Human Retroviruses Flashcards
What are HERVs?
Human endogenous retroviruses (ancient retroviruses that have integrated into germ line cells)
Most are defective and cannot produce virus.
The gag-pol precursor ultimately produces ___________.
integrase and reverse transcriptase
What are LTRs?
Long terminal repeats –pieces of repeat DNA at the ends of HIV genes required for viral splicing and activation of transcriptase
Where (in the cell) does reverse transcriptase act?
In the cytoplasm
Once the ssRNA has been converted to dsDNA, an enzyme shuttles it into the nucleus where it will get spliced into the human genome by integrase.
_________ binds to CD4 (specifically CCR5 and CXCR4).
gp120
What is the most error-prone step of HIV infection?
Reverse transcription
There are three AIDS-defining cancers: ________________.
Kaposi’s sarcoma, cervical cancer, and non-Hodgkin’s lymphoma
____________ cancers are on the rise.
Non-AIDS-defining
The first retrovirus linked to human disease was _______________.
human T-lymphotropic virus
What diseases does HTLV cause?
- Adult T-cell leukemia/lymphoma
- Uveitis
- Myelopathy
Describe the structure of HIV.
It is an enveloped virus with a protein capsid and two separate strands of positive-sense ssRNA.
Describe the process by which HIV infects host cells.
1) gp120 binds to CCR5 and CXCR4 and sticks gp41 into the host cell membrane
2) The lipid envelope dissolves into the host membrane
3) The protein capsid dissolves
4) Reverse transcriptase converts the ssRNA genome of HIV into DNA:RNA
5) Ribonuclease degrades the RNA and replaces it with DNA, leaving DNA:DNA
6) Integrase brings the DNA:DNA HIV into the nucleus and splices it into the host genome
7) Host RNA polymerase II writes viral mRNA to create new virions
HIV pol encodes __________.
protease and integrase
Splicing is only required for one of the HIV gene groups: _____________.
env (meaning gag and pol do not require splicing)
Think about a envelope opener slicing open a letter.
The LTRs contain ________________.
promoter elements