HIV 4/1/13 Flashcards
What are the 3 phases of HIV-1 disease progression?
- ) Acute Phase
- ) Asymptomatic latent phase
- ) Symptomatic phase
What occurs during acute phase
Rapid viral replication and dissemination throughout the bod
What occurs during asymptomatic phase?
Virus is brought under control by the immune system
What occurs during symptomatic phase
Immune failure, opportunistic infection, AIDS related cancer
What is the structure of HIV virions?
Spherical, enveloped
If a virion has an envelope, how must it enter the cell?
Must induce a membrane fusion event to dump the nucleocapsid into the cytoplasm.
What kind of genomic material does HIV contain
Two copies of the RNA genome (diploid)
WHat is p24?
A capsid protein that forms the cylindrical core. Used to test for HIV viral load.
Enzymes required for replication?
Reverse transcriptase, Integrase , protease
What are the envelope proteins
Gp120 (receptor binding), Gp41(Membrane fusion)
What are LTRs?
Long terminal repeats….basically promoters for mRNA synthesis and genome replication
What is Tat?
An accessory protein, unique to HIV that drives transcription
What is Rev
Another HIV unique accessory protein, drives mRNA transport out of the nucleus)
What is nef
yeah…accesory protein. contribute to virus pathogenesis….some pts who have HIV but dont progress to aids have nef mutants.
Describe virus attachment
- Gp120 binds CD4
- Gp 120 binds chemokine coreceptor
- This activates Gp41 (the fusion protein)
- Gp 41 promotes fusion and entry
What happens after entry
- RNA converted to DNA by reverse transcriptase
2. Integrase inserts a HIV DNA intertmediate into the host chromosome (this is now called a provirus)
HIV integration does not require——-
Cell division
Again, what does REV do?
Allows transport of unspliced RNA out of nucleus
How are virus particles released?
Budding…
What do protease inhibitors do?
Inhibit protease which is responsible for the cleavage of core proteins.
What drug can you use to drop the rate of prinatal transmission to 1%?
ZDV (AZT)
What level of T cell population signifies a shift from the chronic to symptomatic phase>
CD4 T cell below 200
The higher the viral load, the faster the progression of the disease
True
What is the typical survival rate once HIV infection has been diagnosed?
about 2 years with no anti-retroviral drug treatment
What is a “long-term survivor”?
Survivors still alive after 10 years
What is an elite controller?
These pts remain symptom free, maintain low plasma virus levels and have normal CD4 counts without therapy after 10-15 years of infection