HIV/AIDS Lecture #1 Flashcards
(43 cards)
What is the pathogenesis of HIV infection?
glycoprotein 120 (gp120) (on surface of HIV virus) binds to CD4 receptors on T cells, macrophages, and dendritic cells
primary target cell of HIV is the CD4 T helper/inducer lymphocyte
infected CD4 cells are impaired from normal functions, and used for viral replication
ultimately destroyed by a cytolytic effect
What is the impact of HIV infection on the human immune system?
the CD4 T helper/inducer lymphocyte is a key component of cell-mediated immunity
responsible for protecting against viruses, intracellular bacteria, and certain cancers –> weakened immune system, body highly susceptible to infections
infected CD4 cells are impaired from normal functions, and used for viral replication
What are the three routes of transmission of HIV?
- exposure of mucous membrane or damaged tissue to infected body fluids
- blood stream exposure to infected body fluids (blood, semen, pre-seminal fluid, rectal fluid, vaginal secretions, breast milk)
- mother-to-child
What is HIV NOT found in?
urine, feces, sweat, or tears
What is mucous membrane transmission?
sexual transmission most common - receptive anal intercourse carries more risk than insertive anal > receptive vaginal > insertive vaginal > penile-oral fallatio
increased risk of transmission: high viral load of infected partner, presence of an STI, tearing/abrasions, menstruation
What is blood stream method of transmission?
from injection drug use
other methods are rare: blood transfusion, receipt of tissue/organ transplant, tattooing with shared needles, occupational exposure
What are the screening recommendations for HIV?
pts aged 13-64 in any healthcare setting (repeat annually in high-risk groups)
all pregnant women as early as possible (consider repeat test in 3rd trimester)
all pts initiating treatment for tuberculosis
all pts attending STD clinics
testing should be opt-out
What are the methods of HIV diagnosis?
viral detection - nucleic acid test (earliest we can test, at 10 days)
viral detection - 4th generation immunoassay (detects biomarker P24 antigen for acute HIV infection)
antibody detection - 3rd generation immunoassay
antibody detection - 2nd generation immunoassay
antibody detection - 1st generation immunoassay
higher generation of test –> shorter seroconversion window
What is used for the diagnosis of HIV?
positive results from multitest algorithm
positive virologic test: viral load, qualitative HIV NAT - A qualitative HIV NAT (Nucleic Acid Test) is a type of test that detects the presence of HIV RNA (genetic material of the virus) in a person’s blood.
HIV-1/2 antigen/antibody immunoassay - negative
negative for HIV-1 and HIV-2 antibodies and P24 Ag
HIV-1/2 antigen/antibody immunoassay - positive
confirm results with separate test
HIV-1 + and HIV-2 -
HIV-1 antibodies detected
HIV-1 - and HIV-2 +
HIV-2 antibodies detected
HIV-1 + and HIV-2 +
HIV antibodies detected
HIV-1 - or indeterminate and HIV-2 - or indeterminate
HIV-1 NAT –> now look for HIV RNA
HIV-1 NAT+: acute HIV-1 infection
HIV-1 NAT-: negative for HIV-1
What is an at-home HIV test?
rapid testing: results available in 1-30 min
seroconversion window is 3mo, can’t tell what’s happened in the most recent 3 mo
ex. oraquick in-home test using oral fluid
What is OTC rapid test counseling?
patient with reactive results: need to get confirmatory testing
non-reactive results: counsel on seroconversion window (3mo); repeat test if risk event occurred within window period; counsel on methods of risk reduction/prevention
What are the 2 surrogate markers used in assessing the progression of a patient’s infection and effectivness of their antiretroviral regimen?
CD4 T lymphocyte cell count
HIV RNA PCR (viral load)
What is the CD4 T lymphocyte cell count?
primary marker of immunocompetence
most useful before initiation of therapy
lower levels indicative of a more compromised immune system
What is the HIV RNA PCR (viral load)?
used to assess the effectiveness of therapy
most useful after initiation of therapy
higher baseline levels are predictive of faster disease progression
What is disease staging?
stage 0: acute HIV infection in previous 6mo
stage 1: CD4 count >/=500
stage 2: CD4 count 200-499
stage 3 (AIDS): CD4 count <200 or OI diagnosis
What is the difference between HIV infection and AIDS?
HIV: A virus that attacks and weakens the immune system, specifically CD4+ T cells.
AIDS: The final and most severe stage of HIV infection; CD4+ T cell count drops below 200 cells/mm³, or the person develops AIDS-defining illnesses
What is the MOA of nucleos(t)ide reverse transcriptase inhibitors?
synthetic purine and pyrimidine analogues which result in elongation termination of growing proviral DNA chain b/c they lack a 3’OH end
What are the adverse effects of nucleos(t)ide reverse transcriptase inhibitors?
mitochondrial toxicity and lactic acidosis!!
with or without hepatomegaly and hepatic steatosis
seen less with tenofovir, emtricitabine, abacavir, lamivudine
dose adjusted in renal insufficiency (except abacavir)
