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156 Cards in this Set
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Suffixes used for viruses of the same
-order -family -subfamily -genus |
-order: virales
-family: viridae -subfamily: virinae -genus: virus |
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What is a positive sense RNA virus mean regarding the genome?
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An RNA genome that con be directly translated into proteins
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What is a negative sense RNA virus mean regarding the genome?
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Frequires formation of a complementary positive strand prior to translation of proteins
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Define ambisense
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single-stranded RNA viruses that contain stretches of both positive and negative sense.
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True/False. All virus genomes are haploid.
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False. The exception are the retroviruses, which are diploid.
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What types of nucleic acids are found in nonsegmented viral genomes?
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ssRNA
ssDNA dsDNA |
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True/False. Genomes can be linear or circular.
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True.
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What type of genome do the papillomaviruses, polyomaviruses and hepadnaviruses share?
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Circular dsDNA
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What genus of animal viruses have a circular ssDNA genome?
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circoviruses
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Which genus of animal viruses have linear ssDNA genome?
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parvoviruses
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What genomic form is typical of DNA viruses?
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Nonsegmented, linear dsDNA
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It is speculated that RNA viruses evolved from an mRNA molecule. Why?
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All RNA viruses except retroviruses and orthomyxoviruses are missing introns.
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Which viruses have a reverse transcription phase in their lifecycle (where RNA is converted to DNA)?
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Retroviruses (RNA viruses)
Hepadnaviruses (DNA viruses) |
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True/False. Splicing of DNA transcripts is common among DNA viruses.
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True.
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In general, DNA viruses are characterized by what type of replication?
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nuclear
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True/False. RNA viruses use host machinery to replicate their genome.
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False- Efficient RNA replication is not a characteristic of the host cell. RNA viruses enode their own enzyme for replication.
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Define nucleocapsid.
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The complete protein-nucleic acid complex that is the packaged form of the genome in a virus particle.
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True/False. A viral envelope prevents dessication of a virus.
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False. Makes more susceptible to dessication but usually plays a major role in interacting with host cell membrane.
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Viral envelope lipids are cell-derived, but where do most of the proteins in the envelope come from?
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They are virus-encoded.
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Is the genome of the - sense RNA viruses itself infective?
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No- needs viral proteins to transcribed to + sense RNA before being translated.
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What are 3 routes of escape of quasispecies variants (from immune response?)
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1) modify envelope to evade antibodies
2) enhance replication in macrophages 3) reduce expression of viral antigens (enhances long term survival but not spread) |
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What are the 2 cell culture methods used for studying viruses discussed?
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Bacterial plaque assay
Serum-virus mixtures innoculated into cell cultures and compared to virus only cultures. Presence of antibody in the serum protects the cells from damage. |
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How is hemagglutination used to study viruses?
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Ability of serial dilutions to hemagglutinate RBCs give relative titers.
Test a serum for ability to block hemagglutination by presence of antibodies. |
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In a complement-fixation test, what conclusions can be reached if the RBCs lyse?
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Absence of viral antibody to fix viral antigen and sequester complement from acting on sensitized RBCs.
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Coggins test
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Antigen and antibody specific antigen placed in separate wells on agarose plate. Line appears where they diffuse and precipitate.
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Birnaviridae
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Beetle
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RNA
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Pox
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Box Elder
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Bunya
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Bunny
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Corona
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crow
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Calici
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katydid
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Toga
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Dog
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Flavi
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Flamingo
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Herpes
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Hickory
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Orthomyxo
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Oriole
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Papilloma
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papaya
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Circo
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celery
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Paramyxo
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parakeet
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Parvo
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Parsnip
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Arteri
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aardvark
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Picorna
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pickerel
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Rhabdo
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rabbit
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Adeno
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Radish
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Reo
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Ray
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Retro
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petrel
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Arena
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wren
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Professional antigen presenting cells engulf virus particles and present them on what type of molecule in what process?
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MHC class II
Exogenous |
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What is the role of Th1 cells?
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produce cytokines (IL12, INFg) to promote cell-mediated Tc response
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What is the role of Th2 cells?
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Promote B cell response against T cell dependent antigens by producing, among others, IL-4 and IL-6
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What types of antigens to toll-like receptors bind?
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various viral, bacterial and fungal pathogens.
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Which innate immune pathway recognizes intracellular viral dsRNA?
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Retinoic acid inducible gene-1 (RIG-1)
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What is the cascade of the RIG-1 pathway?
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Involves Mitochondrial anti-viral signaling protein (MAVS), responsible for inducing interferons which recruits inflammatory cells of the adaptive response.
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How can viruses block the RIG pathway?
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RNAi of MAVS will increase susceptibility to the virus, or cleavage of MAVS will suppress host immune system.
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Which viruses are protected from GI destruction by the buffering capacities of milk?
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bovine and porcine coronaviruses
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What are the 3 major routes of systemic spread of viruses?
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Cell-to-cell
bloodstream nervous system |
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Three things that determine tissue tropism of a virus.
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Route of infection
interaction of attachment protein with receptor on host cell replication requirements of the virus |
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Define abortive infection.
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Virus infects cell but cannot complete full replication cycle.
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What is a persistent infection versus a latent infection?
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persistent- replicate in host for hosts lifetime
latent- virus is in inactive state |
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Name 3 mechanisms of viral persistence.
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reduction of viral cytopthic effect
viral genome maintenance evasion of host immunity |
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Name direct cytopathic effects a virus can induce.
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altered shape
detachment from the substrate lysis membrane fusion membrane permeability formation of inclusion bodies apoptosis |
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How might a virus induce autoimmunity?
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molecular mimicry
bystander activation immune dysregulation alteration of self molecules |
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How might viruses promote cancer growth?
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Subvert process of apoptosis, resulting in immortalization, the first step in oncogenesis.
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What is one way we could increse the chemotherapeutic index of an antiviral?
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Use a drug that must be metabolized by a viral enzyme to be activated
ex- thymidine kinase |
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What is an example of a biological response modifier useful in viral treatment?
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Zinc enhances macrophage activity
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This disease is characterized by degeneration of ventral spinal cord gray matter.
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Teschen's Disease, a picornavirus.
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Foot and Mouth
Teschen Disease SMEDI Avian Encephalomyelitis |
Picornaviruses
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Other than feline calicivirus, which other diseases are caused by calici?
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Viral hemorrhagic Disease of the rabbit
Vecsicular Exanthema Virus |
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Name the small (+) sense RNA viruses
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Picornaviruses
Calicivirus Hepeviridae Astroviridae Flaviviridae Togaviridae |
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Rabbit presents with foamy nasal discharge, seizures and opisthotonos.
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Result of acute liver failure due to viral hemorrhagic disease caused by a calicivirus.
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Bovine Diarrheal Virus is from which family of viruses?
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Flaviviridae
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How do more cytopathic forms of BVD develop?
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Nonhomolgous recomination event with cellular RNA, usually a transcript for ubiquitin.
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"Hairy Shaker Lambs"
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Border Disease, a flavivirus similar to BVD
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What causes the lesions of Hog Cholera, a flavivirus of swine?
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Propensity to injure endothelial cells- hemorrhage in LN, kidneys, bladder, skin.
Ischemia and neuronal death. |
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Horse with hindlimb weakness, lower lip paralysis, fever, ataxia, convulsions.
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West Nile Virus.
Flaviviral encephalitis with lymphocytic perivascular cuffing. |
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Name the togaviruses studied.
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EEE
WEE VEE (Rubella) |
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BVD
Hog Cholera Border Disease |
Pestiviruses of the family flaviviridae
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Diseases caused by coronaviruses
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FIP
Calf coronavirus Transmissible Gastroenteritis Hemagglutinating Encephalomyelitis |
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Lymphoid liver tumors in birds could be which 2 viruses?
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Avian leukosis virus (alphretrovirus) or Marek's disease
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Infection by this virus can cause osteopetrosis in birds.
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Avian leukosis virus
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Whhich viruses are unique in inducing tumors of the respiratory tract?
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Ovine Pulmonary adenomatosis (Jaagsiekte)
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Mouse mammary tumor virus transforms cells by what mechanism?
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Cis-activation
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Unlike all other viruses, these are diploid.
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Retroviruses
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True/False. Inheritance of an endogenous provirus is of little pathogenic consequence.
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True, with some exceptions (mouse mammary tumor virus).
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True/False. Transducing viruses containing cellular oncogenes are usually defective and require a nondefective helper virus to provide viral products they lack through phenotypic mixing.
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True.
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This is the most important disease of goats in the U.S.
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Caprine arthritis and encephalomyelitis (CAE)
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What does maedi mean? Visna?
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Maedi- dysnpea
Visna- wasting |
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What does the Coggins test evaluate for?
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Equine Infectious Anemia
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Horse with severe anemia, icterus, edema and petechial hemorraghes in mosquito country.
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Equine infectious anemia.
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What is TRAIL and its significance in immunosuppression viruses?
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tumor necrosis factor-related apoptosis inducing ligand
Stimulates apoptosis of Th cells |
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True/False. dsDNA viruses must have nuclear transcription.
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False. Could be cytoplasmic or nuclear.
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This virion looks like a pineapple.
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Poxvirus.
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What are the functions of secreted poxvirus proteins?
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Homology to epidermal growth factor
Downregulation of complement Soluble receptors for host cytokines |
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What are the rarely fatal poxviruses?
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Papular stomatitis
Contagious ecthyma Swinepox Fowlpox Vaccinia and cowpox |
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What are the usually fatal poxviruses?
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Squirrel fibroma virus
Myxomatosis |
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Replication of which viruses involves concatemeric intermediates?
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Poxviruses
Herpesviruses |
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Virions of this family of viruses have a layer of globular material surrounding the capsid called the tegument.
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Herpesviruses
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Functions of the latency-associated transcript of herpesviruses?
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Inhibit virus replication
Promote survival of infected cells by blocking enzyme pathways involved in apoptosis. |
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True/False. Latency of herpesviruses may require persistent lymphocytic cell infiltration.
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True.
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Strong viral candidate(s) for etiological agents of Alzheimer's?
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Herpesvirus-1
______ |
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Which herpesvirus causes immune complex vasculitis?
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malignant catarrhal fever
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Which herpesvirus causes neoplasia?
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Marek's Disease
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Which herpesviruses cause upper respiratory disease?
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Infectious bovine rhinotracheitis
Equine rhinopneumonitis Feline Viral Rhinotracheitis Avian laryngotracheitis |
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Which herpesviruses cause silent infection in adult natural host but fatal infection in neonate or aberrant host?
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canine herpesvirus
pseudorabies herpes B herpes simplex |
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How to differentiate Herpes mammillitis from bovine poxvirus?
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Lesions are generally more ulcerative
Histo: giant cells and intranuclear inclusions in herpes |
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Role of early gene products of adenoviruses, E1A
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E1A- forms complexes with tumor suppressor Rb, increasing gene transcription for products involved in DNA synthesis.
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Role of early gene products of adenoviruses, E1B
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Inactivates p53, which accumulates with DNA damage or unscheduled synthesis to induce apoptosis.
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These families of viruses can potentially serve as vaccine vectors.
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Adenoviruses
____________ |
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Role of early gene products of adenoviruses, E3.
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Blocks transport of MHC I molecules
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True/False. A nonproductive papilloma/polyomavirus infection results in replication but not protein formation.
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False. Early proteins produced, but no DNA replication.
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Of the early proteins produced from the polyomavirus, which is the only one needed for viral replication and must interact with cellular replicative factors?
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large T antigens
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Which early protein product of the polyomavirus is primarily responsible for cell transformation?
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middle T antigen- resembles an activated growth factor receptor
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Which family of viruses have a genus that require a helper virus to be pathogenic?
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Parvoviridae (need an adeno or herpes virus)
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What is unique about the pathogenicity of feline panleukopenia virus?
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only 2 mututations were necessary for the virus to also replicate in canine host.
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Which families of viruses can potentially be oncogenic?
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Poxviridae
Herpesviridae Adenoviridae Papovaviridae Hepadnaviridae Retroviridae Flaviviridae |
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True/False: both feline panleukopenia virus and canine parvo 2 bind to the canine transferrin receptor, but only feline panleukopenia virus binds to canine transferrine receptor
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False.
Both bind feline only canine binds canine. |
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Distinguish between replication defective viruses and satellites.
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Both need a helper virus, but there is little or no nucleotide sequence similarity between satellites and hlper virus genomes.
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Factors thought to contribute to species barrier of prion disease
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sequence differences
strain of prion species specificity of another protein involved in process, a chaperone? |
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3 explanations for accumulation of aberrantly folded host proteins in the brain.
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inhibition of proteosome activity
conversion of normal protein to abnormal isoform increased rate of production |
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Which viruses have internal ribosomal entry sites +/- cap-binding complexes to outcompete cellular protein translation?
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Picornaviruses
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Which picornavirus can use humans as fomite?
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Foot and Mouth
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What is the most common source of bovine diarrhea virus in the environment?
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Calves that are infected in utero and are persistent shedders
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Which virus has a cytotoxic biotype that results from nonhomologus recombination with cellular RNA?
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Bovine Viral Diarrhea --> mucosal disease
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How to differentiate EE from WE and VE microscopically?
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EE- neutrophils prodominant
WE/VE- lymphocytes and plasma cells |
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What is unique about the transcribing mechanism of the nidovirales?
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"Nested set" transcription- Transcript dissociates from the template and reanneals downstream and uses ribosomal frameshifting
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A series of mRNAs with same 5' and 3' ends but different middles can be the result of what 2 (post)transcription mechanisms?
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Splicing (nuclear only)
Nested set transcription |
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True/False. Each transcript of a nested set is translated only up to the next gene.
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True.
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This family of viruses has no envelope but multiple capsids.
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Reoviruses
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How do the orthomyxoviridae provide primers for transcription and shut off cellular protein synthesis?
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Viral endonuclease cleaves capped cellular RNAs. Uses 5' ends as primers, effectively shuts down cellular protein synthesis.
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Defective interfering particles
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Common in influenza viruses. Accumulate in stocks of viruses that interfere with the growth of standard virus. Play a role in establishing persistent infections.
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True/False. Some paramyxoviruses have intranuclear inclusion bodies.
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True, even though paramyxoviruses replicate in the cytoplasm, viral protein enters the nucleus and causes condensation of chromatin.
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Which family of viruses may have anti-neoplastic activity?
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Paramyxoviruses, particularly Newcastle.
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A psittacine presents w/ CNS and digestive signs. What one virus should always be on the differential list for this presentation?
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Velogenic Viscerotropic Newcastle disease
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What GROUP of viruses has transcription take place in partially uncoated viral particles?
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dsRNA segmented viruses
reoviridae birnaviridae |
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Replication of these viruses is not complete until virions infect a host cell.
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Hepadnaviridae.
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In which group of viruses can subgroups cause receptor interference and prevent infection with other subgroups?
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Retroviruses
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Phenotypic mixing.
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Capsids become enclosed with an envelope from a virus from another subgroup during co-infection.
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Cis-activation
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insertion of provirus within an intron of the c-myc gene brings expression of exons of c-myc under control of viral promoter.
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Trans-activation
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non-structural viral regulatory protein could activate cellular growth regulators.
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Paramyxoviruses
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Parainfluenza 3
BRSV Distemper Newcastle Disease |
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Flaviviruses
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Bovine Viral Diarrhea
Hog Cholera Border Disease West Nile |
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Which virus studied contains ambisense ssRNA?
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Lymphocytic choriomeningitis (an arenavirus)
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Which family of viruses gets into cell by clathrin-coated pits?
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Adenoviridae
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Which families of viruses utilize nested set mRNA transcription and ribosomal frameshifting?
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Coronaviridae
Arteriviridae |
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These viruses transcribe through sequential interrupted synthesis of mRNAs from a single promoter.
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Paramyxoviridae
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"Hard bag" udder
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Ovine Progressive Pneumonia (Maedi-Visna)
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Lentiviruses affecting ruminants
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Ovine Progressive Pneumonia
Caprine Arthritis and Encephalomyelitis BIV |
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These viral diseases cause lesions of udder in cows.
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Pseudocowpox
Cowpox Herpes Mammillitis |
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Clinical significance of vesicular stomatitis (a rhabdovirus0?
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Clinically indistinguishable from FMD
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Which viruses are need to be distinguished from FMD?
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Vesicular stomatitis
Bluetongue Cowpox Malignant Catarrhal Fever |
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What could cause circling, incoordination, convulsions in pigs?
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Hog Cholera (flavivirus)
Porcine Herpes 1/Pseudorabies- piglets |
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SMEDI of swine can be caused by which viruses?
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Parvovirus
Picornavirus |
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Osteopetrosis
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Avian Leukosis Virus
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Acute onset of upper respiratory disease in birds, blood-tinged mucus and nasal discharge.
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Avian laryngotracheitis (herpes)
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This virus contains a v-onc gene and is shed in feather follicle epithelial cells.
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Marek's disease (herpes). Asymmetrical paralysis, encephalitis and T cell lymphoma.
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This virus is known for conferring split resistance.
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Arenavirus, Lymphocytic choriomeningitis virus
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Rabbit with opisthotonus, incoordination, foamy nasal discharge.
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Viral hemorrhagic disease (calicivirus)
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These viruses contain viral ribosomes in the virion.
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Arenaviridae
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