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24 Cards in this Set

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