HIV/AIDS: 10.31.22. and 11.2.22. Study Questions Flashcards
Draw and label the structure of HIV
Draw and label the steps of an HIV infection (8)
- viral genome and reverse transcriptase enter cell
- DNA copy synthesized by reverse transcriptase
- RNA degraded; second DNA strand synthesized
- DNA either circularizes (unintegrated provirus) or integrase incorporates it into host cell genome (integrated provirus)
- with host cell activation, viral DNA is transcribed, yielding messenger RNAs and viral genome RNA
- viral RNAs are translated yielding viral enzymes (including protease) and structural proteins
- viral membrane proteins are transported to host cell membrane
- final viral assembly and budding takes place
Draw and label the progression of HIV disease indicating culturable viral titer, viral nucleic acid levels and CD4 cell count over time
What is the difference between the terms HIV, AIDS, and HIV disease? and what they all stand for.
HIV: human immunodeficiency virus. the virus that causes AIDS.
HIV disease: infection with HIV resulting in signs/symptoms
AIDS: acquired immunodeficiency syndrome. the end stage of HIV disease.
How is HIV transmitted horizontally? (4)
- heterosxual sx
- homosxual sx (MSM)
- injection drug use (IDU)
- contaminated blood/needles/etc
How is HIV transmitted vertically? (3) what are the percentages?
from mother to infant:
- gestation (5-10%)
- labor and delivery (5-10%)
- brstfeeding (15-20%)
How does HIV enter cells?
membrane fusion
Which cells are targets of HIV?
CD4+ cells: helper T cells, macrophages, monocytes, and dendritic cells
What is the receptor and co-receptor used by HIV?
receptor: CD4 (helper T cells, macrophages, dendritic cells)
co-receptor: CCR5 or CXCR4
Which surface proteins of HIV interact with the receptors?
GP120 (surface protein) and CCR5 (co-receptor)
What is reverse transcriptase?
an enzyme that synthesizes DNA using RNA as a template
Why is reverse transcriptase important in HIV?
makes dsDNA, but mutations are introduced. high mutation rate allows HIV to evolve quickly, altering the antigens and avoiding the immune system.
What is “viral setpoint”?
measure of HIV RNA at the end of the ARS stage. it’s important because it’s a predictor of disease progression.
At what stage does AIDS develop? (aka how much does the CD4 cell count have to be)
when CD4 cell count is under 200 cells/microliter of blood
what is HAART, and what does it stand for ?
highly active antiretroviral therapy (2-3 drug combo.)
what does HAART do that is so important in control of HIV? how does it do it? (3)
it lowers the viral set point by
1. slowing the progression to AIDS
2. decreasing infectiousness
3. decreasing chance of mutation to drug resistance
what are the current targets of anti-HIV drugs? (5)
R.I.P. Carter Flint
1. RT inhibitor
2. Protease inhibitor
3. Fusion inhibitor
4. Integrase inhibitor
5. CCR5 inhibitor
how can horizontal transmission of HIV be prevented?
Behavior change:
- use condms
- fewer partners
Modify biological factors:
circumcison 60% effective
how can vertical transmission of HIV be prevented? (3)
- treating with just one drug (monotherapy) during pregnancy or at L&D
- combining drugs
- eliminate brstfeeding
what simple step prevents vertical HIV transmission by ~20%?
eliminating brst feeding
What is PrEP? what % reduction in transmission risk does it provide?
Pre Exposure Prophylaxis.
- daily pill
- combination of two NRTIs that prevent HIV replication
reduces risk of HIV transmission by 90-99%
What is PEP? what % reduction in transmission risk does it provide? (3)
Post Exposure Prophylaxis.
- taking anti-HIV drugs ASAP after potential exposure
- combination therapy
- initiate within 72 hours of exposure
- 81% risk reduction
What is TasP? what % reduction in transmission risk does it provide?
treatment as prevention. 96-100%
why is TasP important? (2)
- HIV + person can have a kid with an HIV - person and both the partner and the child can remain HIV negative
- treatment is currently the most effective prevention strategy available
