Lecture 5- Retroviruses, AIDS, Tumor Viruses Flashcards
HIV appears to have evolved from… and spread through the rest of the world through an increasingly mobile population and aberrant sexual behaviors
simian virus in africa
SIV–>HIV2–>HIV1 ~1930s
A unique feature of retroviruses is that they have an… even though they are an RNA virus
DNA intermediate
Many retroviruses are… but other have significant pathogenicity causing disease and cancer
benign
Retroviruses are… in vertebraes
ubiquitous
Spumaviruses do not cause… and they make … structures inside cell
human disease
“foamy”
2 subfamilies of retroviridae
orthoretroviridae
spumaviridae
The genome of retroviridae is…. and it is also … which is unique
(+)ssRNA
diploid (has 2 identical copies of its genome in the cell)
Are retroviridae viruses enveloped?
yes
What proteins do retroviridae viruses have?
- reverse transcriptase unique
- integrase
- protease
Historically, retroviruses were characterized by … and…
nucelocapsid structure and location in the particle
Retroviruses are now classified as either… or…
simple or complex
Simple retroviruses only encode for…. and complex includes others besides these
Gag, Pro, Pol, Env genes
Retroviruses are able to execute… at the cellular surface and do not require…
- membrane fusion
- receptor mediated endocytosis
The main 2 steps in the replication cycle of a retrovirus is…. which is when… is made into… and then…. which is when the virus dsDNA integrates into host making provirus
- reverse transcription
- ssRNA–>dsDNA
… is a defining feature of retroviruses and it initiates once nucleocapsid is in…
Need higher levels of…
Low levels of… prevent reverse transcription
- cytoplasm
- NTPs
Reverse transcription is …. between genome copies so it is … when copies are identical and there are many different … when different genomes are in the virion
- promiscuous
- silent
- recombinations
Integration of virus DNA is…
permanent
If integration is into the germ-line then provirus is… and is called…
- inherited
- endogenous
Integration may disrupt host genes causing diseases such as
cancer
Integration identified oncogenes (4)
- transcription factors
- secreted growth factors
- growth factor receptors
- cell signal transduction pathways
In retrovirus replication, it is commong to have … viruses made during replication. These are viruses that are missing at least one of gag, pol or env
defective
Defective retroviruses require… to make progeny
complementary infection