Pathogenesis of HIV Flashcards
what and when is first peak of Sx
- maybe mono Sx
- around week 6-8 - viral spike
what is stable level of CD4
set-point - varies for people
when do constitutionsal Sx occur
CD 500
when do opportunisitic infections begin
CD 200
def. AIDS
- presence of HIV and
2. presence of opp. infection or CD
3 function of CD4
- help activate macrophages
- activate B cells
- activate NK cells
HIV structure
enveloped RNA virus
what is HIV surface protein
gp120
what does gp120 interact with (2)
CD4-r
coreceptor - CCR5 or CXCR4
what cells have receptors that HIV can bind to
CD4+ T -cells, monocytes, macrophages
what happens in people with no CCR5
can’t get HIV
what causes lack of CCR5
32bp mutation - mostly northern europeans
- must be homozygous
what happens in tetanus vaccine in people with HIV
get increased viral load
what dramatically increase HIV load
inflamm. cytokines - IL1, TNF, !L-6
what is special about HIV to give it wide population differences
- high rep. rate (bill/day)
- high error rate
- many mutations - lots of variance
what are 2 main changes to CD4
- less cells
2. defective cells
2 general hypothoses about why kills CD4
- direct killing
2. indirect killing
why does direct killing not explain everything
when look at pool of CD4 cells that die, only small # have infection
what supports indirect hypo
when look at cells ex vivo not infected they are apoping
**3 possible indirect mechs
- immune activation causes proliferation and then apoptosis
- some virus proteins cause activation or cause cells to apoptose
- lipopolysaccharide(LPS) translocating into the blood may cause activation
2 ways CD4 cells are dyfunctional
- can’t prolif to antigens
2. Can’t produce IL-2 to make themselves grow
what does HIV ABs indicate
have disease, but can’t get rid of - same thing in HepC, but in HepB it means you are immune
2 ways to detect HIV
- direct detection
2. detect ABs
4 ways of direct detection
- culture or isolate virus from blood or lymph (expensive)
- detect presence of DNA or RNA in plasma via PCR (standard)
- detect DNA in cells (not standardized)
- detect presence of HIV protein in blood (p24) assay- only good for high levels