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200 Cards in this Set
- Front
- Back
What are the DNA viruses?
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Circoviridae
Parvoviridae Hepadnaviridae Papillomaviridae Polyomaviridae Adenoviridae Herpesviridae Asfarviridae Iridoviridae Poxviridae |
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What are the single stranded DNA viruses?
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Circoviridae (+)
Parvoviridae (-) |
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What are the double stranded DNA viruses?
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Hepadnaviridae
Papillomaviridae Polyomaviridae Adenoviridae Herpesviridae Asfarviridae Iridoviridae Poxviridae |
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What is the parvovirus?
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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 |
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What is the papillomavirus?
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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 |
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What is adenovirus?
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dsDNA virus
blue inclusion bodies replicate in nucleus have pentons produce Ab to epitopes resistant in environment ex: kennel cough |
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What is asfarvirus?
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dsDNA virus
red inclusion bodies replicates in the cell cytoplasm and in soft ticks Ex) african swine fever |
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What is herpesvirus?
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dsDNA virus
red inclusion bodies syncytium and fuse with neighboring cells very fragile in environment ex: feline rhinotracheitis - corneal ulcer *herpes virus mimics thymine |
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What is poxvirus?
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dsDNA virus (largest)
red inclusion bodies multiply in cytoplasm manifests in skin first small pox, cow pox survive many years |
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What is Hepadavirus?
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partially ds and partially ss DNA virus
replicates in nucleus of hepatocytes replication involves reverse transcriptase ex: hepatocytes hep B |
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What is polyomavirus?
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associated with inapparent infections
highly host specific replicate in the nucleus causes french molt and budgerigar fledgling disease in birds |
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What is circovirus?
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ssDNA virus (smallest)
blue inclusion bodies produced replicates in the nucleus large inclusions stable in environment ex) chicken anemia |
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What DNA viruses show blue inclusion bodies?
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adenovirus
circovirus |
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What DNA viruses replicate in the cytoplasm?
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Asfarvirus
Poxvirus |
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What DNA viruses have red inclusion bodies?
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Parvovirus
Asfavirus herpesvirus poxvirus |
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What DNA viruses have no inclusion bodies?
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papillomavirus
hepadnavirus |
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What is a virus?
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"Fluid poison"
used to describe infections agents that passed through bacteriologic filters |
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What is a host range for viruses?
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range of animal species and tissue cells that the virus can infect - broad or limited
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What is a structural unit?
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protein subunit which may be assembled into capsomers - can have one or more subunits
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What is a capsomere?
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morphological subunit from which the virus capsid is built
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What is a capsid?
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protein shell or coat that encloses the nucleic acid genome
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What is a nucleocapsid?
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the capsid together with enclosed nucleic acid
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What is a virion?
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the complete infective virus
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What is an incomplete virion?
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viron without the nucleic acid
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What is a defective virus?
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a virus that can not replicate because it lacks full complement of viral genes
replication occurs in mixed infections with helper virus example: pseudotype |
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What is a pseudotype?
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during replication in co-infected cells the genome of one virus may become encapsulated in the heterologous protein coat encoded by a second virus
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What is a pseudovirion?
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during viral replication the capsid sometimes encloses host nucleic acid and therefore does not replicate
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What is an episome?
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Autonomouse extra-chromosomal genetic element that can be integrated with chromosomal DNA
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What is a provirus?
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viral DNA that is integrated into a host cell chromosome in a latent state and must be activated before it is transcribed
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What are the architectures of capsids?
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Icosahedron = cubic
Helical- usually encapsulated Complex ex poxvirus |
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What are the functions of capsids?
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structural symmetry
protection of nucleic acid facilitates attachement determines antigentic characteristics |
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What is a viral envelope?
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acquired from cellular membranes
occurs only at sites where virus specific proteins have inserted into host cell |
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What are enzymes transcribing the viral genome into mRNAs?
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DNA dependent RNA polymerase such as pox and asfivirus
RNA dependent RNA polymerase uses (-) sense genome * host cells lack this enzyme |
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What are enzymes involved copying virion RNA to DNA?
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RNA dependent DNA polymerase (reverse transcriptase) in hepadnavirus and retroviruses
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What are enzymes that copy the nucleic acid genome?
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DNA dependant DNA polymerase
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Stability of viruses: which is more stable?
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Naked viruses survive well inside and outside the body
Enveloped viruses are more susceptible to environment factors which include temperature and pH |
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What are the RNA viruses?
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Picornaviridae
Caliciviridae Togaviridae Arteriviridae Flaviviridae Reoviridae Birnaviridae Coronaviridae Paramyxoviridae Orthomyxoviridae Rhabdoviridae Retroviridae Bunyaviridae Bornaviridae Arenaviridae |
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What is the picoravirus?
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Small stable ssRNA (+) virus
replicates in the cytoplasm no inclusions causes foot and mouth, common cold, ulceration, polio and hep A |
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What is the calicivirus?
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ssRNA virus (+) replicates in cytoplasm, no inclusions
causes feline calici virus, ulceration on tongue and hep E, lagovirus (bunnies) |
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What is the togavirus?
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ssRNA virus (+) with an envelope and icosahedral nucleocapsid
replicates in the cytoplasm - budding causes EEE in horses and Rubella in humans |
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What is the Arterivius?
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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 |
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What is the Flavivirus?
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ssRNA virus (+) with envelope
replicates in the cytoplasm labile in environment causes yellow fever, bovine viral diarrhea |
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What is the reovirus?
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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 |
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What is the Birnavirus?
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dsRNA virus
replicates in cytoplasm stable in environment causes infections bursal disease (decrease B lymphocytes) |
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What is the coronavirus?
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enveloped ssRNA virus (+)
replicates in the cytoplasm budding in ER and golgi narrow host range moderately resistant no inclusions causes FIP - immune complex hypersensitivity |
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What is the Paramyxovirus?
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ssRNA (-) virus
large helical nucleocapsid with envelope red inclusions in cytoplasm syncytium labile in environment causes canine distemper and human measles |
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What is the orthomyxovirus?
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ssRNA virus (-)
replicates in cytoplams and nucleus - budding labile in environment causes influenza A, B and C segmented genome - multipartite |
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What is the rhabdovirus?
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ss RNA virus (-)
replicates in the cytoplasm produces inclusions (negri bodies) broad host range rapidly inactivated by UV light Causes rabies |
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What is the retrovirus?
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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 |
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What is the Bunyavirus?
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ssRNA virus (-)
replicates in cytoplasm transmitted by arthropods and rodents labile in environment causes huntavirus |
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What is the bornavirus?
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ssRNA virus (-)
spherical and enveloped replicates in nucleus and produces large inclusions has affinity for nervous tissue labile in environment causes meningeoencephalomyelitis |
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What are the (-) RNA viruses?
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Orthmyxooviridae
Paramyxoviridae Rhabdoviridae Bunyaviridae Bornaviridae Arenaviridae |
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What is the arenavirus?
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ssRNA virus (-)
replicates in the cytoplasm budding in plasma membrane causes chronic infections hemorrhagic fever |
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What is cell culture?
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it involves the growth of dispersed animals cells in vitro or as cells in suspension as a monolayer
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What is a primary cell culture?
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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 |
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What is serially propagated cell cultures?
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diploid cell line
homogenous population from human embryos or subcultures of a primary culture produces 100 cultures used to produce some viral vaccines |
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What is a continuous (heteroploid) cell line?
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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 |
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How do you prepare a monolayer cell culture?
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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 |
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What is a shell vial cell culture?
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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
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What are co-cultivated cells?
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cells of different types grown together as a single monolayer
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What are embryonated eggs?
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developed by goodpasture 1930
contain Ab to a virus not suitable for isolation of viruses between 5 -13 days old |
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What are the routes on inoculation of embryonated eggs?
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yolk sac
chorioallantoic amniotic allantoic intravenous |
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How do you inoculate an egg by the yolk sac?
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at 5-7 days
22 G 1 1/2 needle for togavirus and avian enterovirus |
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How do you inoculate an egg by chorioallantoic site?
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9 - 12 days
26 or 28 G needle used for pox and herpesvirus |
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How do you inoculate an egg by amniotic site?
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7-13 days
26 G needle influenza (orthomyxovirus) |
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How do you inoculate an egg by intravenous
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10 - 12 days
used for bluetongue virus (reovirus) |
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What are good incubation conditions for an embryonated egg?
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good air circulation
temp of 37C automatic turning racks 62% humidity |
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What are signs of viral growth in an embryonated egg?
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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 |
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When are lab animals used?
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used if infectious agent can not yet be grown in cell culture
used to study path mechanisms and study serology |
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What do we concentrate and purify viruses?
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to study the physiochemical characteristics, infectivity, antigenic properties of a virus
centrifugation with sucrose or cesium chloride |
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What is a virus titration?
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quantitative determination of viral activity, the concentration of virus in the sample which can produce disease, lesions or a recognizable effect in the host
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What is a virus titer?
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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 |
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What is a quantitative assay?
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used to measure exact number of infectious virus particles in a sample (monolayer)
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How is a virus titer determined?
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number of plaques counted multiplied by the reciprocal of the dilution and by a factor to express in PFU/mL
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What is a pock assay?
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titration of certain viruses like pox and herpes on chorioallantoic membrane
looks are the number of necrotic areas |
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What is a transformation assay?
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oncogenic viruses transform cells so that they display decreased contact inhibition creating a microtumor
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What is a quantal assay?
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shows presence or absence of infection. does not measure exact number
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What is a permissive cell?
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contains the necessary intracellular components needed for virus replication
productive infection |
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What is a nonpermissive cell?
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a cell type that does not allow a complete virus replication cycle
abortive or non productive infection |
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What is multiplicity of infection (MOI)
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number of infections viruses inoculated per cell
~ 5-10 per cell |
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What is an eclipse period?
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time between disappearance of infectious virions (uncoating) and appearance of 1st progeny virions intracellulatly ~2-12 hours
seen in enveloped viruses |
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What is a latent period?
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extracellular virions that are not detectable
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What is the viral replication cycle?
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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 |
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What is adsorbtion?
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attachment
binding to receptors on the plasma membrane of a cell |
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What is a co receptor?
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number of viruses, successfully infect a cell requiring a cellular receptor for its co receptor
see in HIV |
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What is penetration?
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engulfment or viral uptake
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What is cell mediated endocytosis?
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selective binding of ligands to specific cell membrane receptors
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What is transcription?
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nucleic acid molecule transferred to mRNA
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What is capping?
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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
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What is the poly A tail?
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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
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What is the splicing of viral pre mRNA
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involved deletion of intervening non coding sequences (introns) and the ligation of non noncontinuous sequence (exons) by spliceasomes
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What is the cytopathic effect?
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visible or morphologic change induced in a host cell by a virus that may result in cell damage or death
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What are inclusion bodies?
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a morphologic change in cells by some viruses and are recognized by H and E stain or by fluorescence microscopy
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What are mechanisms of cell damage in cytocidal viral infections?
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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 |
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What are examples of noncytocidal changes in virus infected cells?
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persistant infections like most retroviruses (slow progression over time)
damage to homeostatic functions |
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What is cell transformation?
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The changing of a normal cell into a cancer cell
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What are proto-oncogenes?
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genes whose protein products function in the signal tranduction pathways that control normal cell growth, division and differentiation
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What are cellular oncogenes?
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genes whose products can transform normal cells when expressed abnormally or in excess from the corresponding proto-oncogenes
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What are tumor suppressor genes?
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encode proteins that normally act to inhibit cell proliferation during the G1 phase
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What is the Rb protein?
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retinoblastoma protein
tumor suppressor protein that is dysfuntional in many cancers protein inhibits the entry of cells into S phase |
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What is p53
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required for apoptosis induced by DNA damage
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What are the stages of the cell cycle and what happens during each stage?
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G1 - cell growth
S - DNA replication G2 - cell growth M - division |
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What family of viruses for RNA tumor viruses belong to?
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Retroviridae
major causes of lymphoma and leukemia |
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What are acute transforming viruses?
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v-onc+
derived from host cell proto-oncogenes and occasionally the proto-oncogene becomes incorporated in the viral genome (defective) |
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What are chronic retroviruses?
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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 |
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What is a mutation?
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a heritable change in the nucleotide sequence of the genome of an organism
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What is an escape mutant?
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mutants affecting antigenic determinants of virion surface proteins
result in persistent infections due to being able to replicate in the presence of the antibody |
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What are conditional-lethal mutants?
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viruses that can replicate only in certain conditions
Ts mutants = temperature sensitive |
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What are defective interfering mutants?
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a virus that lacks one or more functional genes required for viral replication due to a deletion mutation
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What is a dual infection?
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2 dissimilar viruses that may replicate within the same cell as efficiently as in single infection
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What is a genetic interaction?
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interactions involving the genomes of the parental virions
resulting progeny are genetically different from either parent |
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What is genetic recombination?
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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
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What is genetic reassortment?
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exchange of complete RNA molecules between genetically related viruses with segmented genomes
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What are nongenetic interactions?
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products of the genes that interact rather than genomes
progeny are similar to parents |
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What is phenotypic mixing?
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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 |
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What is viral interference?
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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 |
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What is pathogenicity?
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The ability of an organism to cause disease by overcoming the defenses of the host
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What is virulence?
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the capacity of a microorganism compared to other closely related microbes to produce disease in infected host
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What are susceptible cells?
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virus infected cells whose infection may not be sufficient to cause clinically demonstrable disease
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What are target cells?
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virus infected cells whose infection usually contributes to clinically demonstrable disease
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What are clinical signs?
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and objective evidence or manifestation of an illness
what we see as a clinician |
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What are clinical symptoms
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any subjective evidence of disease
what the patient is feeling based on disease |
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What are portals of entry for microorganisms?
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skin
mucus membranes respiratory tract gastrointestinal tract |
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What are some examples of virus spreading?
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locally
subepithelially by lymphatics hematogenous |
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What is viremia?
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the presence of infectious virus particles into the bloodstream
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What is passive viremia?
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direct introduction of viruses into the blood steam
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What is active viremia?
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invasion of bloodstream by progeny
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What is primary viremia?
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release of progeny virions into the blood after initial replication at the portal of entry
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What is secondary viremia?
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delayed appearance of high concentration of infectious virus in the blood as a result of disseminated infections
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How are viruses cleared from the blood?
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mononuclear phagocytes in the spleen, liver and bone marrow
Ab clearance complement mediated clearance |
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What is teratogenesis?
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abnormal development or arrest in development of the embryo or fetus which may result in death or malformation
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What is inapparent (subclinical) infection?
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observed in many viral infection where the individual does not have a noticeable illness
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What is immunopathology?
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tissue damage mediated by hypersensitivity reactions
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What is a persistent infection?
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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
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What is epidemiology?
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the study of the occurrence of disease in a population
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What are types of vector transmission?
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biological
mechanical vehicle |
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What is biological transmission?
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part of the life cycle that takes place in a vector
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What is mechanical transmission?
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arthropod being a passive carrier
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What is a vehicle?
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food, blood, milk water, drugs
places to pick up pathogens |
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Hos is case fatality calculated?
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number of deaths/number of sick X 100
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How is mortality rate calculated?
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number of deaths/ total population X 100
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What is horizontal transmission?
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transmission of infection from individual to a population
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What is vertical transmission?
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transmission of infection from parent to offspring
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What is an iatrogenic infection?
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infection transmitted from a health care provider to a patient
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What is a nosocomial infection?
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hospital or clinic acquired infection
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What is herd immunity?
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the immune status of a population rather than an animal or individual
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What are some agent vectors?
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infectivity
virulence transmission efficiency exogenous pathogens endogenous pathogens |
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What are factor environmental factors that cause disease?
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season of the year
overcrowding environmental contamination reservoir population arthropod vectors |
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What are the stages of disease?
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inoculation
prodromal illness decline convalescence |
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What is Chemotherapy?
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the treatment of infectious disease with chemicals or antibiotics that are inhibitory or lethal to the infectious agent
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What is selective toxicity?
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the property of antimicrobial agent to be toxic for a microbe and nontoxic for the host
paul-ehrlich "father" of modern chemotherapy? |
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What is a macule?
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virus replication in the dermis leads to flat, reddened lesion produced by a lasting local dilation of dermal blood vessels
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What is a papule?
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a raised macule due to localization edema and cellular infiltrates
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What is a vesicle?
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virus replication spreads from the dermis to the epidermis resulting in a small circumscribed epidermal elevation that contains a clear fluid
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What is a pustule?
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A vesicle with copious neutrophil infiltration.
Localized erosion or sloughing of endothelium results in ulceration |
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What is an arbovirus?
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viruses that multiply in a arthropod vector
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What is case?
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an animal suffering from a clinically diagnosable disease
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What is case-fatality rate?
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the number of deaths among the clinically ill
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What is a carrier?
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any animal that sheds an infectious agent without demonstrating clinical signs
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What is an incubatory (acute) carrier?
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animals that excrete agent during the disease's incubation period
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What is a convalescent chronic) carrier?
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an animal that sheds the infectious agent when they are recovering from a disease
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What is a communicable period?
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the time during which the infectious agent may be transferred, directly or indirectly from an infect animal to another
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What is a contagious disease?
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an infectious disease in which the pathogen may be transmitted from one host to another by direct or indirect contact
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What is a dead end host?
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one that is not involved in maintaining a virus; host does not transmit an infectious agent to other animals or vectors
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What is a disease?
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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
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What is an endemic?
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the constant or usually expected occurring of a disease with a given geographic location
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What is an epidemic?
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major increase in disease incidence affecting either a large number of animals or spreading over a large area
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What is an exotic?
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a disease not known to occur in a particular country or geographic area
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What is a field isolate?
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a fresh virus isolate from the natural host
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What is a fomite?
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an inanimate object or other vehicle involved in the transfer of infectious agents from one host to another
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What is an incidence?
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the number of new cases that occur in a population over a specified period of time
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What is an incubation period?
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The period of time between an infection and the development of signs and symptoms
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What is an infection?
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invasion and multiplication of microorganisms in body tissues
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What is a pandemic?
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a geographically widespread epidemic
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What is prevalence?
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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
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What is a reservoir?
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the organism or environment that normally harbors the pathogen
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What is screening?
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the systematic diagnostic testing to detect asymptomatic or subclinical animals for the purpose of control or prevention of disease
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What is a source?
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the place where the pathogen passes directly to a susceptible house
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What is a sporadic disease?
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a disease that occurs irregularly and haphazardly
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What is sylvatic?
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occurring or affecting wild animals
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What is threshold level?
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the minimum concentration of a pathogen in the hosts circulation that allows successful transmission to an arthropod vector
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What is a wildtype virus?
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denotes the original virus circulating in nature from which mutants arise
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What is zoonosis?
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a disease that primarily affects vertebrate animals but that can be transmitted to humans
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What is disease prevention?
|
refers to those measure designed to exclude disease from an unaffected population
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What is disease control?
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refers to the reduction of the morbidity/mortality from disease
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What is disease eradication?
|
describes efforts to eliminate selected organisms from a defined area
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What is quarantine?
|
limitation of freedom of movement of animals to prevent the spread of a disease to other members of a population
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What is test and slaughter?
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involves a method of case finding, usually by means of an immunologic screening test and the killing of test-positive animals
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What is depopulation?
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elimination of all susceptible hosts on a herd or clock or area basis
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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
|
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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 |
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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 |
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What are interferons?
|
cytokines produces and secreted by somatic cells in response to a variety of stimuli.
|
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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
|
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What is IFN-alpha?
|
leukocyte interferon that is secreted by virus-infected macrophages and other leukocytes
non host specific |
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What is IFN-beta?
|
Fibroblast interferon secreted by virus infected fibroblasts and epithelial cells
generally host specific |
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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 |
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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) |