HIV Flashcards
gag
core and matrix proteins; p24
env
membrane glycoproteins: gp120 (outer) and gp41 (transmembrane)
pol
Reverse transcriptase, protease, and integrase
tat
Positive regulator of transcription
rev
Allows export of transcripts from the nucleus
vif
Affects particle infectivity
vpr
Viral protein R. Transport of DNA to nucleus. Augments virion production. Cell cycle arrest.
vpu
Viral protein U. Promotes intracellular degradation of CD4 and enhances release of virus from cell membrane.
nef
Augments viral replication. Down-regulates CD4 and MHCH
What is the major co-receptor for macrophage-tropic strains of HIV?
CCr5
What is the major co-receptor for T cell-tropic strains of HIV?
CXCr4
Most common strain of HIV in U.S.
HIV-1 Group M Subtype B
Properties of Stage I HIV
Acute retroviral syndrome – highly contagious
30% of patients asymptomatic; others have flu-like symptoms
- Primary infection of blood, mucosal cells
- Infection established in lymphoid tissues
- Acute HIV syndrome, spread throughout body
- Immune response
Properties of Stage II HIV
Clinical latency
Establishment of chronic infection; virus trapped in lymphoid tissues by follicular dendritic cells
Low-level viral replication for several years
Properties of Stage III HIV
AIDS
Destruction of lymphoid tissue
Defining opportunistic illnesses
Stage 3-Defining Opportunistic Illnesses in HIV infection
Kaposi sarcoma Candidiasis CMV Cryptococcus Herpes simplex Lymphoma Pneumonia
Steps of HIV replication
- Virus binds with CD4 on T cell surface via gp120
- Binding induces conformational change that opens up site for co-receptor binding (CCr5: T cell / CXCr4: Macrophage)
- HIV RNA, protease, integrase, and reverse transcriptase enter cell
- Viral DNA is formed by reverse transcriptase in cytoplasm, then transported across nucleus via protein R, and integrated into host DNA via integrase –> now a provirus
- New viral RNA is formed from host+viral DNA
- New RNA transported out of nucleus via tat and and rev
- New RNA is used to make viral proteins
- New RNA and proteins move to cell surface and a new, immature HIV forms
- New virus/proteins mature via protease, are exocytosed
What is significant about CXCr4?
Only present on T-cells (CCr5 present on T cells and macrophages). Indicate faster/more severe illness because they provide a second method of entry into host cell.
