in calves persistently infected with BVD which are then exposed to a more aggressive strain of BVD (cytopathic BVD).

Front 217

The natural reservoir for Equine encephalitis viruses are horses.

Back 217

False Horses are dead-end hosts (they die when infected with EEE). The reservoir hosts for EEE are birds (Culiseta melanura) which mosquitoes feed on (the virus replicates within mosquitoes as this is an arbovirus).

Front 218

You are involved in containing a Foot-and-mouth disease (FMD) virus outbreak in the UK. Which of the measures below would you consider least effective in trying to stop the spread of the virus?
a. Disinfection of affected premises and equipment with a citric acid-based disinfectant.
b. Ring vaccination of healthy cattle and pigs with a vaccine directed against the outbreak serotype of FMD virus.
c. Isolation of infected animals in a fenced paddock, with at least 50 meters clearance around the perimeter of the paddock.
d. Test-and-slaughter policy.
e. Implementation of the animal movement control within the affected area.

Back 218

c. Isolation of infected animals in a fenced paddock, with at least 50 meters clearance around the perimeter of the paddock.

Option C is ineffective compared to the other choices because carriage of the virus by migrant birds and wind-borne aerosols has been demonstrated. FMD is a hardy virus which can persist in the environment for a long period of time and can spread up to 100-200km just by airborne transmission.

Front 219

Which of the following features of the Foot-and-mouth disease (FMD) virus is least likely to contribute to the rapid spread of the virus?
a. High virus titres in respiratory secretions.
b. Shedding of the virus before development of clinical signs.
c. High stability of the virus in wide range of pH.
d. High contagiousness of the virus.
e. Ability to infect several species.

Back 219

c. High stability of the virus in wide range of pH.

This answer is false, FMD virus is sensitive to acidic conditions. Infectivity of the virus is rapidly lost at pH5 (pH of citric acid).

Front 220

Which of the following statements regarding Foot-and-mouth disease (FMD) virus is least true?
a. The FMD virus is very stable in many environmental conditions.
b. The FMD virus can be transmitted by wind over long distances.
c. Infected animals shed large quantities of virus.
d. Shedding of the FMD virus begins after development of clinical signs.
e. The FMD virus is very infectious.

Back 220

d. Shedding of the FMD virus begins after development of clinical signs.

All other answers are true. FMD virus is shed from its primary replication site (usually the epithelium of the upper respiratory or alimentary tract) before the incubation period is over.

Front 221

Which of the following vesicular viruses can infect both pigs and cattle?
a. San Miguel sea lion virus and Foot-and-mouth disease virus.
b. Vesicular exanthema of swine virus and Vesicular stomatitis virus.
c. Swine vesicular disease and Foot-and-mouth disease virus.
d. Vesicular stomatitis virus and Foot-and-mouth disease virus.
e. Foot-and-mouth disease virus and Vesicular exanthema of swine virus.

Back 221

d. Vesicular stomatitis virus and Foot-and-mouth disease virus.

All other choices are false. Vesicular stomatitis virus infects horses, cattle, pigs, and deer. San Miguel sea lion virus is also known as vesicular exanthema of swine disease, it infects pigs and has infected horses experimentally but not cattle. Foot-and-mouth disease virus causes disease in cloven-hoofed animals such as cattle, sheep, pigs, deer, and many wild ruminants.

Front 222

Foot-and-mouth disease (FMD) in cattle is clinically indistinguishable from infection with the Vesicular stomatitis virus.

Back 222

True
Vesicular stomatitis virus presents a serious diagnostic problem because of its resemblance to other vesicular diseases, especially Foot and Mouth disease. Pigs with these clinical signs could be affected with vesicular stomatitis, foot-and-mouth-disease, swine vesicular disease, or vesicular exanthema of swine. Cattle are only affected with vesicular stomatitis or foot-and mouth disease. Other possible differential diagnoses for mouth lesions in cattle include Rinderpest, Mucosal Disease, and Malignant Catarrhal Fever. In pigs, photosensitization due to certain plant poisonings may also cause vesicles to be formed in the mouth.

Front 223

Foot-and-mouth disease virus is easily destroyed by low pH.

Back 223

True FMD virus is sensitive to acidic conditions. Infectivity of the virus is rapidly lost at pH5 (pH of citric acid).

Front 224

Pigs are considered "amplifier" hosts for the foot-and-mouth disease virus.

Back 224

True
Pigs act as amplifier hosts as infected pigs have amazingly high virus output. Cattle act as indicator hosts since infection of cattle results in severe disease manifestations. Sheep act as maintenance hosts as infection of sheep causes only mild or subclinical disease. A number of wild ruminants are also involved in the epizootiology of FMD within Africa.

Front 225

Aphtoviruses, such as the foot-and-mouth disease virus, are unstable in pH below 7.0 and can be easily disinfected by acidic solutions.

Back 225

True FMD virus is sensitive to acidic conditions. Infectivity of the virus is rapidly lost at pH5 (pH of citric acid).

Front 226

Infectious Foot-and-mouth disease virus can be carried by wind over long distances.

Back 226

True
Airborne spread of up to 100-200km has been demonstrated for this virus.

Front 227

Most young rabbits up to 8 weeks of age are resistant to rabbit calicivirus disease (RCD). From what is known so far, what is the most plausible and precise explanation for this observation?
a. Most are protected by maternally-transferred passive immunity.
b. They lack specific receptors for the virus. They are neither infected nor immune after exposure to the virus.
c. They have immature hepatocytes and therefore cannot be infected by the virus.
d. They do become infected and mount an immune response, but, for reasons that remain unclear, they do not become seriously ill as a consequence.
e. Resistance relies upon the fact that most of these young rabbits are born to dams that were, themselves, exposed to the virus when at a disease-resistant stage.

Back 227

d. They do become infected and mount an immune response, but, for reasons that remain unclear, they do not become seriously ill as a consequence.

The specific mechanism is not known but it is definitely not due to maternal immunity. It is speculated that either the clotting mechanism required to initiate DIC is lacking in young rabbits, or that the susceptibility of hepatocytes to this virus is dependent on hepatic transaminases which are deficient in young rabbits.

Front 228

Currently-available Feline calicivirus (FCV) vaccines do not provide complete protection against this virus. The most likely reason for this is:
a. Most kittens have already been infected before the vaccine can take effect.
b. Cross-protection between vaccinal strains and strains present in the community is incomplete.
c. The virus evolves rapidly, so that this year's vaccine may not protect against next year's virus.
d. Vaccine-induced immunity against this particular virus is short-lived, often less than a full year.
e. Carriers may intermittently shed large amounts of virus, overwhelming the immune response to vaccination.

Back 228

b. Cross-protection between vaccinal strains and strains present in the community is incomplete.

Feline calicivirus vaccines provide long-lasting immunity and require annual booster shots but the vaccine may not contain the relevant strain. Note that intermittent shedding does not occur (see choice E), this is a property of herpesviruses.

Front 229

Immunity to Feline calicivirus is stronger and longer lasting than immunity to Feline panleukopenia virus following either vaccination or natural infection.

Back 229

False
Feline panleucopenia virus vaccine does not need to be administered again after its final booster shot given at 12 months of age. Feline calicivirus vaccines need annual booster shots.

Front 230

Which of the following statements about Borna disease virus is least true?
a. It is the only known member of the family Bornaviridae.
b. It can cause devasting epizootics of fatal neurological disease in horses and sheep.
c. Intranasal infection is thought to be important in the epizootiology.
d. It may cause neuropsychiatric illness in humans.
e. Several rodent reservoir hosts have been characterised.

Back 230

e. Several rodent reservoir hosts have been characterised.

All other answers are true. The study guide says that it is unknown if reservoir hosts are involved in the transmission of Borna disease virus.

Front 231

Borna disease virus causes severe neurological disease in all infected horses.

Back 231

False
Borna disease virus causes death in 90% of affected animals within 1-3 weeks.

Front 232

For bovine spongiform encephalopathy, which of the following is the least important difference between PrPSC and PrPC?

a. PrPSC is more protease resistant than PrPC.
b. PrPSC polymerises more efficiently than PrPC.
c. PrPC and PrPSC are encoded on different alleles.
d. PrPSC is much more heat resistant than PrPC.
e. PrPC and PrPSC are different isoforms of a protein.

Back 232

c. PrPC and PrPSC are encoded on different alleles.

All are true, but inheritance probably has less of an impact on the spread of BSE than the ingestion of the BSE prion.

Front 233

Which of the following is the most significant difference between new variant Creutzfeldt-Jakob disease and other 'classical' forms of the disease?

a. The new variant form attacks older people.
b. The new variant form is associated with a longer course of illness.
c. The new variant form is continuing to increase in incidence compared with the other forms.
d. The new variant form cannot be transmitted iatrogenically.
e. The new variant form cannot be transmitted to macaques and closely-related primates.

Back 233

b. The new variant form is associated with a longer course of illness. OR
c. The new variant form is continuing to increase in incidence compared with the other forms.

The other choices are untrue (unsure about D). B seems more significant than C.

Front 234

Which of the statements below regarding prions is least true?

a) Certain genotypes of sheep are associated with resistance to scrapie.
b) Abnormal prion proteins (PrPSC) are extremely resistant, and survive conditions that would kill even the "hardiest" viruses.
c) Unlike normal prion proteins, PrPSC are not naturally destroyed by the cell. Instead, they accumulate within the cell and eventually kill it.
d) There are many "strains" of prion proteins, which can be differentiated by the length of the incubation period, type and distribution of brain lesions produced in mice.
e) All transmissible spongiform encephalopathies result from infection with an abnormal form of the prion protein, typically acquired through the food chain.

Back 234

a) Certain genotypes of sheep are associated with resistance to scrapie.

All other choices are true.

Front 235

Transmissible spongiform encephalopathies may be:

a. Sporadic (unknown cause).
b. Infectious - spread horizontally either by direct contact or by contaminated feed.
c. Genetic - occurring due to a mutation in a PrPC gene.
d. All of the above.
e. a or b.

Back 235

d. All of the above.

B and C are true so it must be D.

Front 236

Transmissible spongiform encephalopathies:

a. Are caused by viruses from the family Bornaviridae.
b. Are common in young animals with neurological disease.
c. Have been described to be transmitted by arthropod vectors.
d. Cause progressive neurological disease in a number of animal species.
e. Can be prevented by vaccination.

Back 236

d. Cause progressive neurological disease in a number of animal species.

All other choices are false.

Front 237

Transmissible spongiform encephalopathies:

a. Are caused by viruses from the family Bornaviridae.
b. Can be diagnosed by serological testing before development of clinical signs.
c. Are more common in young animals than in old ones.
d. Cause progressive neurological disease in a number of animal species.
e. Can be prevented by vaccination.

Back 237

d. Cause progressive neurological disease in a number of animal species.

All other choices are false.

Front 238

Which of the following factors is least likely to contribute to difficulties associated with control of prion diseases (spongiform encephalopathies)?

a. There is no recognisable immune response to prion proteins.
b. There is typically a long incubation period.
c. Prion proteins are externally difficult to inactivate.
d. Prion proteins are easily transmitted between different animal species.
e. Ante-mortem diagnosis of spongiform encephalopathies is difficult.

Back 238

d. Prion proteins are easily transmitted between different animal species.

Many prion proteins are species specific.

Front 239

Which of the following viruses is present in animals living in New Zealand?

a. Caprine arthritis-encephalitis virus.
b. Equine influenza virus.
c. Louping ill virus.
d. Equine infectious anaemia virus.
e. Ovine pulmonary adenomatosis virus.

Back 239

a. Caprine arthritis-encephalitis virus.

The prevalence of this virus is around 1.8% in New Zealand. It occurs mainly in dairy goats, and to a lesser extent Angros and farmed feral goats.

Front 240

Which of the following viruses is present in New Zealand?
a. Porcine parvovirus.
b. Highly pathogenic avian influenza.
c. Velogenic Newcastle disease.
d. Classical swine fever.
e. Equine influenza.

Back 240

a. Porcine parvovirus.

Porcine parvovirus has a worldwide distribution and is present in most countries including New Zealand.

Front 241

Which of the following viruses cannot be transmitted to humans?
a. West Nile virus.
b. Orf virus.
c. Yellow fever virus.
d. Pseudorabies virus.
e. Foot-and-mouth disease virus.

Back 241

d. Pseudorabies virus.

Pseudorabies can be transmitted from pigs to a number of other animals but it is not zoonotic as it does not infect humans.

Front 242

Which of the following virus families are very small viruses that require actively dividing cells for replication? Choose all correct answers (there may be more than one).
a. Poxviridae.
b. Herpesviridae.
c. Circoviridae.
d. Papillomaviridae.
e. Parvoviridae.

Back 242

c. Circoviridae.
e. Parvoviridae.

Parvovirus and circovirus are the smallest DNA viruses, parvovirus always requires actively dividing cells, and circovirus also requires actively replicating cells.

Front 243

Which of the following virus families are large viruses that are fragile in the environment? Choose all correct answers (there may be more than one).
a. Asfarviridae.
b. Herpesviridae.
c. Adenoviridae.
d. Papillomaviridae.
e. Circoviridae.

Back 243

b. Herpesviridae.

All other virus familes listed are resistant in the environment.

Front 244

Which of the following virus families have been proven to cause carcinomas? Choose all correct answers (there may be more than one).
a. Rhabdoviridae.
b. Circoviridae.
c. Orthomyxoviridae.
d. Papillomaviridae.
e. Parvoviridae.

Back 244

d. Papillomaviridae.

Papillomaviridae, Retroviridae, and Hepnaviridae are virus families known to cause cancer in animals and humans.