HIV Virology

Question 1

How does HIV infect Tcells, macrophages, and DCs?

Answer 1

HIV’s envelope protein gp120 binds to CD4 and CCR5, causing a confirmational change in the gp120 protein

–> the confirmational change brings the viral envelope closer to the cell membrane, allowing gp41 to penetrate the cell membrane and fuse the virus with the cell

–> Viral RNA, proteins and Pol enzymes are released into the cell

Question 2

What anatomical areas are most at risk of an HIV infection that makes it sexually transmittable?

Answer 2

Vaginal mucosa and Cervical epithelium

Anal and rectal mucosa
–> high volume of CD4+ cells

Foreskin is rich in CD4+ T cells

Question 3

How does HIV replicate?

Answer 3

1. Fusion of HIV ro the host cell surface (by binding of gp120 to CD4 and CCR5 or CXCR4)
2. HIV RNA, reverse transcriptase, integrase, and other viral proteins enter the host cell
3. Viral DNA is formed by reverse transcriptase in the cytoplasm
4. Viral DNA is transported across teh nucleus and integrates into the host DNA by integrase
5. New viral RNA is used as genomic RNA and to make viral proteins
6. New viral RNA and proteins move to the cell surface and a new, immature, HIV forms
7. The virus matures by protease releasing individual HIV proteins

Question 4

What is HIV Vpr?

Answer 4

Vpr functions in the early steps of the HIV-1 life cycle

It regulates p53 induced transcription and apoptotic pathways

Question 5

What is HIV LTR?

Answer 5

A promotor protein that drives transcription of HIV proteins

Question 6

What is the HIV TAT protein?

Answer 6

Protein that increases the level of transcription of HIV dsDNA

Binds to the TAR binding domain and starts transcription process

Question 7

What is the HIV Rev protein?

Answer 7

Binds to the REV response element on mRNA so that the mRNA can be taken out of the nucleus

–> without rev, the mRNA is quickly spliced by host regulatory proteins

Question 8

What is the HIV Nef protein?

Answer 8

Induces several processes that contribute to HIV infectivity and replication:

1. Enhanced replication
2. T-cell activation
3. Internalization
4. Actin remodeling
5. Increased cholesterol incorporation
6. Stimulation of viral spreading

Question 9

What is the HIV Vpu protein?

Answer 9

Viral Protein Unique (Vpu)

–> Function is to:

1. Induce degredation of CD4 proteins on cell surface
2. Enhance release of newly formed virions

Question 10

What is the course of HIV infection?

Answer 10

Question 11

What are the possible HIV diagnostic assays?