what are the 2 types of HIV? where are they prevalent?
HIV1: US, worldwide
HIV2: western africa, southern asia
–> HIV2 so uncommon that HIV usually refers to HIV1
which type of cells does HIV target?
CD4+ cells (T-helper, but also macrophages/dendritic cells)
which protein does HIV target?
CD4
which protein on the HIV envelope binds to CD4?
gp120
how does HIV enter the cell? which receptors/co-receptors are involved?
the molecule gp120 on surface of HIV binds to CD4. needs co-receptor CXCR4 or CCR5 to enter
CXCR4: on t cells
CCR5: on t cells, macrophages, dendritic cells
which cells contain the co-receptor CXCR4?
t cells
which cells contain the co-receptor CCR5?
t cells, macrophages, dendritic cells
people with which mutation are immune to hiv?
mutation of CCR5
what kind of virus is HIV?
single strand RNA retrovirus
how does a ‘single strand RNA retrovirus’ replicate inside host cells?
- it uses reserve transcriptase to make a complimentary piece of genetic material -> DS proviral DNA
- this DNA gets incoorporated into the host cell DNA
–> virus particles are made
how is HIV spread?
sexual intercourse
what happens during acute infection of HIV on cellular level?
(start with R5 strain binding to CCR5)
R5 strain of HIV binds to CCR5 coreceptor -> virus inside t cells/macrophages/dendritic cells -> dendritic cells move to lymph nodes -> many more immune cells infected locally -> big spike in HIV in blood
how are different strains of HIV made?
errors during replication (still HIV, but targets different cell types = ‘viral tropism’)
what are the symptoms of acute HIV infection?
flu-like symptoms
acute infection: HIV in blood high or low?
high
acute infection: HIV in blood is high. what happens next?
counterattack of immune system -> HIV in blood lowers to stable lower level (and enters chronic phase)
after how long is the chronic phase reached after acute infection?
12 weeks
how long can the chronic phase be?
why is this?
2-10 yrs
the virus is slowly replicating and t cells are slowly decreasing
body can stil fight off infection relatively well
how many t cells are still enough to sustain the chronic phase? (without severe infections)
> 500 t-cells/mm3
t-cells between 200-500/mm3 -> which symptoms? hiv or aids?
still hiv
- lymfeadenopathy
- oral candidiasis
- hairy leukoplakia (white patch on tongue due to EBV)
t-cells <200/mm3 -> hiv or aids? symptoms?
aids (immune system severely compromised)
- persistant fever, fatigue, weight loss, diarrhea
- aids-defining conditions
what are ‘aids-defining’ conditions?
- recurrent bacterial pneumonia
- pneumocystis pneumonia (fungus)
- fungal infections (candidiasis of esophagus)
- tumors (Kaposi, primary lymphoma brain)
what are the modes of transmission of HIV?
- sexual intercourse (male to male in US, male to female in developing countries)
- iv drug use
- mother to child (placenta, delivery, breast milk)
less common:
- accidental needle sticks, blood products
how to diagnose hiv?
Blood:
- antibody test
- antibody/antigen test (recommended)
- RNA/DNA test (= NAT test; nucleic acid test)
