Retroviruses

Question 1

How long are cis-activating retroviruses latency periods

Answer 1

weeks-months(intermediate)

Question 2

What has to happens when a virus infects a host cell

Answer 2

Partial uncoating of its surface triggers reverse transcriptase to transcribe RNA into DNA

Question 3

What is the cellular oncogene activated by in cis-activating retroviruses

Answer 3

provirus

Question 4

Bovine leukemia virus is caused by what type of retrovirus

Answer 4

Trans-activating

Question 5

What are some characteristics of lentivirus

Answer 5

1. Persistent/latent infection 2. Cytopathic 3. All infect macrophage 4. All have tat and rev

Question 6

How are retroviruses transmitted

Answer 6

Horizontal (blood, saliva, etc) vertical (embryo)

Question 7

How efficient are cis-activating retroviruses

Answer 7

high-intermediate

Question 8

How long is the latency period in trans-activating retroviruses

Answer 8

months-years(long)

Question 9

What is a transducing retrovirus

Answer 9

cell derived oncogene carried in viral genome

Question 10

What does the pro gene encode

Answer 10

protease

Question 11

What are 2 major issues with current drugs dealing with retroviruses

Answer 11

1. Can’t target latent infected cells 2. Drugs can’t cross blood brain barrier

Question 12

How efficient are trans-activating retroviruses

Answer 12

very low efficency

Question 13

What three things do tax and tat do

Answer 13

1. Activate gene expression directed by the long terminal repeat 2. Enhance viral gene expression 3. Enhance viral replication

Question 14

What are characteristics of transduced oncogenes

Answer 14

1. Truncated 2. Point mutations 3. fused with viral sequences 4. Under control of viral promoter

Question 15

how long are transducing retroviruses latency periods

Answer 15

days (short)

Question 16

What are characteristics of cytopathic virus-host interaction

Answer 16

1 Extensive virus replication 2 direct toxicity 3 immune system-mediated killing of infected cells

Question 17

What does the prt gene encode

Answer 17

virion protease

Question 18

What is required for virus DNA integration into the host genome

Answer 18

long terminal repeat

Question 19

What do Rex and Rev do

Answer 19

switch from early (tax, rex_ to the late (gag, prt, pol, env) gene expressions

Question 20

What does env gene encode

Answer 20

Envelope

Question 21

What are proviruses

Answer 21

dsDNA that intergrates into host DNA and becomes part of its genome

Question 22

What does pol gene encode

Answer 22

RT and integrase

Question 23

What are 4 reasons antiviral therapy is complicated

Answer 23

1. Retro-viral genome incorporated into host genome 2. Genome may remain dormant for long periods 3. Antigenic variation and drug resistant 4. virus infects cells in immune system

Question 24

What is the order from 5’ to 3’ for retrovirus genes

Answer 24

gag-pro-pol-env

Question 25

How efficient are transducing retroviruses

Answer 25

100% in animals (high)

Question 26

What do long terminal repeats have on DNA transcrips

Answer 26

Viral promoter, Transcription, initiation, and termination sites

Question 27

What does the gag gene encode

Answer 27

3 internal structures

Question 28

What doe viruses use to transcribe ssRNA into dsDNA

Answer 28

reverse transcriptase

Question 29

What does the 5' and 3' RNA genome have

Answer 29

unique sequences and repeat sequences

Question 30

What are characteristics of non-cytopathic virus-host interaction

Answer 30

1 Permanently produce virus at low level 2. Dormant virus 3. Transform cells, results in malignancy