HRR: HIV/AIDS Flashcards
HIV infects which cells?
CD4+ T cells
Describe the envelope of HIV.
Has receptors that bind CD4 on T cells and kills them
What does the pol gene encode for?
Protease, reverse transcriptase, integrase
Which gene is the most targeted for treatment in HIV?
Pol! Mostly for reverse transcriptase
What does the gag gene encode for?
Matrix, capsid, nucleocapsid, budding protein
What may be associated with acute HIV infection?
Flu-like symptoms, thrush, maculopapular rash
HIV uses which cells to replicate?
CD4 T cells
Describe HIV lifecycle.
- Envelope binds CD4 receptor on T cell
- Conformational shift allows a co-receptor to bind, allowing HIV to fuse with the T cell membrane
- Reverse transcriptase uses viral RNA to make viral DNA
- DNA translocates to the nucleus and integrates into the DNA
- DNA gets transcripted/translated
- Viral core buds and releases from the cell
How does HIV impact immune defense?
Impairs them via attack and depletion of CD4 T cells
What kind of infection does HIV put you at risk for?
Opportunistic infection due to CD4 depletion
What is the clinical course of HIV?
It is a long process. Primary infection occurs, and CD4 count will begin to go down over the course of 6-8 weeks. There is then a slow, progressive decline in CD4 count over the course of 5-6 years, as viral load slowly increases. After a number of years where viral load outweighs CD4 count, the latent period is over and you’re more prone to opportunistic infection.
How do we test for HIV?
- Screening using combination immunoassay
- Confirmation via differentiation immunoassay looking for HIV 1 or 2 antibodies
- Viral DNA detection via nucleic acid testing
What defines a false positive HIV test?
Positive screening with negative antibodies and nucleic acid
What are risk factors for HIV?
Sex with an infected person, sex with someone of unknown HIV status, occupational risk, needle sharing
What are the goals of antiretroviral therapy?
Decrease HIV RNA, increase CD4, prevent transmission, improve quality of life
Describe pneumocystis pneumonia in relation to HIV.
Opportunistic infection that becomes a risk once CD4 drops below 200. Super common and caused by pneumocystis jirovecii
Describe cryptococcus neoformans in HIV.
Encapsulated fungus that enters via respiratory route and may cause pneumonia or meningitis
Describe toxoplasma in HIV.
Opportunistic infection with risk after CD4 is less than 100. Contracted by ingestion of cysts and shows ring-enhancing lesions in the brain or ocular toxoplasmosis
CNS toxoplasmosis can be difficult to distinguish from…
CNS lymphoma
What is CMV retinitis?
Opportunistic infection becoming a risk following CD4 count under 50. May cause blindness
Describe shingles (herpes zoster) in HIV.
Can occur at any CD4 count and tends to be common in HIV patients. May progress to disseminated disease in AIDS or severe immunosuppression in HIV
Describe Kaposi sarcoma in HIV.
Associated with AIDS. Dark red splotchy lesions
Describe progressive multifocal leukoencephalopathy in HIV.
Heavily associated with AIDS or longstanding HIV, caused by JC virus, and shows signs of encephalopathy.
Describe TB in HIV.
Seen in any CD4 count, but being more immunodeficient may increase risk for disseminated disease.
