Retroviruses Flashcards
How long are cis-activating retroviruses latency periods
weeks-months(intermediate)
What has to happens when a virus infects a host cell
Partial uncoating of its surface triggers reverse transcriptase to transcribe RNA into DNA
What is the cellular oncogene activated by in cis-activating retroviruses
provirus
Bovine leukemia virus is caused by what type of retrovirus
Trans-activating
What are some characteristics of lentivirus
- Persistent/latent infection 2. Cytopathic 3. All infect macrophage 4. All have tat and rev
How are retroviruses transmitted
Horizontal (blood, saliva, etc) vertical (embryo)
How efficient are cis-activating retroviruses
high-intermediate
How long is the latency period in trans-activating retroviruses
months-years(long)
What is a transducing retrovirus
cell derived oncogene carried in viral genome
What does the pro gene encode
protease
What are 2 major issues with current drugs dealing with retroviruses
- Can’t target latent infected cells 2. Drugs can’t cross blood brain barrier
How efficient are trans-activating retroviruses
very low efficency
What three things do tax and tat do
- Activate gene expression directed by the long terminal repeat 2. Enhance viral gene expression 3. Enhance viral replication
What are characteristics of transduced oncogenes
- Truncated 2. Point mutations 3. fused with viral sequences 4. Under control of viral promoter
how long are transducing retroviruses latency periods
days (short)
What are characteristics of cytopathic virus-host interaction
1 Extensive virus replication 2 direct toxicity 3 immune system-mediated killing of infected cells
What does the prt gene encode
virion protease
What is required for virus DNA integration into the host genome
long terminal repeat
What do Rex and Rev do
switch from early (tax, rex_ to the late (gag, prt, pol, env) gene expressions
What does env gene encode
Envelope
What are proviruses
dsDNA that intergrates into host DNA and becomes part of its genome
What does pol gene encode
RT and integrase
What are 4 reasons antiviral therapy is complicated
- 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
What is the order from 5’ to 3’ for retrovirus genes
gag-pro-pol-env
How efficient are transducing retroviruses
100% in animals (high)
What do long terminal repeats have on DNA transcrips
Viral promoter, Transcription, initiation, and termination sites
What does the gag gene encode
3 internal structures
What doe viruses use to transcribe ssRNA into dsDNA
reverse transcriptase
What does the 5’ and 3’ RNA genome have
unique sequences and repeat sequences
What are characteristics of non-cytopathic virus-host interaction
1 Permanently produce virus at low level 2. Dormant virus 3. Transform cells, results in malignancy
