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24 Cards in this Set
- Front
- Back
Two characteristics of viral progeny?
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they are all clones of a single virus particle and are haploid
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Mutant viruses are usually due to what?
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misincorporation of nucleotides by viral replicase proteins, resulting in point mutations
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What aspects of the replication cycle can be altered due to viral mutations?
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1) receptor tropism
2) replication efficacy 3) altered viral targets |
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What factors may be altered by in vivo mutations?
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1) replication in novel hosts
2) conditional mutants (temperature) that often have altered pathogenicity |
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What is FluMist?
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a live, attenuated vaccine that is a viral mutant
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Types of genetic interactions between viruses?
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Complementation, Recombination, and reassortment
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What is complementation?
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when two mutants infect the same cell and each makes the protein the other lacks
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What is viral recombination?
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then two viral genomes come together and become a new one (blue and red = purple)
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What is viral reassortment?
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when genes are randomly divided into viral progeny (blue orange and red can give either blue orange or red orange or red blue progeny)
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Viruses that recombine naturally?
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coronavirus, HIV, HSV (HHC)
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Viruses that reassort naturally?
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influenza, rotavirus, reovirus (RRI)
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Ways to detect a virus?
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1) physical effects of viral replication in host cells
2) Viral Ag 3) Viral genome 4) viral itself on EM |
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How are viral antigens detected?
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In clinical sample, labelled Ab targets maybe in in cells or a released virus;
in a culture, the targets are viral proteins synthesized during replication |
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What is detected in viral serology?
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Viral serology involves detecting antibodies generated in infected host
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What information can viral serology yield?
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genus or strain similarities due to effective neutralization and cross reactivity; also teaches about the course of disease
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What is a virus titer?
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number of infetious particles
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What is used to determine if an infection is new or old?
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antibody titers
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What is used to determine the number of infectious particles in a sample?
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plaque assays
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What is a neutralization assay?
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it measures the ability of polyclonal Ab to inhibit infectivity of a known amount of virus by blocking binding to a host cell
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If Ab neutralization is effective, what result should be seen?
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reduction of pfu; this tells you that the antibody used has relevance to the test virus.
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If Ab neutralization is ineffective, what result should be seen?
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no reduction of pfu
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how is the viral genome detected?
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DNA or RNA probes and PCR
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What must be known to use probes for viral genome detection?
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previous knowledge about the squence of the viral genome
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What are two advantages of PCR for viral genome detection?
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It allows for detection of virus that is difficult to grow in cell culture and it may allow detection of very small amounts of virus.
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