HIV I Flashcards
64% of new HIV infections every year occur in ___.
64% of new HIV infections every year occur in Sub-Saharan Africa
~70% of new infections of HIV in the US in 2016 were attributed to ___.
~70% of new infections of HIV in the US in 2016 were attributed to male-male sexual contact.
The highest single-exposure risk for contracting HIV is contact via ___. The second is contact via ___.
The highest single-exposure risk for contracting HIV is contact via blood transfusion. The second is contact via vertical transfer (mother to child).
The primary viral factor which affects transmission is ___.
The primary viral factor which affects transmission is the level of virus in the HIV infected individual
Host factors which affect transmission
- Complicating additional STIs (which may cause ulceration or otherwise local susceptibillity to infection)
- Type of sexual behavior (anal sex risk > vaginal sex risk > oral sex risk)
- Gender of sexual partners (highest risk M to M, lowest risk W to W)
- CCR5 variants of individuals involved
Most often, the transmitted HIV is . . .
Most often, the transmitted HIV is macrophage-tropic HIV (also known as R5 HIV) and this virus preferentially utilizes the CCR5 co-receptor, not the CXCR4 receptor
When is antiretroviral post-exposure prophylaxis most effective?
Within the first few days of infection, before HIV has a chance to multiply locally
Pathway of HIV infection and dissemination

HIV serology studies

Symptoms of the early viremic phase of HIV
- malaise,
- fever,
- rash,
- lymphadenopathy,
- oral ulcers,
- diarrhea
Acute phase of HIV infection is defined as . . .
. . . the time between the appearance of HIV RNA and before HIV infection is detectable by immunoassays, lasts between 5 and 40 days after RNA appears. Duration depends on s on the generation of immunoassay used for testing
Generations of HIV detection
- 1st generation: HIV IgG, high level, earliest ~50 days
- 2nd generation: HIV IgG, low levels, earliest ~35 days
- 3rd generation: HIV IgM, low levels, earliest ~22 days
- 4th generation: HIV-1 p24 antigen, earliest ~15 days
- Nucleic acid tests: HIV-1 RNA, earliest ~10 days
Recommended HIV testing algorithm

HIV “window” period
when virus is present in the blood, but seroconversion has not yet occurred
It is very difficult to diagnose HIV before ___-post infection. If tests come back negative but HIV is still suspected, ___.
It is very difficult to diagnose HIV before 15 days-post infection. If tests come back negative but HIV is still suspected, order a serum HIV RNA assay now and have the patient come back in a few days for another protein assay.
Natural progression of HIV

Acute HIV infection may be generally characterized by . . .
Acute HIV infection may be generally characterized by a mononucleosis like illness that occurs within weeks after infection
Untreated individuals with low viral “set points” progress ___, while untreated individuals with high viral “set points” progress ___.
Untreated individuals with low viral “set points” progress more slowly, while untreated individuals with high viral “set points” progress more rapidly.
As the level of CD4+ T cells drops below ___, individuals are at increased risk for opportunistic infections.
As the level of CD4+ T cells drops below 500, individuals are at increased risk for opportunistic infections.
Gut mucosal CD4 T cells in HIV
Acute infection is associated with massive depletion of mucosal CD4+ T cells that are typically enriched with cells co-expressing CCR5. This gut mucosal CD4+ T cell depletion can lead to infection and inflammation of the entire bowel.
Ways in which HIV chronically stimulates the immune system to create CCR5 fodder
- Direct effects of HIV as a ligand for toll like receptors on plasmacytoid dendritic cells leading to production of interferon-α
- microbial translocation across the gut and activation of TLR4 leading to the production of pro-inflammatory cytokines
- co-infection with viruses (eg CMV) leading to CMV specific T cell activation
- reduced ratio of Thelper-17 and regulatory T cells, especially in the gastrointestinal tract
Major groups of antiretrovirals for HIV
- HIV protease inhibitors
- Reverse transcriptase inhibitors
- Integrase inhibitors
- Entry inhibitors
Cobicistat
Inhibits the hepatic p450 enzyme which metabolizes many antiretrovirals
Drug-resistance in HIV. . .
. . . develops rapidly when a single antiretroviral is used



