viral genetics

Question 1

are virus genes eukaryotic or prokaryotic? what are they comprised of?

Answer 1

Eukaryotic
Enhancer and promoter region
ribosomal entry site
open reading frame

Question 2

what are the 4 ways that viruses comprise their genetic info into a small space?

Answer 2

overlapping reading frames
translational frame shifts
splices
polyproteins

Question 3

what viruses are less stable: RNA or DNA

Answer 3

RNA! they have a mutation every generation

Question 4

what types of mutations can viruses have?

Answer 4

point mutations
deletions
insertions
recombinations and rearrangements
some insert into host genome and can have mutations there

Question 5

give an example of how antigenic variants produce new strains spontaneously over time

Answer 5

antigenic drift of influenza viruses

Antigenic shift of influenza virus causes pandemics

Question 6

what is complementation regarding two viruses in one host?

Answer 6

when the gene function of 1 virus replaces a mutated gene of another
allows the defective viruses to replicate and express their genes

Question 7

what is phenotypic mixing?

Answer 7

exchange of capsid proteins

Question 8

what is a pseudotype

Answer 8

the genetic material of one virus is in the capsid or envelope of another

Question 9

what is reassortment regarding two viruses in 1 host?

Answer 9

the rearrangment of parts of a segmented genome to form a new set of segments
ex. influenza with antigenic shift

Question 10

what is recombination

Answer 10

the exchange of genes by crossing over at regions of homology
produces a hybrid virus that reproduces

Question 11

out of the 5 types of virus interactions when inside a host, which two cause a progeny that is different that its parents?

Answer 11

recombination and reassortment

Question 12

interference and methods that it can occur

Answer 12

infection by one virus tends to prevent infection by another by:
blocking receptors
competition for receptors
production of interferon or other anti-viral agents

Question 13

what disease may be able to be treated with gene therapy?

Answer 13

CF
combined immune deficiency
hemophilia
various enzyme deficiency disorders

Question 14

list 5 ways cancer can be treated with gene therapy

Answer 14

tumor suppressor genes
silencing of oncogenes
immune response genes
toxic or suicide genes
replicating, cytotoxic viruses

Question 15

what is a characteristic that must apply to a virus being used in gene therapy?

Answer 15

requires mutants whose replication is severely restricted

Question 16

list 4 viruses that have been used in gene therapy

Answer 16

retrovirus
adenovirus
herpes simplex virus
adeno-associated virus

Question 17

what are 4 problems associated with gene therapy

Answer 17

short duration of expression
low efficiency of gene transfer
inflammation in response to the virus
potential for chromosomal disturbances by virus

Question 18

What happened to Jesse gelisinger ?

Answer 18

Was trying to use gene therapy

Had bad rxn to the adenovirus vector used, causing acute respiratory distress syndrome. Killed him