Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
257 Cards in this Set
- Front
- Back
|
Is the following statement true or false? A parasite with a short Pre-patent period is more likely to allow hosts to reinfect themselves whilst they are still permissive. |
True |
|
|
Which one of the following definitions provides the correct definition of the term Pre-patent period (PPP)? Select one: a. The time required for development of infective stages in the environment b. The time taken from infection of the host to the onset of clinical signs c. The time take from infection of the definitive host to the point at which eggs, sometimes larvae start being shed d. The time required for the full lifecycle to be completed (egg-laying adult to egg-laying adult) |
C. The time taken from infection of the definitive host to the point at which eggs, sometimes larvae start being shed. |
|
|
Which of the following infection routes cannot be utilised by an ascarid nematode such as Toxocara canis? Select one: a. Ingestion of milk from the mother containing larvae b. Migration of larvae across the placenta c. Ingestion of developed eggs d. percutaneous invasion by larvae e. Ingestion of larvae in a paratenic host such as a mouse |
D. Percutaneous invasion by larvae Developed ascarid eggs will not hatch unless they are ingested. With no 'free-wriggling' stage present in the environment, penetration by larvae across the skin cannot occur.
|
|
|
What is the optimum temperature for the survival of the infective stage of nematodes in the strongylid order? Select one: a. -5 degrees centigrade b. 0 degrees centigrade c. 5 degrees centigrade d. 10 degrees centigrade e. 15 degrees centigrade f. 20 degrees centigrade g. 25 degrees centigrade h. 30 degrees centigrade |
D. 10 degrees centigrade |
|
|
Infection of humans with larvae of the canine hookworms is typically called: Select one: a. cutaneous larva migrans b. visceral larva migrans c. larva currens |
a. cutaneous larva migrans |
|
|
What is the minimum temperature for the development of nematodes in the strongylid order, below which no development occurs? Select one: a. 0-4 degrees centigrade b. 5-10 degrees centigrade c. 11-15 degrees centigrade d. 16-20 degrees centigrade e. 21-25 degrees centigrade f. 26-30 degrees centigrade g. 31-35 degrees centigrade |
b. 5-10 degrees centigrade |
|
|
In temperate climates like New Zealand's, when lambs are set stocked, the numbers of infective strongylid larvae on the pasture often decrease in summer, why does this happen? Select one: a. there is too much rainfall washing larvae into the soil b. temperatures get too hot in summer, causing accelerated mortality of developing larvae c. there is often not enough rainfall and larvae die due to desiccation d. the New Zealand summer is not warm enough to promote successful development |
c. there is often not enough rainfall and larvae die due to dessication Dry conditions in summer are typically responsible for lower pasture larval levels at this time, even though temperatures would favour rapid development. The numbers of infective larvae on pastures typically rise again after the rains return in autumn. |
|
|
Is the following statement true or false? If we are concerned with whether a dog we have treated for hookworm and whipworm has been reinfected with both worms, then we can check a faecal sample one month after treatment to see if eggs have reappeared. |
False The PPP of hookworms in dogs (e.g. Uncinaria stenocephala) is about 2 weeks whilst that of whipworm (Trichuris vulpis) is 10 weeks. Therefore we could only confirm reinfection with hookworm and must wait longer before we could detect whipworm. |
|
|
What is the optimum temperature for the development of the infective stage of nematodes in the strongylid order? Select one: a. 5-7 degrees centigrade b. 10-12 degrees centigrade c. 15-17 degrees centigrade d. 20-22 degrees centigrade e. 25-27 degrees centigrade f. 30-32 degrees centigrade g. 35-37 degrees centigrade |
e. 25-27 degrees centigrade |
|
|
Is the following statement true or false? In the US and Australia, dogs are more likely to be infected with heartworm (Dirofilaria immitis) in summer. |
True. Mosquitoes, the intermediate host for heartworm are indeed more active in summer. |
|
|
Describe the mode of action of Pyrantel and its derivatives |
Act as cholinergic agonists -> paralysis. Bind to limited range of cholinergic receptors but usually sufficient to kill nematode. Pyrantel and morantel exist in different salts that affect their solubility and efficacy against some nematodes. Tartrate and citrate salts are water soluble and absorbed. Broad spectrum activity against most GIT nematodes (some against cestodes). Pyrantel (cats and dogs), morantel (horses and ruminants). Oxantel (mixed with pyrantel) used to target Trichuris in dogs. |
|
|
List the 5 recognized action families of anthelmintics |
Benzimidazoles (BZs) Macrocyclic lactones (MLs/Avermectins,milbemycins) levamisole (LEV)/ morantel aminoacetonitrile derivatives (AADs) Spiroindoles |
|
|
True or false: Levamisoles can't be used on horses because the toxic and the therapeutic doses are too close. |
True. |
|
|
Explain, in simple terms, the mode of action of organophosphates |
OP act as anticholinesterases. More often used as an ectoparasiticide/insecticide |
|
|
Explain in simple terms the mode of action of levamisole |
Levamisole is a broad spectrum anthelmintic for GIT and respiratory nematodes but not cestodes or trematodes. It exists as different salts. For oral dosing it is usually the HCl salt but for injection usually phosphate salt. They act as cholinergic agonists -> paralysis. Affect different receptors to other anthelmintics and only act on a limited range -> sufficient to kill. Resistance attributed to decrease in susceptible ACh receptors, replaced with insusceptible receptors. |
|
|
Explain in simple terms the mode of action of macrocyclic lactones and the pharmacokinetics of those with persistent activity. (Avermectin/Milbemycins) |
Effective against most nematodes and arthopods but not cestodes or trematodes. (Endoectocides). They bind to glutamate-gated chloride ion channels on nerves -> allow Cl- into nerve -> hyperpolarise nerve -> unable to generate AP -> paralysis. Binding to GABA receptors also important for killing arthropods. Very lipophilic and chemical is absorbed into lipid depots and released over time giving persistent activity (especially moxidectin) -> leads to high blood levels -> persistent activity on "easier to kill nematodes" (T. circumcincta and H. contortus.. depsite being resistant to ivermectin). Abamectins are slightly more potent than ivermectin against easy to kill species but slightly less so than moxidectin. Abamectin and ivermectin do not have persistent activity. |
|
|
Explain in simple terms the mode of action of benzimidazoles. |
"White drenches". Insoluble so are opaque. Binds to tubulin and interferes with the polymerisation and formation of microtubules in the cells -> important for intracellular skeleton and cell division. Have been modified so their elimination is slower -> increased efficacy. Pro-BZs = metabolised by body to BZs. Effective against most GIT nematodes, and some cestodes and trematodes. Good safety rating. In ruminants bind to particulate matter and is released mainly further down GIT. Resistance due to loss of tubulin with high affinity receptor sites for BZs. |
|
|
Explain in simple terms the mode of action of aminoacetonitrile derivatives (AADs) |
It is a cholinergic agonist with activity directed directed through a unique ACh receptor which is different to the ones targeted by LEV/morantel/pyrantel. This receptor appears to be unique to nematodes which implies it is safer than some other cholinergic agonists. Effective against all GIT strongylid nematodes but poor against Dictyocaulus and no activity against Trichuris. |
|
|
Explain in simple terms the mode of action for Spiroindoles (derquantel). |
Derquantel = synthetic derivative of paraherquamide. It is a cholinergic antagonist and blocks transmission of impulses between nerves and muscles. ie. in a different way to BZs and MLs. Action raises question about difference from LEV and AADs -> evidence indicates it is involved with diff. set of of receptors to both and as an antagonist works somewhat differently. |
|
|
Describe what is meant by an "action family" |
A group of anthelmintics that have the same or a similar mode of action. |
|
|
Which broad spectrum anthelmintics fall into the Benzimidazole action family? |
Fenbendazole, oxfendazole, mebendazole, albendazole, oxibendazole. Pro-benzimidazoles include: febantel, thiophonate, netobimin |
|
|
Which broad spectrum anthelmintics fall into the Macrocyclic lactones action family? |
ivermectin, doramectin, abamectin, eprinomectin, moxidectin, selamectin, milbemycin oxime (last two are used in small animals) |
|
|
Which broad spectrum anthelmintics fall into the levamisole/morantel action family? |
levamisole, morantel, pyrantel, oxantel |
|
|
Which broad spectrum anthelmintics fall into the aminoacetonitrile derivatives (AADs) action family? |
Zolvix |
|
|
Which broad spectrum anthelmintics fall into the spiroindoles action family? |
Derquantel |
|
|
Which anthelmintics are known to increase their efficacy by slowing their metabolism down or by requiring the effective anthelmintic to be metabolised from a "pro-drug"? |
Benzimidazoles = slowed metabolism and use of "pro-drug". Moxidectin (ML) stores itself in fat depots (lipophilic) and so can be released slowly from these -> persistent presence in the blood and therefore persistent activity. |
|
|
Define 'withholding period' and describe its purpose |
Definition: Time following use of a drug for which milk or meat may not be used for human consumption. This is in place to minimise any toxicity to humans from the anthelmintic residues possibly left over in the milk or muscles of the animal. |
|
|
Describe how a controlled release capsule for ivermectin or albendazole in sheep works |
Wings stop bolus moving back up during rumination - sits in rumen. Spring inside casing drives pellets containing active ingredient down to small opening where ruminal fluid will dissolve them slowly. Provides continuous low-level release for 100 days. About 10% of standard oral dose/day. |
|
|
List the advantages of controlled release capsule anthelmintics for sheep |
Slow-release means that the drug will kill existing nematodes and prevent establishment of incoming larvae. Reduces the amount of drenching needed annually. |
|
|
List the disadvantages of controlled release capsule anthelmintics for sheep |
Have witholding period (for some) and so prevents sale of wet/dry ewes for slaughter if been treated. Easy to administer them wrong and cause death |
|
|
Describe the general mode of action and pharmacokinetics of niclosamide |
Chlorinated salicylanilide. Almost not absorbed by the host. Acts by disturbing mitochondrial energy metabolism of the cestode. Effective against most cestodes but no longer available in NZ |
|
|
Describe the general mode of action and pharmacokinetics of praziquantel |
Effective against cestodes. Works by increasing Ca2+ and Na+ influx leading to instant contraction of muscles. Also causes almost immediate vacuolation of the tegument. Only drug with high efficacy against Echinococcus. Cornerstone of hydatid eradication campaign. Effective against some trematodes (Schistoma spp. not Fasciola) |
|
|
Describe the general mode of action and pharmacokinetics of nitroxynil, oxyclozanide, rafoxanide and closantel |
Nitroxynil Is a substituted phenol. The rest are salicylanilides. Both act by binding to plasma proteins and uncoupling oxidative phosphorylation and interfere with mitochondrial metabolism. Generally only available to blood feeding parasites. |
|
|
Describe the general mode of action and pharmacokinetics of Triclabendazole |
A benzimidazole. Effective against adult (bile duct) and immature (parenchyma) liver flukes. Works differently to other benzimidazoles as usually these are not effective against trematodes. (Triclabendazole is only effective against Fasciola family) |
|
|
Define Side-resistance |
Nematodes resistant to one chemical are also resistant to chemically related compounds e.g. different BZs
|
|
|
Define cross-resistance |
Nematodes resistance to one drug are also resistant to chemically unrelated drugs e.g. levamisol and morantel (possibly act similarly) |
|
|
Define multiple-resistance |
Nematodes resistant to drugs with different modes of action |
|
|
List and describe the factors that predispose to the development of anthelmintic resistance |
1. Excessive or unnecessary drenching - eggs deposited in winter are less likely to develop. Drench frequency needs to be considered in respect to refugia population. 2. Underdosing - possibly facilitates survival of partially resistant worms. Influencced by relative recessiveness/dominance of the trait which will determine if will express any resistance. 3. Accidental introduction of animals infected with resistant worms - store lambs etc 4. Inappropriate drenching - need to drench and move and drench within prepatent period. |
|
|
Discuss the concept of refugia |
Refugia refers to the parasites on a farm that are able to cycle through livestock without being exposed to anthelmintics - no selection pressure for resistance in this population. Act as repository of susceptible parasites that are able to dilute out the survivors of any anthelmintics - don't want resistant survivors to mate with other resistant survivors. Want them to be heterozygotes. |
|
|
Describe ways to reduce the risk of development of resistance and how to manage resistance after is has developed. |
1. Develop a Worm Control Plan - Avoid excessive or unnecessary drenching. Ideally animals should not be drenched unless there is a definite production benefit. Use grazing management and alternative species should reduce reliance on drenching. 2. Avoid Underdosing - At least recommended dose of drug. Better to overdose. Dose to highest weight not average. 3. Rotate action families annually - will allow less fit survivors to die out and the gene frequency for resistance against previous drench return to pre-use levels. Slow rotation of action families is very important to stop multiple resistance. 4. Use anthelmintic combinations - developed to try and slow down drench resistance. If animals are drenched with 3-in-1 and moved to "clean" pasture this could prove to be very rapid way to generate multiple resistance. 5. Check drench efficacy - do egg counts after drenching within prepatent period. 6. Quarantine drench all bought in stock - before integration into herd - leave them to empty. |
|
|
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 |
d. Orf Virus. All other choices are capable of producing generalised infection.
|
|
|
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 |
a. African Swine Fever Virus. As an arbovirus, African swine fever virus replicates within an invertebrate host (a soft tick).
|
|
|
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 |
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. |
|
|
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. |
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.
|
|
|
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. |
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. |
|
|
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. |
b. Equid herpesvirus type 1. Herpesviruses are very fragile in the environment. All other choices are very resistant. |
|
|
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. |
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. |
|
|
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. |
c. Psitaccine beak and feather disease virus. Both clinical signs are seen in psitaccine beak and feather disease virus.
|
|
|
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 |
b. Adenovirus. egg drop syndrome, an adenovirus which causes birds to produce weak or thin-shelled eggs.
|
|
|
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. |
b. Infection is associated with intracytoplasmic inclusion body formation. Adenoviruses produce intranuclear inclusion bodies. |
|
|
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. a. The test is likely to have detected the vaccine strain - nothing to worry about. Since Lucky's clinical signs are not alarming, you advise the owners to keep an eye on him at home. b. 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. c. The test is likely to have detected the vaccine strain. However, just to be safe, it would be best to give Lucky his second dose of parvoviral vaccine before sending him home. d. It is most likely to be a false-positive result, as parvo would be a very unlikely diagnosis for Lucky, considering the fact that he was vaccinated 3 weeks ago. e. Lucky is most likely in the early stages of parvovirus infection, since one vaccination would not be fully protective. However, because of his vaccination history, Lucky is unlikely to develop severe disease, and can probably be cared for at home. |
b. 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. |
|
|
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. |
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). |
|
|
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. d. Dog 2 has the highest level of anti-CPV-2 antibody, indicating that this dog is well protected against CPV-2 disease. e. The range of HI titres is to be expected, as not all dogs will respond equally well to the same vaccination. |
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.
|
|
|
Parvoviruses: a. Can be easily 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. |
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. |
|
|
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. e. It would be best to vaccinate the queen with a live attenuated vaccine, as this type of vaccine provides best immunity and the attenuated virus is very unlikely to cross the placenta. |
c. It would be best to vaccinate the queen with a killed vaccine, as such vaccines do not have a potential of crossing the plaenta 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. |
|
|
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 |
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. |
|
|
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. |
e. High titre, low passage vaccines 'break through' maternally transferred passive immunity eariler 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. |
|
|
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. |
b. Direct and light microscopic inspection of faeces. The virus won't be visible using a conventional microscope but intranuclear inclusion bodies may be visible in a blood smear. |
|
|
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. |
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. |
|
|
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. |
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. |
|
|
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. |
e. Certain genetic strains of PCV-2 are known to be more likely to cause PMWS. All other choices are true. |
|
|
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. |
e. Rapidly cleared from the body after infection resolves. All other choices are true. |
|
|
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. |
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. |
|
|
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. e. Puppy C. It has the levels of antibody high enough to ensure anamnestic response, but not high enough to interfere with vaccination. |
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. |
|
|
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. |
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. |
|
|
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. |
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. |
|
|
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. |
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. |
|
|
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. |
d. In both causes 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). |
|
|
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. 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. |
a. In both cases, a low pathogenicity 'precursor' virus persists in the host 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). |
|
|
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. |
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. |
|
|
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 to 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. |
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). |
|
|
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. |
e. Feline infectius peritonitis virus FIP does not affect horses and even if it did, FIP targets macrophages rather than neural cells. |
|
|
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. |
b. The available vaccine has shown good level of protection against FIP in adult immunocompetent cats.
|
|
|
Define immunity. |
State or qualitu of being resistant to infection either by: - inherent trait (innate immunity) - previous exposure (adaptive immunity)
|
|
|
List the anatomical and physiological barriers that act as a form of innate (non-specific) immunity. |
- Skin - enzymes (some have retarding effects) - other bacteria which are beneficial which outcompete pathogenic barriers. - body temp (fries 'em) - lysozymes in tears - antibacterial peptides (defensins) - Complement system |
|
|
List the phagocytic barriers to infection |
Neutrophils Macrophages |
|
|
Describe the basic action of a chemtactic molecule in inflammation |
Neutrophil emigration (migrate from blood) |
|
|
What does DAMPs stand for? |
Damage associated phagocytic barriers. |
|
|
Vasoactive and chemotatic factors react with the endothelial cells of blood vessels to cause changes in __________. |
permeability, diameter - tight junctions become less tight. Allows neutrophils to squeeze through these tight junctions toward location of microorganisms in the tissue. |
|
|
What is the role of expressing selectins on the endothelial cells of blood vessels? |
Causes neutrophils to slow down |
|
|
What is the role (basically) of integrins on the surface of the neutrophil |
Cause neutrophils to stop at region of selectin and bind to the endothelial cells |
|
|
List the systemic responses to inflammation |
- Macrophages, mast cells, dendritic cells and epithelial cells lining the resp and GIT tract secrete: - cytokines that cause fever and behavioural changes (nausea) (Excess cytokine secretion (cytokine storm) can be lethal. |
|
|
What does PAMPs stand for? |
Pathogen associated molecular patterns |
|
|
In simple terms, describe the role of DAMPs |
Alarm signals from dead or dying/damaged cells |
|
|
What does PRR stand for? And what is it's role? |
Pattern Recognition Receptors and they recognize signals from DAMPs
|
|
|
True or false: Clinical disease of a parasite infected animal can be the result of the way the host responds. |
True |
|
|
List the conditions that need to be taken into account when considering how animals become parasitised. |
- # and density of permissive and non-permissive definitive hosts. - # and density of permissive intermediate hosts. - Environmental factors - development and survival of infective stages. - Parasite factors - fecundity and longevity, pathogenicity - Management factors |
|
|
List the likely effect(s) of a parasite infecting a non-permissive host. |
- Fail to establish patency/are killed. - Fail to esblish patency/hide in the tissues (paratenic host) - establish only in small numbers - generally fail to affect host numbers
|
|
|
What animal, in terms of age and immune status is most permissive to parasite infection? |
Young, immunologically naive definitive hosts |
|
|
Why is it that very young animals are often protected from parasite infection? |
They are seldom eating grass and are consuming mainly their mothers milk. |
|
|
True or False: For some parasites, older animals can be harder to infect even if it is the first time |
True. e.g. Ascarid nematode Toxocara canis - hepatic tracheal migration in 3 week old pup not not 3 month old dogs.
|
|
|
True or false: Abomasal parasites and parasites of the small intestine induce faster and better immunological responses than parasites of the large intestine. |
True. |
|
|
Match the words to their correct definition. Majority of animals have _______ proportion of overall population of worms. Minority have _______ proportion of worm burden. (Majority, tiny) |
Tiny; Majority. Not a bell curve - overdispersed - partly due to host genetics. |
|
|
Match the strongylid group to the colloquial name/ description. 1. Trichostrongyloidea 2. Strongyloidea 3. Ancylostomatoidea 4. Metastrongyloidea
A. The hookworms B. Stouter, big mouthed worms C. The Lung Worms D. The hairworms |
1. D; 2. B; 3. A; 4. C |
|
|
List 3 things required for a nematode egg or larvae to develop |
- O2 - Moisture - sufficient warmth/optimal temp |
|
|
What is the minimum temp below which there is no activity or development for a nematode egg or larvae? |
5-10 degrees centigrade |
|
|
Rank the different types of faeces by which is least to most likely to cause desiccation of a nematode larvae/egg |
Dung pats > (loose) sheep pellets > diarrhoeic faeces |
|
|
Describe an immunogen |
An antigen that elicits a stronger immune response |
|
|
Describe an epitope
|
The part of an antigen that elicits an immune response (the recognizable part)
|
|
|
List 3 types of 'professional' APCs (antigen presenting cells) |
- Macrophages - dendritic cells - B cells |
|
|
In what kind of tissue is an antigen presented (by an MHC 2 molecules) to a helper cell? |
Secondary lymphoid tissue |
|
|
Describe the role of primary lymphoid organs |
regulate the production and differentiation of lymphocytes |
|
|
List some different examples of primary lymphoid tissue |
Thymus Bursa (birds only) Peyers Patches (ruminants) Bone marrow |
|
|
Describe the role or sedondary lymphoid tissue |
Where antigen presenting and processing occurs and lymphocytes respond to antigen |
|
|
List some different examples of secondary lymphoid tissues |
Tonsils Spleen Lymph nodes Peyers patches Bone marrow |
|
|
List some differences between B and T cells |
B cells: Have BCR, consist of antibody molecules (IgM and IgD), which can bind to free antigens and also signal transduction molecules Igalpha and Igbeta. T cells: Have TCR, cant bind free antigens, not an IgM molecule, has glycoproteins called CD3 (CD4 = helper cell, CD8 = cytotoxic) |
|
|
What is the difference between T helper 1 and T helper 2 cells |
The cytokines they produce |
|
|
What do T helper 1 cells produce? |
Help cytotoxic T cells, IFNgamma and IL2 cytokine production |
|
|
What do T helper 2 cells produce? |
Produce B cell growth factor (help with antibody/B cell production)
|
|
|
How many signals does a T helper cell require to become activated? |
At least 2 - one provided by binding of TCR to MHC II and other by cytokines produced by APCs - provide cell mediated immunity |
|
|
By what kind of cell must an antigen be processed in order to be involved in the activation of a cytotoxic T cell? |
Dendritic cell |
|
|
How many signals does a cytotoxic T cell require to become activated? |
3. cytokines from dendritic cell, TCR binding complex and IL2 and interferon gamma (IFgamma) complex produced by activated T helper cells
|
|
|
True or false: Eggs from older, more immune sheep are less likely to develop successfully to [L3] |
True |
|
|
What does a larvae need to migrate from faeces? |
Moisture film - to survive dessication |
|
|
True or false: [L3] larvae rely on stored metabolites to survive as they can't eat, and they use them up more quickly at higher temperature (move more) and so their life span decreases |
True. |
|
|
How do ice crystals kill nematodes? |
The ice crystals stab into the cells and rupture membranes. |
|
|
After oral infection many gastrointestinal nematodes migrate into the tissues of the host. True or false. |
False. Many do NOT. Most species burrow into the glands in GIT (occasionally beyond into the lamina propria). |
|
|
How many days would and L3 usually moult to an L4 after infection |
usually 2-3 days post infection |
|
|
Define hypobisis |
Arrested development |
|
|
List egg infective nematodes |
Strongylida - Trichostrongyloidea - Strongyloidea - Ancylostomatoidea - Metastrongyloidea Ascaridida Rhabditida Oxyurida Spirurida Enoplida |
|
|
True or false: Any B cell has only one binding capability |
True |
|
|
IgG are a model for other immunoglobulins. When digested they are split into 3 equal sized fragments which consist of... |
2 Fab and 1 Fc |
|
|
Fc portion of IgG molecule consists of C terminal half of two heavy chains linked by dishulphide bonds and has antigen binding capacity. It can also bind to the Fc receptor on various lymphocytes. True or false. |
False. Fc portion has no antigen binding capacity |
|
|
Describe opsonization |
when a pathogen is marked for ingestion and destruction by a phagocyte |
|
|
Which immunoglobulin is found in the second highest concentration in mammalian serum? |
IgM |
|
|
What is the binding capacity usually of a IgM? |
Despite being a pentamer and having each subunit equipped with 2 antigen binding sites the total binding capacity is usually 5 due to steric hindrance. |
|
|
True or false: IgM is produced in primary immune response |
True |
|
|
List some common characteristics of IgM |
-Ig expressed when you have a response to something for the first time (vax of infx) - major Ig (with IgD) expressed on surface of B cells - most efficient complement fixing antibody. Single molecule bound to antigen can initiate complement cascade. - More efficient that IgG at opsonization and neutralisation of viruses and agglutination. -Confined to blood stream due to large size, probably not involved majorly in protection in tissue fluids or body secretions. |
|
|
Which animals are known to have no IgD? |
Cats and rabbits |
|
|
What is the suggested function of IgD? |
Essentially a B cell receptor. Thought that it may bind to basophils and stimulate cytokine release to cause B cell production |
|
|
Which Ig has the shortest half life? |
IgE |
|
|
What is the function of IgE? |
Mediation of type 1 hypersensitivity reactions. Fc region binds strongly to receptor on mast ceclls and basophils and, together with antigen, mediates release of inflammatory agents from these cells. - granules release bioactive molecules which can increase vessel permeability and other effects. |
|
|
Describe the role of IgE in parasite infections. |
IgE can bind to mast cells and worm antigens and cause mast cell degranulation and possibly inflammation in an attempt to dislodge the worm. |
|
|
Where is IgA synthesised? |
In plasma cells |
|
|
Where can IgA be found? |
In external secrections of non-ruminants |
|
|
What is the function of IgA |
Important in protecting intestinal, resp, UG tracts, the mammary glands and eyes against microbial invasion |
|
|
What effect does IgA binding to the secretory component have on its effectiveness? |
Enhances its effectiveness as mucosal immunoglobulin |
|
|
Where is IgA often found? |
In lumen of gut - protecting gut surface - prevents bacteria binding to gut wall |
|
|
True or false: IgA stimulates the complement cascade. |
False. You do not want inflammation in the gut |
|
|
Which Ig is mainly produced during primary immune response, when an animal is first exposed to an immunogen? |
IgM. Relatively short lived antoibody response. |
|
|
Describe the lag phase of the immune response kinetics. |
Time between contact with immunogen and detection of antibodies in the circulation (Tand B cell activation occuring). |
|
|
Which Ig is most commonly found in the scondary or anamestic response to an immunogen (e.g. repeat infection or after a booster vax) |
IgG |
|
|
At what terminal of the polypeptide chain of an immunoglobulin is the Variable (V) portion found? |
Amino Acid Terminal |
|
|
At what terminal of the polypeptide chain of an immunoglobulin is the constant (C) portion found? |
Carboxyl Terminal |
|
|
How many different CH (heavy chain constant domains) are there? |
4 (CH1-4) |
|
|
How many kinds of light chains are there? |
2. Kappa and Lambda |
|
|
True or false: A given immunoglobulin molecule always contains identical Kappa or Lambda chains and never a mixture of the two. |
True. |
|
|
True or false: H chains determine the class of the immunoglobulin |
True |
|
|
A γ heavy chain will be found in which Immunoglobulin class? |
IgG |
|
|
A µ heavy chain will be found in which Immunoglobulin class? |
IgM |
|
|
An α heavy chain will be found in which immunoglobulin class? |
IgA |
|
|
An ε heavy chain will be found in which immunoglobulin class? |
IgE |
|
|
A δ heavy chain will be found in which immunoglobulin class? |
IgD |
|
|
why can't non-lymphocyte cells express the genes for making immunoglobulins? |
They do not have the molecular machinery to perform the rearrangement and splicing of the RNA transcripts. |
|
|
Fill in the blank: The κ light chain family consists of only 1 Cκ Exon, however the sequence encoding any given V domain is contained on ___ separate gene segments called the ___ and ___ segments. |
2; Vκ; Jκ |
|
|
What is the purpose of a Jκ segment in a κlight chain? |
It is known as the joining segment and it joins to the Vκ segment. Which is then transcribed together with the Cκ exon. |
|
|
What happens to the Vκ/Jκ exon after it has been transcribed together with the Cκ exon? |
The transcript is spliced to form the mature κ mRNA |
|
|
What is the consquence of only having only 1 Cκ exon in the κ L chain family? |
All κ proteins have identical C region sequences. Shuffling of the Vκ and Jκ segments is the most important source of diversity |
|
|
What is the main difference between the κ L chain family and the λ L chain family? |
Between 6-9 slightly different copies of Cλ exist, each in close proximity to Jλ segment. Any of these Cλ alternatives may fuse with Jλ segments and the resulting Vλ/Jλ exon can then be transcribed with the adjacent Cλ exon. |
|
|
Which enzyme joins the ends of V and J segments? |
DNA dependent kinase. Animals without this can't make B or T cell receptors. Initially protected by mothers immunoglobulins from colostrum, but after these start to decline they start to get sick and die. |
|
|
How many H chain isotypes exist? |
9, arrayed in a tandem along the chromosome in the following order: Cµ, Cδ, Cγ3, Cγ1, Cα1, Cγ2, Cγ4, Cε, Cα2
|
|
|
How many VH and JH segments exist? |
Several hundred VH and 6 JH |
|
|
What is the DH segment of a H chain |
Diversity segment. Lies between JH and VH. |
|
|
What is different about L chain assembly and H chain assembly? |
With H chain, one DH and JH segment are fused (V/D/J joining). No DH in L chain, just V/J joining |
|
|
What is the significance of the DH segment in the H chain? |
Greatly increases amount of H chain diversity. |
|
|
What kind of C segment can the primary transcript of an H chain have? |
Cµ or Cδ as they are both in close proximity to each other and to the VDJ segment. -can be trasncribed all together |
|
|
How do different C isotypes get expressed in an H chain? |
Specific DNA deletion must occur which brings one of the other C exons adjacent to the original VDJ exon. B cell changes from producing IgM to other classes of Ig |
|
|
Why does the local environment in Peyers Patches of the gut appear to favour switching C isotypes to Cα1? |
This results in the production of IgA |
|
|
True or false: Cδ and Cµ are often transcribed together due to their close proximity. (H chain assembly) |
True. The consquence of this is B cells being able to splice and yield either δ or µ mRNA so the cell can produce IgM and IgD antibodies of the same specificity simultaneously. |
|
|
How many L chain possibilities are there given random joining? |
80 x 5 = 400 possibilities |
|
|
How many H chain possibilities are there given random joining? |
300 x 5 x 2 = 3000 possibilities |
|
|
When a light chain is paired with a H chain to create an antigen binding site, how many possible combinations are there? |
400 x 3000 = 1.2 million |
|
|
How is additional diversity achieved in antigen binding sites in relation to H and L chains? |
Base deletions and insertions between the splice sites (resulting in frame shift) and by somatic mutation. |
|
|
Describe the function/role of an MHC (Major Histocompatibility Complex) |
MHC molecules are cell surface receptors that determine which antigens can be presented to the immune system. |
|
|
True or false: MHC molecules are highly polymorphic |
True |
|
|
How many MHC class I molecules can we express? |
6 different molecules |
|
|
True or false: MHC molecules are very specific and will only present very specific molecules on its surface. |
False. MHC molecules are very promiscuous and will present lots of different molecules on its surface. |
|
|
Why do we only have 6 MHC molecules instead of more? |
6 is optimal number to balance between susceptibility to infection and the need to avoid autoimmune disease. |
|
|
How many MHC receptors can be present on a cell at one time? |
50-100 thousand |
|
|
Where are MHC Class I molecules found? |
On all nucleated cells of the body ~ APC, epithelial cells, T cells etc... |
|
|
Where are MHC Class II molecules found? |
On all professional APCs ~ dendritic cells, macrophages and B cell. They present to T helper cells. |
|
|
How many amino acids can fit into the peptide binding groove of a Class I HLA molecule? |
9 Amino Acids. |
|
|
Fill in the blanks: Each HLA-A,-B,-C molecule consists of a polymorphic transmembrane _____ non covalently associated with a ________________. |
α-chain; β2 microglobulin chain (invariant) |
|
|
How many extracellular domains does a Class I HLA molecule have and what are they called? |
3. α1, α2, α3.... Class I HLA molecule essentially made up of an α chain. |
|
|
Between which domains of the Class I HLA molecule does the Ab bind? |
between α1 and α2 domains. |
|
|
What is an important difference between MHC receptors and the highly specific immunoglobulin antigen binding sites? |
MHC receptors are loosely specific and can potentially bind to a very large number of different peptides (some better than others). However the MHC receptor of a given individual cannot bind to every peptide against which immunity is desired. |
|
|
Describe the function of a Class I HLA molecule |
Endogenous proteins (e.g. from virus) are degraded in peptides (~8-15aa) in the proteosome, transported to the ER and further degraded by ERAAP enzyme and 9 aa peptides are loaded onto class I molecules. The class I/peptide complex is then transported to the cell surface and presented to a cytotoxic T cell. |
|
|
What does ERAAP stand for? |
Endoplasmic reticulum aminopeptidase associated with protein processing. |
|
|
What sized AA peptide can fit within and extend beyond the peptide binding groove of a Class II HLA molecule? |
12-25aa peptide |
|
|
What kind of glycoprotein chains does a Class II HLA molecule consist of? |
an α and a β glycoprotein chain in noncovalent association |
|
|
Which area of Class II HLA molecule chain forms the antigen binding site? |
α1 and β1 - it is also this region where variability can be found. |
|
|
When a peptide is associated with the antigen binding groove of a class II HLA molecule it makes up the ligand recognized by the receptor on ______ (what type of...) Helper T cells. |
CD4. For Class I HLA is it CD8 (associated with cytotoxic T cells) |
|
|
How many different MHC II molecules can you have? |
12 due to having DR, DP and DQ molecules in Class II HLA |
|
|
Which cells express the most MHC II molecules? |
Dendritic cells. Followed by macrophages but they are quite slow to express. |
|
|
Describe the function of Class II HLA molecules. |
Exogenous antigen is ingested (by macrophage, dendritic cell or B cell), broken down into peptides by phagolysosome, which fuses with ER. Peptides bind to MHC II molecules and are transported to the cell surface and presented to Helper T cells (TH1 and TH2) |
|
|
what is the role of MHC II molecules on the surface of APCs? |
They act as peptide receptors and as a result they regulate the recognition of antigens by helper T cells |
|
|
Describe the difference between the antigens of an MHC I molecule being derived endogenously whereas the antigens presented to MHC II molecules come exogenously. |
MHC I antigens are broken down in the cytoplasm. MHC II antigens are broken down in the phagolysosome. |
|
|
What are the two different types of T cell receptors of a T helper cell? |
δ and γ are one. The other consists of 2 different peptides α and β. |
|
|
True or false: Any one T cell can express both α/β receptors or the γ/δ receptors at any one time. |
False. Any one T cell can express either but never both together. |
|
|
Finish the sentence: TCR are always associated with a set of invariant glycoproteins collectively called ____. They are thought to be involved with regulation of T cell activation following occupancy of the TCR by an antigen/MHC complex. |
CD3 |
|
|
True or false: Certain MHC alleles can be associated with an increased risk of certain diseases. |
True, this is known as relative risk. |
|
|
True or false: T cell receptors are highly specific for certain antigens. |
True. |
|
|
T cell receptor is made up of _____ chain (similar to L chain of Ig) which is put together by fusing __ and __ segments. The _____ chain contains a _____ segment. |
α; V; J; β; V/D/J. The VDJ segments are put together in the thymus where the T cells mature. |
|
|
True or false: T cells can see free antigens. |
False. Only B cells can see free antigens |
|
|
What happens to T cells whose TCR allows them to reconise 'self' antigens? |
Destroyed during development in thymus - autoimmune! |
|
|
Explain how a toxin from an exogenous source can activate T cells and cause problems. |
Only T cells that recognise the presenting antigen will be activated. Some toxins can activate many different T cells. Up to ~20% T cell activation. |
|
|
Describe "host resistance" |
Immunological resistance to parasites. Not to be confused to "anthelmintic resistance" |
|
|
True or false: host resistance in terms of parasites if often considered 'sterile' |
False, rarely a sterile response. "Immunity" implies total protection - rarely achieved against parasites. |
|
|
Which parasite antigens can really only stimulate a useful immune response? |
Excretions and secretions (ES) from the parasite |
|
|
True or false: Hosts can mount an immune response to both somatic (structural components) and ES parasite antigens but only ES antigens will elicit protective immunity. |
True. |
|
|
What are the main targets for TH1 cells in terms of parasites? |
Mainly intracellular targets such as malaria |
|
|
What are the main targets for TH2 cells in terms of parasites? |
Mainly extracellular parasites such as helminthes. |
|
|
Explain why the TH1 and TH2 cells inhibiting each others actions can be problematic. |
Issues with multiple parasite burdens - GI worm vs. Malaria - cant fight both |
|
|
What is an increased number of eosinophils commonly associated with? |
Parasites. They contain a number of inflammatory mediators that are potentially toxic to nematodes. |
|
|
State some conditions for eosinophils to be toxic to nematodes. |
- must degranulate onto the surface of a nematode. - needs to be in direct contact with the parasite. - mainly works against helminthes in tissue phase |
|
|
True or false: If eosinophil levels in the blood are not elevated then there eosinophil levels are normal. |
False... Not necessarily, they are in transit in the blood so they may be at required site instead. |
|
|
An increased number of mast cells is commonly associated with .... |
GIT nematode |
|
|
What is significant about seeing globule leukocytes between the epithelial cells? |
They are a marker of gut parasites and chronic parasitism. |
|
|
True or false: Animals take much longer to develop immunity to parasites. |
True |
|
|
How long after ingestion as a lamb will it be before a lamb shows/develops some immunity to worms? |
6-10 months |
|
|
How long after ingestion as a lamb will it be before the lambs immunity against a worm is fully mature? |
18 months |
|
|
Describe premunity |
Premunity describes how resitance only lasts as long as a low level of infection persists. This means the animal has made it trough the acute stage of infection and will then resist infection as long as it has a low level of infection. |
|
|
Describe different ways in which immunity to parasite infection can be expressed |
- ↓ egg production - interferes with interpretation of faecal egg count on older animals - ↓ viability of eggs - stunting of nematodes - morphological changes in nematodes (e.g. Haemonchus may lose its vulval flap in immune animals) - rejection of developing larvae - expulsion of adults |
|
|
What kind of vaccines are available for parasites? |
Somatic antigens generally dont work so only attenuated live parasite vaccines are available. - X-irradiated or γ-irradiated |
|
|
Describe how novel antigens work against Haemonchus contortus |
they target intestinal epithelial cells. As blood feeders, Haemonchus ingest the blood with antibody and the antibody coats the intestinal cells interfering with its funciton. |
|
|
How long for onset of Trichostronyloid immune response? |
4-6 months and 18 months to be fully mature
|
|
|
How long for onset of Ascaridoid immune reponse? |
Very rapid. Only a few days or weeks. Limits how many larvae get to complete migration through liver to the lungs. |
|
|
Are paramyxoviruses enveloped or non-enveloped? |
Enveloped. |
|
|
How are paramyxoviruses usually transmitted? |
By aersosol |
|
|
Surface glycoproteins determine which kind of paramyxovirus the virus will be. Match the types of glycoprotein to the type of virus it is associated with: 1. HN 2. H 3. G
A. Morbilli B. Pneumo C. Paramyxo |
1 = c; 2 = a; 3 =b |
|
|
What is the nucleocapsid of a paramyxovirus usually described as being? |
'herring bone' or zipper-like |
|
|
What is the action of the fusion protein (F) of paramyxoviruses? |
Causes fusion of virus-infected cells with uninfected cells (syncytia) |
|
|
What two diseases is Bovine Parainfluenza 3 associated with? |
Shipping fever and calf pneumonia |
|
|
Where does Bovine Parainfluenza 3 replicate? |
In the upper respiratory tract |
|
|
True or false: Bovine Parainfluenza 3 usually causes mild or subclinical disease. |
True. Recovery usually after a few days. Can be complicated by 2° bacterial infections. |
|
|
List some conditions known to make Bovine Parainfluenza 3 worse. |
- Stress - Crowding - concurrent disease
All these determine the severity of the disease |
|
|
True or false: Bovine Parainfluenza 3 is difficult to diagnose. |
True. It is often subclinical, and a variety of other agents can cause shipping fever also. |
|
|
From what genus is New Castle Disease Virus? |
Avulavirus |
|
|
What is a significant difference between New Castle Disease virus and other paramyxoviruses? |
It is relatively resistant in the environment in comparison. |
|
|
True or false: New Castle Disease Virus has one serotype, but a number of different pathotype variations in virulence and tissue tropism. |
True. |
|
|
Match the New Castle Disease pathotypes with their correct virulence: 1. Lentogenic 2. Mesogenic 3. Velogenic
A. Avirulent (Present in NZ) B. Mortaility up to 100% C. Mortality up to 25% |
1. = A; 2. = C; 3. = B |
|
|
How long will a bird infected with New Castle Disease Virus shed the disease for? |
At least 4 weeks |
|
|
True or false: Psittacine birds can be persistently infected with New Castle Disease without any clinical signs |
True |
|
|
List the clinical signs of New Castle Disease Virus |
- Respiratory signs - Neurological signs - Digestive signs (diarrhoea) - Partial or complete egg drops
|
|
|
From which disease is New Castle Disease clinically indistinguishable |
Highly pathogenic Avian Influenza |
|
|
List 6 examples of Morbilliviruses |
- Canine distemper virus - Rinderpest virus - Reste-des-petits ruminants virus - Cetacean morbillirvirus - Phocine distemper virus - Measles (human) |
|
|
Which tissues do morbilliviruses target? |
Epithelial, neural and lymphoid tissues |
|
|
True or false: Morbilliviruses are highly contagious and hardy in the environment |
False. While they are highly contagious, they are very fragile in the environment |
|
|
What type of immune response/immunity is important in the recovery of a morbillivirus? |
Cell-mediated immunity |
|
|
True or false: Canine distemper virus is an important cause of mortality in wildlife e.g. African lions |
True |
|
|
How many days post-infection will an animal start to shed Canine distemper virus? |
5dpi and will persist for weeks
|
|
|
How does canine distemper present in: - Peracute form - Acute form - Subacute form
|
- peracute = sudden death - acute - Incubation for 3-5 days; biphasic increase in temp (up to 41°C); severe leucopenia, anorexia and conjuncitivitis; predominant resp (bronchopneumonia) or GI (vomiting/diarrhoea) signs; some CNS signs can occur. - subacute (neurlogical) - can follow acute disease; encephalitis with convulsions and seizures; Survivors may have permanent nervous 'ticks' or involuntary leg movements. |
|
|
Describe Old Dog Encephalitis |
Late onset canine distemper virus. Slow progessive loss of neurological function.
|
|
|
True or false: Hard-pad disease is a late form of canine distemper virus. |
True. Can also be associated with neurological disease and even end in death |
|
|
True or false: Rinderpest virus has been successfully eradicated. |
True. |
|
|
Describe the clinical signs of Rinderpest virus |
- Ocular and nasal discharge - Erosions in the mouth - "3D's" ~ diarrhoea, discharge and death |
|
|
Give two examples of emerging paramyxoviruses. |
- Hendravirus ~ zoonotic and deadly; from horses - Nipavirus ~ Malaysia; possibly from bats |
