Flashcards in HIV Case Deck (50):
How long can the latency period last in HIV?
up to 10 years
When do symptoms of HIV begin to appear?
when enough CD4 T cells have been destroyed
What are the ways hIV can be transmitted?
exposure to infected blood products
use of contaminated clotting factors by hemophliacs
sharing contaminated needs
transplantation of infected organs
Describe the primary HIV Syndrome. WHen does it occur?
It's a flu-like illness occuring 6-12 weeks after infections
How many months does it take after hte primary HIV syndrome for the HIV antibody test to be positive? What's this called?
How can primary HIV syndrome be diagnosed n?them
viral load titer assay
What's the normal CD4 count? Below what level do people become at risk for opportunistic infections?
below 500 they start to get opportunistic infections
What diseases are predictive of the progression to AIDS?
persistent shingels infecitons
oral hairy leukoplakia
A CD4 count below what maes a person considered to have advanced HIV or AIDS?
What infections are people at risk for under CD4 of 200?
pneumocystis carinii pneumonia
If CD4 is below 50, what are they at risk for?
THe first antibodies that appear are to what viral proteins?
p24 and p55
(then p51, p120 and gp41)
What screening test do we use for HIV?
ELISA serology test
Why do we have to follow-up a positive ELISA?
it's sensitive but no specific
What's the confirmation test of choice?
HOw many bands are required for the diagnosis on western blot?
3 or more
RIsk of dying in three years after diagnosis is linked to what 5 indicators?
CD4 count below 200
viral load over 100,000
older than 50
injection drug user
having prior AIDs-defining illness
At this point in history, what percentage of HIV patients are alive 10 years post diagnosis?
now considered a chronic disease
What are the CDC's HIV screening guildelines?
routine HIV testing to all peopl 13-64 years of age at least once regardless of risk, with repeat testing annually for persons with risk factros
What's the most common opportunistic infection in HIV?
pneumocystis jiroveci (carinii)
How do you diagnose a pneumocystic jirovecci infection?
sputum silver stain
What are the classic symptoms of pneumocystis?
SOB, dry cough, fever
What sort of pneumonia is pnemocystis?
What is HIV's genomic organization?
two copies of +ssRNA
What's the capsid symmetry?
Does it have an envelope?
What are the two main glycoproteins that pierce through the envelop?
gp120 and gp41
What is the trophism for HIV?
CD4+ cells - usually T cells, but also CD4+ monocytes and macrophages
What are the three functional viral enzymes present wihtin the virus capsule that can become active as soon as the virus penertrates the host cells?
reverse transcriptase, protease and integrase
How does HIV gain entry into the host cell?
Two interactions occur: gp120 interacts with CD4 and then the gp41 interacts with either CXCR4 or CCR5
Mutation of which protein leads to immunity to HIV?
CXCR4 can also bind what other molecule? What does this do in terms of HIV infection?
stromal derived factor 1 (SDF-1)
If inhibits HIV transmission
What does reverse trasncriptase do when the HIV gets inside the host cell?
It acts as an RNA-dependent DNA polymerase to creates a molecule of ssDNA from the ssRNA template
Then it acts as a DNA-dependent DNA polymerase to create the dsDNA
What happens to the newly synthesized dsDNA?
it gets integrated into the host genome by integrase
what do we call the virus once it's itnegrated into the genome?
What polymerase is used to replicate the viral genome once it's a provirus?
host RNA polymerase II
What are the two reasons HIV wants to replicate it's genome?
1. you need to reprogram the cell so that the cell will use it's transcription apparatus to suit HIV's needs
2. You need to get the viral enzymes and viral genome copies necessary to make more viral particles
Describe how HIV's genome is organized differently from ours
It differs mostly in its efficiency
It's small, so it uses all three reading frames to code for its genes
What are the three genes we need to know?
gag, pol and env
what does gag encode for?
what's the most important capsid protein and why?
p24, because we can use it for a diagnostic test
what does pol encode for?
the enzymes: reverse transcriptase, protease and integrase
what does env encode for?
the envelope proteins: gp120 and gp41
What are the two functions for the 3' and 5' LTRs on the HIV genome?
1. they act as integration sites for integrase
2. they are strong promoters for transcription factors in the host like NFkB, Sp1 and TBP
What are Tat and Rev and how do their functions differ? Which is active first?
they are virally encoded transcription factors
Tat is active first, then Rev
Tat promotes the early pattern of gene expression = spliced RNA so you get the enzymes needed for establishing the infection in the host cell
Rev is later and it promotes both spliced and unspliced RNA, which is used as the genomes for new viral particles
What happens to viral load after that first viremia spike? Why?
It drops down a bit and then only gradually increases for a while during clinical latency
because at that point you still have functional CD4 cells to work against it
What's the first antigen detectable in an HIV infection?
What can we detect a few weeks after p24?
antibodies against p24
What antibody comes after p24?