Viral Genetic Variability

Question 1

viral swarm concept

Answer 1

*many viruses make an unbelievable number of mistakes when new virus genomes are made
*when we have a virus infection, our bodies really are infected with a SWARM of genetically different viruses

Question 2

antigenic DRIFT

Answer 2

a mechanism for variation in viruses that involves the ACCUMULATION of mutations within the genes that code for the proteins that have antibody-binding sites
*due to the lack of proofreading abilities of RNA-dependent RNA polymerase
*results from POINT MUTATIONS

Question 3

examples of viruses with high levels of antigenic DRIFT

Answer 3

Rhinovirus - escapes neutralizing antibodies because changes can occur on the surface of the capsid (this is why you keep getting colds forever)

Question 4

antigenic SHIFT

Answer 4

the process by which 2 or more different strains of a virus (or 2 or more different viruses) combine to from a NEW SUBTYPE having a MIXTURE of the surface antigens of the 2+ original strains
**RECOMBINATION BY REASSORTMENT (SEGMENTED GENOMES)

Question 5

example of antigenic SHIFT

Answer 5

Influenza - can show dramatic antigenic shift by REASSORTMENT

Question 6

consequences of viral mutations

Answer 6

-antibody escape mutations
-immune cell escape mutations
-drug resistance
-loss or gain of the ability to infect a new host
-changes to virulence or growth properties