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76 Cards in this Set
- Front
- Back
Can viruses contain both DNA and RNA?
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NO
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Viruses consist of a ____________ reproductive cycle and an ________________transmissive cycle.
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-intracellular
-extracellular |
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Viroids, primarily plant pathogens, replicate in the....
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nucleus
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Virusoids, primarily plant pathogens, replicate in the....
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cytoplasm
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What type of viruses are: parvo, papova, adeno, herpes, hepadna, and pox.
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DNA
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What does an enveloped virus contain that a non-enveloped does not have?
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peplomer (glycoprotein) or spike, matrix proteins, lipids
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Does an enveloped virus survive in all seasons?
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no - it is seasonal
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Are enveloped viruses larger or smaller than non-enveloped?
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larger
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What composes the non-enveloped viruses?
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only the nucleocapsid
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Are non-enveloped viruses more likely to cause acute or chronic infections?
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acute
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Are enveloped viruses more likely to cause acute or chronic infections?
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chronic
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What is the largest and smallest of the virions?
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largest - pox
smallest - parvo/picorna |
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Are all animal helical viruses enveloped or non?
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enveloped
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What are the four components to a virus?
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-nucleic acids
-proteins -carbohydrates (glycoproteins) -lipids |
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Do introns code for proteins?
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no
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Can RNA viruses be circular?
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no they are always linear
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The word - virales at the end of the word meant that it is in what? (order, family, genera, or species)?
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order
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The word - Viridae at the end of the word meant that it is in what? (order, family, genera, or species)?
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family
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The word - virus at the end of the word meant that it is in what? (order, family, genera, or species)?
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genera
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What does an arbovirus mean?
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arthropod borne
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What type of characteristics are described in the following names of viruses?
-picornavirus -togavirus -retrovirus |
-picorna (small, RNA)
-toga (mantle, surrounding the membrane) -retro (reverse, reverse transcription) |
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What does the papovavirus describe?
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-pa = papilloma
-po = polyloma -va = vacuolating virus |
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How do the following names decribe where the virus was isolated?
-reoviruses |
-re = respiratory, e = enteric, o = orphan
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What does permissivity mean?
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ability to replicate and produce progeny viruses
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What are the steps to the virus replication cycle?
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1 - attachment
2 - penetration 3 - uncoating 4 - transcription of early mRNA 5 - translation of early proteins 6 - replication of viral DNA 7 - transcription of late DNA 8 - transcription of late proteins 9 - assembly of virions |
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Is energy or temperature required for attachment?
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no
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Describe the attachement process in one word?
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highly specific
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Is energy required for penetration?
What are the 3 types of penetration. |
yes
-translocation, endocytosis, fusion |
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How is penetration achieved with enveloped viruses?
with non-enveloped viruses |
endocytosis (some with fusion)
-translocation |
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What are virokines?
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they modulate infection in the uninfected cell by - negating the effects of interferon, TNF, ect, and reducing inflammatory response
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Where do most RNA viruses replicate?
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in the cytoplasm
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Why are most RNA viruses prone to mutation?
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don't have proof-reading ability in it spolymerase
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Can cells replicate RNA genome?
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no - RNA viruses must encode (ss+) or carry (ss-) an RdRp.
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Which of the DNA viruses does not replicate in the nucleus?
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poxvirus
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Where do most DNA viruses replicate?
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nucleus
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Do early or late genes encode for nonstructureal proteins?
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early
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Do early or late genes encode for structural proteins?
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late
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What does DNA polymerase need to replicate the viral genome?
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a primer
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Is the poxvirus more or less dependent on the host for replication?
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less --> larger DNA viruses have more control over the replication of their genomes and are less dependent on the cells
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What do ds DNA viruses use to transcribe viral RNA and translate viral proteins in the nucleus?
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use cellular enzymes
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What type of proteins are the non-structural ones that are produces early in transcription in ds DNA?
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regulatory
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Why is it the pox virus replicates in the cytoplasm, even though all of the other DNA viruses replicate in the nucleus?
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host transcriptional factors are not needed and thus replication can take place in the cytoplasm - the poxsvirus is the largest virus and carriers everything it needs with it for transcription and translation
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Are naked ds DNA viral genomes infectious?
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yes
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Where do parvoviruses (autonomous) replicate?
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ONLY in the nucleus of rapidly dividing cells
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Where do adeno-associated parvoviruses (dependovirus) replicate?
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only in cells co-infected with adenovirus (helper virus)
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What must first occur with the replication of the ss DNA viruses?
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the synthesis of a strand of DNA complementary to the single-strand parental viral DNA in the nucleus
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What three things add to an inherited error-prone mutation ability?
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1 - poor fidelity of the viral polymerase
2 - rapid rate of genome replication 3 - RNA viruses lacking proof-reading mechanism |
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Reassortment occurs in what type of viruses?
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those with segmented genomes --> results in a new hybrid
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What does cytopathic effect (CPE) mean?
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morphological changes of infected cells such as rounding, lysis, detachment, syncytia, inclusion bodies
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What are the 2 causes of CPE?
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1 - direct injury to infected cells (pathology)
2 - side effect - altered metabolism due to virus replication |
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What is the exception to the rule for RNA viruses replicating in the cytoplasm?
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coronaviruses and orthomyxoviruses and retroviruses
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What are the steps to macromolecular synthesis?
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1 - early mRNA transcription and protein synthesis --> NS proteins
2 - replication of viral genome 3 - late mRNA transcription and proteins synthesis --> structural proteins 4 - PTM of proteins |
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What does attachment mean?
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when VAPs (viral attachment proteins) bind to receptors on the cell
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Where are VAPs on:
-non-enveloped viruses -enveloped viruses |
- part of the capsid or a protein extending from the capsid
- spike or peplomer glycoproteins on the envelope |
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What is the target cells for the influenza A virus?
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epithelial cells - sialic acid is the receptor
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What type of enzyme do most DNA viruses use to transcribe viral mRNA?
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DNA-dependent RNA polymerase II
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ALL DNA viruses but this one's naked genome can self-initiate replication upon injection into a susceptible host.
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poxvirus
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ALL (+) sense RNA viruses but this one's can self-initiate replication upon injection into a susceptible host.
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retrovirus
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What is a characteristic effect for several enveloped viruses?
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formation of syncytia - fusion of cells
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What are inclusion bodies?
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cytoskeletal components incorporated into infected cell structures
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What are the five routes of entry of viruses?
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1 - Respiratory Tract
2 - GI tract 3 - Conjunctiva 4 - genitourinary tract 5 - skin (epidermis) |
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high viremia=
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virulence
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What is the transport speed for neural spread of viruses?
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2-16mm/day along nerve axons
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What are the routes of virus shedding?
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1 - skin
2- respiratory secretions 3 - saliva 4- feces 5 - genital secretions 6 - urine 7 - milk |
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What type of antibody is IgA?
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local, mucosal diseases
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What type of antibody is IgG?
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systemic spread/viremia, virus in cells not affected by Ab
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What types of Ig are gotten from colostral means?
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IgA
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What types of antibodies are gotten from milk, transplacental, and translocation across the GI, providing systemic protection against viremia?
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IgG
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What is important for the protection of young - passive immunity?
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early and continuous suckling
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What Ig is important in intestinal diseases?
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IgA
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What is the major Ig in cattle, swine and horses colostrum?
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igG
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What is the major Ig in dog's colostrum?
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IgA
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What is the major Ig in milk of swine, horse and dog?
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IgA
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What is the most effective type of vaccine?
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MLV
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Does a MLV or a killed vaccine have a lower level and shorter duration of immunity?
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killed
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What antibody class is activated in live vaccines and killed?
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live - IgG and IgA
killed - IgG |