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200 Cards in this Set

  • Front
  • Back
What are the DNA viruses?
Circoviridae
Parvoviridae
Hepadnaviridae
Papillomaviridae
Polyomaviridae
Adenoviridae
Herpesviridae
Asfarviridae
Iridoviridae
Poxviridae
What are the single stranded DNA viruses?
Circoviridae (+)
Parvoviridae (-)
What are the double stranded DNA viruses?
Hepadnaviridae
Papillomaviridae
Polyomaviridae
Adenoviridae
Herpesviridae
Asfarviridae
Iridoviridae
Poxviridae
What is the parvovirus?
ssDNA virus (-)
red inclusion bodies
replicates in nucleus
causes hemorrhagic enteritis, affects fast growing cells such as bone marrow
resistant in environment
ex: parvo in dogs
What is the papillomavirus?
dsDNA virus
no inclusion bodies produced
replicates in nucleus
encode proteins that promote growth
stable in environment
ex: warts, cancer of the cervix pharynx and anus
What is adenovirus?
dsDNA virus
blue inclusion bodies
replicate in nucleus
have pentons
produce Ab to epitopes
resistant in environment
ex: kennel cough
What is asfarvirus?
dsDNA virus
red inclusion bodies
replicates in the cell cytoplasm and in soft ticks
Ex) african swine fever
What is herpesvirus?
dsDNA virus
red inclusion bodies
syncytium and fuse with neighboring cells
very fragile in environment
ex: feline rhinotracheitis - corneal ulcer
*herpes virus mimics thymine
What is poxvirus?
dsDNA virus (largest)
red inclusion bodies
multiply in cytoplasm
manifests in skin first
small pox, cow pox
survive many years
What is Hepadavirus?
partially ds and partially ss DNA virus
replicates in nucleus of hepatocytes
replication involves reverse transcriptase
ex: hepatocytes hep B
What is polyomavirus?
associated with inapparent infections
highly host specific
replicate in the nucleus
causes french molt and budgerigar fledgling disease in birds
What is circovirus?
ssDNA virus (smallest)
blue inclusion bodies produced
replicates in the nucleus
large inclusions
stable in environment
ex) chicken anemia
What DNA viruses show blue inclusion bodies?
adenovirus
circovirus
What DNA viruses replicate in the cytoplasm?
Asfarvirus
Poxvirus
What DNA viruses have red inclusion bodies?
Parvovirus
Asfavirus
herpesvirus
poxvirus
What DNA viruses have no inclusion bodies?
papillomavirus
hepadnavirus
What is a virus?
"Fluid poison"
used to describe infections agents that passed through bacteriologic filters
What is a host range for viruses?
range of animal species and tissue cells that the virus can infect - broad or limited
What is a structural unit?
protein subunit which may be assembled into capsomers - can have one or more subunits
What is a capsomere?
morphological subunit from which the virus capsid is built
What is a capsid?
protein shell or coat that encloses the nucleic acid genome
What is a nucleocapsid?
the capsid together with enclosed nucleic acid
What is a virion?
the complete infective virus
What is an incomplete virion?
viron without the nucleic acid
What is a defective virus?
a virus that can not replicate because it lacks full complement of viral genes
replication occurs in mixed infections with helper virus

example: pseudotype
What is a pseudotype?
during replication in co-infected cells the genome of one virus may become encapsulated in the heterologous protein coat encoded by a second virus
What is a pseudovirion?
during viral replication the capsid sometimes encloses host nucleic acid and therefore does not replicate
What is an episome?
Autonomouse extra-chromosomal genetic element that can be integrated with chromosomal DNA
What is a provirus?
viral DNA that is integrated into a host cell chromosome in a latent state and must be activated before it is transcribed
What are the architectures of capsids?
Icosahedron = cubic
Helical- usually encapsulated
Complex ex poxvirus
What are the functions of capsids?
structural symmetry
protection of nucleic acid
facilitates attachement
determines antigentic characteristics
What is a viral envelope?
acquired from cellular membranes
occurs only at sites where virus specific proteins have inserted into host cell
What are enzymes transcribing the viral genome into mRNAs?
DNA dependent RNA polymerase such as pox and asfivirus

RNA dependent RNA polymerase uses (-) sense genome
* host cells lack this enzyme
What are enzymes involved copying virion RNA to DNA?
RNA dependent DNA polymerase (reverse transcriptase) in hepadnavirus and retroviruses
What are enzymes that copy the nucleic acid genome?
DNA dependant DNA polymerase
Stability of viruses: which is more stable?
Naked viruses survive well inside and outside the body
Enveloped viruses are more susceptible to environment factors which include temperature and pH
What are the RNA viruses?
Picornaviridae
Caliciviridae
Togaviridae
Arteriviridae
Flaviviridae
Reoviridae
Birnaviridae
Coronaviridae
Paramyxoviridae
Orthomyxoviridae
Rhabdoviridae
Retroviridae
Bunyaviridae
Bornaviridae
Arenaviridae
What is the picoravirus?
Small stable ssRNA (+) virus
replicates in the cytoplasm
no inclusions
causes foot and mouth, common cold, ulceration, polio and hep A
What is the calicivirus?
ssRNA virus (+) replicates in cytoplasm, no inclusions
causes feline calici virus, ulceration on tongue and hep E, lagovirus (bunnies)
What is the togavirus?
ssRNA virus (+) with an envelope and icosahedral nucleocapsid
replicates in the cytoplasm - budding
causes EEE in horses and Rubella in humans
What is the Arterivius?
ssRNA virus (+) with envelope
replicates in the cytoplasm - budding
likes macrophages and multiplies in blood vessel walls
causes edema, abortion in horses, porcine reproductive and respiratory syndrome
What is the Flavivirus?
ssRNA virus (+) with envelope
replicates in the cytoplasm
labile in environment
causes yellow fever, bovine viral diarrhea
What is the reovirus?
repiratory enteric orphan
dsRNA virus w/ 2-3 capsids
replicates in cytoplasm
produces red inclusions (perinucleur and intracytoplasmic)
stable in environment
causes blue tongue in sheep, causes diarrhea, african horse sickness
What is the Birnavirus?
dsRNA virus
replicates in cytoplasm
stable in environment
causes infections bursal disease (decrease B lymphocytes)
What is the coronavirus?
enveloped ssRNA virus (+)
replicates in the cytoplasm
budding in ER and golgi
narrow host range
moderately resistant
no inclusions
causes FIP - immune complex hypersensitivity
What is the Paramyxovirus?
ssRNA (-) virus
large helical nucleocapsid with envelope
red inclusions in cytoplasm
syncytium
labile in environment
causes canine distemper and human measles
What is the orthomyxovirus?
ssRNA virus (-)
replicates in cytoplams and nucleus - budding
labile in environment
causes influenza A, B and C
segmented genome - multipartite
What is the rhabdovirus?
ss RNA virus (-)
replicates in the cytoplasm
produces inclusions (negri bodies)
broad host range
rapidly inactivated by UV light
Causes rabies
What is the retrovirus?
ssRNA virus (+)
contains reverse transcriptase = produce DNA copy of RNA genome
provirus - budding in plasma membrane
all oncogenic RNA viruses are in this family
causes HIV, FIV, equine infectious anemia
What is the Bunyavirus?
ssRNA virus (-)
replicates in cytoplasm
transmitted by arthropods and rodents
labile in environment
causes huntavirus
What is the bornavirus?
ssRNA virus (-)
spherical and enveloped
replicates in nucleus and produces large inclusions
has affinity for nervous tissue
labile in environment
causes meningeoencephalomyelitis
What are the (-) RNA viruses?
Orthmyxooviridae
Paramyxoviridae
Rhabdoviridae
Bunyaviridae
Bornaviridae
Arenaviridae
What is the arenavirus?
ssRNA virus (-)
replicates in the cytoplasm
budding in plasma membrane
causes chronic infections
hemorrhagic fever
What is cell culture?
it involves the growth of dispersed animals cells in vitro or as cells in suspension as a monolayer
What is a primary cell culture?
Tissue taken directly from human or animal cells
cells have same number of chromosomes
detached by trypsin and chelated by EDTA
produces 5-20 subcultures
used for viral vaccines
What is serially propagated cell cultures?
diploid cell line
homogenous population from human embryos or subcultures of a primary culture
produces 100 cultures
used to produce some viral vaccines
What is a continuous (heteroploid) cell line?
cells of a single type that are capable of indefinite propagation in vitro
derived from cancer cells and no longer resemble original cell
prohibited use in vaccine production
How do you prepare a monolayer cell culture?
tissue is minced from tissue
cells are washed, counted and treated with protease at 37C
serum, pH indicators and antimicrobial agents are added
grow until confluent
What is a shell vial cell culture?
A type of rapid cell culture where a glass with a coverslip is used for centrifugation and inoculation of monolayer on a slide to be examined microscopically
What are co-cultivated cells?
cells of different types grown together as a single monolayer
What are embryonated eggs?
developed by goodpasture 1930
contain Ab to a virus not suitable for isolation of viruses
between 5 -13 days old
What are the routes on inoculation of embryonated eggs?
yolk sac
chorioallantoic
amniotic
allantoic
intravenous
How do you inoculate an egg by the yolk sac?
at 5-7 days
22 G 1 1/2 needle
for togavirus and avian enterovirus
How do you inoculate an egg by chorioallantoic site?
9 - 12 days
26 or 28 G needle
used for pox and herpesvirus
How do you inoculate an egg by amniotic site?
7-13 days
26 G needle
influenza (orthomyxovirus)
How do you inoculate an egg by intravenous
10 - 12 days
used for bluetongue virus (reovirus)
What are good incubation conditions for an embryonated egg?
good air circulation
temp of 37C
automatic turning racks
62% humidity
What are signs of viral growth in an embryonated egg?
stunted embryo
lesions in chorioallantoic membrane
urate deposits in mesonephros
hemorrhage and congestion
encephalitis
death of embryo
lesions of extracellular membrane
edema
presence of hemagglutinins
When are lab animals used?
used if infectious agent can not yet be grown in cell culture
used to study path mechanisms and study serology
What do we concentrate and purify viruses?
to study the physiochemical characteristics, infectivity, antigenic properties of a virus
centrifugation with sucrose or cesium chloride
What is a virus titration?
quantitative determination of viral activity, the concentration of virus in the sample which can produce disease, lesions or a recognizable effect in the host
What is a virus titer?
determined by inoculating serial dilutions of viruses into tissue culture, eggs or animals and looking for evidence of virus multiplication
determines dose and virus concentration
What is a quantitative assay?
used to measure exact number of infectious virus particles in a sample (monolayer)
How is a virus titer determined?
number of plaques counted multiplied by the reciprocal of the dilution and by a factor to express in PFU/mL
What is a pock assay?
titration of certain viruses like pox and herpes on chorioallantoic membrane
looks are the number of necrotic areas
What is a transformation assay?
oncogenic viruses transform cells so that they display decreased contact inhibition creating a microtumor
What is a quantal assay?
shows presence or absence of infection. does not measure exact number
What is a permissive cell?
contains the necessary intracellular components needed for virus replication
productive infection
What is a nonpermissive cell?
a cell type that does not allow a complete virus replication cycle
abortive or non productive infection
What is multiplicity of infection (MOI)
number of infections viruses inoculated per cell
~ 5-10 per cell
What is an eclipse period?
time between disappearance of infectious virions (uncoating) and appearance of 1st progeny virions intracellulatly ~2-12 hours
seen in enveloped viruses
What is a latent period?
extracellular virions that are not detectable
What is the viral replication cycle?
1 attachment
2 penetration
3 uncoating
4 translation of early mRNA
5 translation of early proteins
6 replication of viral DNA
7 transcription of late mRNA
8 translation of late proteins
9 assembly of virions
What is adsorbtion?
attachment
binding to receptors on the plasma membrane of a cell
What is a co receptor?
number of viruses, successfully infect a cell requiring a cellular receptor for its co receptor
see in HIV
What is penetration?
engulfment or viral uptake
What is cell mediated endocytosis?
selective binding of ligands to specific cell membrane receptors
What is transcription?
nucleic acid molecule transferred to mRNA
What is capping?
addition of 7 methylguanosine to the 5' terminus by mRNA capping enzyme to stabilize mRNA and decrease degradation. it aligns mRNA on ribosomes during translation
What is the poly A tail?
100-200 adenylate residues to the 3' terminus of RNA by polyadenalate acid polymerase and allows mRNA transport out of the nucleus and bind to ribosomes
What is the splicing of viral pre mRNA
involved deletion of intervening non coding sequences (introns) and the ligation of non noncontinuous sequence (exons) by spliceasomes
What is the cytopathic effect?
visible or morphologic change induced in a host cell by a virus that may result in cell damage or death
What are inclusion bodies?
a morphologic change in cells by some viruses and are recognized by H and E stain or by fluorescence microscopy
What are mechanisms of cell damage in cytocidal viral infections?
inhibition of host cell DNA replication
selective inhibition of cellular mRNA
inhibition of cellular mRNA export
shutdown of host cell
destruction of cell content by own lysosomes
promote cell fusion
altering membrane permeability
change in cell shape
apoptosis
cytolysis by ADCC
What are examples of noncytocidal changes in virus infected cells?
persistant infections like most retroviruses (slow progression over time)
damage to homeostatic functions
What is cell transformation?
The changing of a normal cell into a cancer cell
What are proto-oncogenes?
genes whose protein products function in the signal tranduction pathways that control normal cell growth, division and differentiation
What are cellular oncogenes?
genes whose products can transform normal cells when expressed abnormally or in excess from the corresponding proto-oncogenes
What are tumor suppressor genes?
encode proteins that normally act to inhibit cell proliferation during the G1 phase
What is the Rb protein?
retinoblastoma protein
tumor suppressor protein that is dysfuntional in many cancers
protein inhibits the entry of cells into S phase
What is p53
required for apoptosis induced by DNA damage
What are the stages of the cell cycle and what happens during each stage?
G1 - cell growth
S - DNA replication
G2 - cell growth
M - division
What family of viruses for RNA tumor viruses belong to?
Retroviridae
major causes of lymphoma and leukemia
What are acute transforming viruses?
v-onc+
derived from host cell proto-oncogenes and occasionally the proto-oncogene becomes incorporated in the viral genome (defective)
What are chronic retroviruses?
v-onc-
viruses lack v-onc genes and are weakly oncogenic
cell transformation may result from insertion of retroviral promotor and enhancer elements at sites close to or within proto-oncogenes = enhanced expression of the proto-oncogene
What is a mutation?
a heritable change in the nucleotide sequence of the genome of an organism
What is an escape mutant?
mutants affecting antigenic determinants of virion surface proteins
result in persistent infections due to being able to replicate in the presence of the antibody
What are conditional-lethal mutants?
viruses that can replicate only in certain conditions
Ts mutants = temperature sensitive
What are defective interfering mutants?
a virus that lacks one or more functional genes required for viral replication due to a deletion mutation
What is a dual infection?
2 dissimilar viruses that may replicate within the same cell as efficiently as in single infection
What is a genetic interaction?
interactions involving the genomes of the parental virions
resulting progeny are genetically different from either parent
What is genetic recombination?
the breaking of the nucleic acid strains of one parent and joined to part of the genome of the second parent resulting in stable progeny
What is genetic reassortment?
exchange of complete RNA molecules between genetically related viruses with segmented genomes
What are nongenetic interactions?
products of the genes that interact rather than genomes
progeny are similar to parents
What is phenotypic mixing?
when two closely related viruses infect the same cell, the two progeny genomes may become encapsulated by their own or hybrid capsids
causes of different strains
What is viral interference?
when the multiplication of a superinfecting virus in cell culture or in the host is inhibited because of the presence of an initially infected virus
*basis for controlling outbreaks
What is pathogenicity?
The ability of an organism to cause disease by overcoming the defenses of the host
What is virulence?
the capacity of a microorganism compared to other closely related microbes to produce disease in infected host
What are susceptible cells?
virus infected cells whose infection may not be sufficient to cause clinically demonstrable disease
What are target cells?
virus infected cells whose infection usually contributes to clinically demonstrable disease
What are clinical signs?
and objective evidence or manifestation of an illness
what we see as a clinician
What are clinical symptoms
any subjective evidence of disease
what the patient is feeling based on disease
What are portals of entry for microorganisms?
skin
mucus membranes
respiratory tract
gastrointestinal tract
What are some examples of virus spreading?
locally
subepithelially
by lymphatics
hematogenous
What is viremia?
the presence of infectious virus particles into the bloodstream
What is passive viremia?
direct introduction of viruses into the blood steam
What is active viremia?
invasion of bloodstream by progeny
What is primary viremia?
release of progeny virions into the blood after initial replication at the portal of entry
What is secondary viremia?
delayed appearance of high concentration of infectious virus in the blood as a result of disseminated infections
How are viruses cleared from the blood?
mononuclear phagocytes in the spleen, liver and bone marrow
Ab clearance
complement mediated clearance
What is teratogenesis?
abnormal development or arrest in development of the embryo or fetus which may result in death or malformation
What is inapparent (subclinical) infection?
observed in many viral infection where the individual does not have a noticeable illness
What is immunopathology?
tissue damage mediated by hypersensitivity reactions
What is a persistent infection?
an infection in which the pathogen is not cleared efficiently by the adaptive immune response and persists in the body for long periods or throughout life
What is epidemiology?
the study of the occurrence of disease in a population
What are types of vector transmission?
biological
mechanical
vehicle
What is biological transmission?
part of the life cycle that takes place in a vector
What is mechanical transmission?
arthropod being a passive carrier
What is a vehicle?
food, blood, milk water, drugs
places to pick up pathogens
Hos is case fatality calculated?
number of deaths/number of sick X 100
How is mortality rate calculated?
number of deaths/ total population X 100
What is horizontal transmission?
transmission of infection from individual to a population
What is vertical transmission?
transmission of infection from parent to offspring
What is an iatrogenic infection?
infection transmitted from a health care provider to a patient
What is a nosocomial infection?
hospital or clinic acquired infection
What is herd immunity?
the immune status of a population rather than an animal or individual
What are some agent vectors?
infectivity
virulence
transmission efficiency
exogenous pathogens
endogenous pathogens
What are factor environmental factors that cause disease?
season of the year
overcrowding
environmental contamination
reservoir population
arthropod vectors
What are the stages of disease?
inoculation
prodromal
illness
decline
convalescence
What is Chemotherapy?
the treatment of infectious disease with chemicals or antibiotics that are inhibitory or lethal to the infectious agent
What is selective toxicity?
the property of antimicrobial agent to be toxic for a microbe and nontoxic for the host

paul-ehrlich "father" of modern chemotherapy?
What is a macule?
virus replication in the dermis leads to flat, reddened lesion produced by a lasting local dilation of dermal blood vessels
What is a papule?
a raised macule due to localization edema and cellular infiltrates
What is a vesicle?
virus replication spreads from the dermis to the epidermis resulting in a small circumscribed epidermal elevation that contains a clear fluid
What is a pustule?
A vesicle with copious neutrophil infiltration.
Localized erosion or sloughing of endothelium results in ulceration
What is an arbovirus?
viruses that multiply in a arthropod vector
What is case?
an animal suffering from a clinically diagnosable disease
What is case-fatality rate?
the number of deaths among the clinically ill
What is a carrier?
any animal that sheds an infectious agent without demonstrating clinical signs
What is an incubatory (acute) carrier?
animals that excrete agent during the disease's incubation period
What is a convalescent chronic) carrier?
an animal that sheds the infectious agent when they are recovering from a disease
What is a communicable period?
the time during which the infectious agent may be transferred, directly or indirectly from an infect animal to another
What is a contagious disease?
an infectious disease in which the pathogen may be transmitted from one host to another by direct or indirect contact
What is a dead end host?
one that is not involved in maintaining a virus; host does not transmit an infectious agent to other animals or vectors
What is a disease?
any disturbance of the normal structure or function of any part, organ or system of the body that results in a characteristic set of symptoms and signs
What is an endemic?
the constant or usually expected occurring of a disease with a given geographic location
What is an epidemic?
major increase in disease incidence affecting either a large number of animals or spreading over a large area
What is an exotic?
a disease not known to occur in a particular country or geographic area
What is a field isolate?
a fresh virus isolate from the natural host
What is a fomite?
an inanimate object or other vehicle involved in the transfer of infectious agents from one host to another
What is an incidence?
the number of new cases that occur in a population over a specified period of time
What is an incubation period?
The period of time between an infection and the development of signs and symptoms
What is an infection?
invasion and multiplication of microorganisms in body tissues
What is a pandemic?
a geographically widespread epidemic
What is prevalence?
The number of occurences of diseease (old and new) infection or related attributes (presence of Ab) in a population at a particular point in time
What is a reservoir?
the organism or environment that normally harbors the pathogen
What is screening?
the systematic diagnostic testing to detect asymptomatic or subclinical animals for the purpose of control or prevention of disease
What is a source?
the place where the pathogen passes directly to a susceptible house
What is a sporadic disease?
a disease that occurs irregularly and haphazardly
What is sylvatic?
occurring or affecting wild animals
What is threshold level?
the minimum concentration of a pathogen in the hosts circulation that allows successful transmission to an arthropod vector
What is a wildtype virus?
denotes the original virus circulating in nature from which mutants arise
What is zoonosis?
a disease that primarily affects vertebrate animals but that can be transmitted to humans
What is disease prevention?
refers to those measure designed to exclude disease from an unaffected population
What is disease control?
refers to the reduction of the morbidity/mortality from disease
What is disease eradication?
describes efforts to eliminate selected organisms from a defined area
What is quarantine?
limitation of freedom of movement of animals to prevent the spread of a disease to other members of a population
What is test and slaughter?
involves a method of case finding, usually by means of an immunologic screening test and the killing of test-positive animals
What is depopulation?
elimination of all susceptible hosts on a herd or clock or area basis
What is Acyclovir (valtrex)?
synthetic analong of deoxyguansine to restrict the herpes virus
produces inactive drug and becomes active with triphosphate
it inhibits viral DNA polymerase thus blocking synthesis of viral DNA
What is Amantadine (symmetrel)?
water soluble cyclic amine which specifically inhibits most strains of influenza A by blocking viral uncoating by blocking M2 ion channel
What is oseltamivir phosphate (tamiflu)?
inhibitor of neuaminidase enzyme by influenza A

minimises number of progeny virions by cleaving sialic acid residues from host cell receptors
What is Zidivudine (AZT)?
a previous anti cancer drug used and an anti HIV drug
nuclease analog
inhibits viral reverse transcriptase
blocks synthesis of proviral DNA
What are protease inhiitors?
inhibit viral proteases
blobck cleavage of viral polyprotein produce from viral polycistronic mRNA

ex) saquinavir, indinavir, rotonavir, lopinavir
What are interferons?
cytokines produces and secreted by somatic cells in response to a variety of stimuli.
What are type 1 interferons?
induce an antiviral state in uninfected cells via inhibition of viral protein synthesis, induce apoptosis in the virus infected cell and stimulated MHC class 1 proteins and proteasome proteins
What is IFN-alpha?
leukocyte interferon that is secreted by virus-infected macrophages and other leukocytes
non host specific
What is IFN-beta?
Fibroblast interferon secreted by virus infected fibroblasts and epithelial cells
generally host specific
What are type 2 interferons?
an immune interferon secreted by antigen, mitogen or cytokine stimulated T cells, labile at pH 2 and demonstrates host specificity
INF-gamma has no antiviral activity
What do NK cells do?
lyses infected cells not expressing or expressing few MHC class 1 proteins
lyses target cells via antibody dependant cell-mediated cytotoxicity (ADCC)