HIV Flashcards
What is HIV?
Single stranded RNA retrovirus that uses the machinery in host CD4 T helper cells to replicate. Once replicated, the viral copies burst through the CD4 membrane, destroying the cell in the process. Billions of T cells are destroyed every day if HIV is not treated adequately.
When HIV continues to replicate
the viral load increases and the CD4 count decreases
AIDS is diagnosed when
CD4 falls below 200cells/mm3 or the patient develops an AIDS defining condition
HIV transmission
Blood, semen, vaginal secretions, rectal secretions, or ingestion of breast milk.
Most infections are caused by unprotected vaginal or rectal sex and sharing injection drug equipment.
Vertical transmission
Mother to child transmission
HIV can spread from woman to child during pregnancy, childbirth, breastfeeding.
Screening of HIV
All patients 13-64 need to be screened at least once.
If a person is high risk, annual screening should be conducted
High risk- sharing drug equipment, high risk sexual behavior, h/o sexually transmitted infections, h/o hepatitis or TB infection.
Acute HIV infection
Presents with non-specific flu like symptoms that can last a few days to several weeks
What happens about 2 weeks after infection?
the viral load is high enough for HIV RNA and HIV p24 antigens to be detected with an initial HIV1/HIV2 antigen/antibody screening test.
What do you do if an HIV antigen/antibody immunoassay is positive?
Confirm with antibody differentiation immunoassay. If positivem HIV confirmed.
If negative, quantify the viral load with an HIV1 nucleic acid test
OTC HIV testing
OraQuick detects the presence of HIV antibodies and provides intermediate results. If positive, it must be followed up with a confirmatory test.
These tests should be used >3 months from exposure due to the lag in antibody production. Testing sooner can cause a false negative result.
HIV replication stages
Stage 1.) Binding/Attachment
Stage 2.) Fusion
Stage 3.) Reverse Transcription
Stage 4.) Integration
Stage 5.) Replication
Stage 6.) Assembly
Stage 7.) Budding and Maturation
HIV Replication Stage 1 (Binding/Attachment)
HIV attaches to a CD4 receptor and the CCR5 and/or CXCR4 coreceptors on the surface of the CD4 host cell.
HIV Replication Stage 1 (Binding/Attachment) Drugs
CCR5 antagonist- maraviroc
Attachment inhibitor- fostemsavir
Post-attachment inhibitor- ibalizumab
HIV Replication Stage 2 (Fusion)
The HIV viral envelope fuses with the CD4 cell membrane. HIV enters the host cell and releases HIV RNA, viral proteins and enzymes needed for replication
HIV Replication Stage 2 (Fusion) Drugs
Fusion inhibitor: enfuvirtide
HIV Replication Stage 3 (Reverse Transcription)
HIV RNA is converted to HIV DNA by reverse transcriptase (an HIV enzyme). HIV DNA can then enter the CD4 cell nucleus
HIV Replication Stage 3 (Reverse Transcription) Drugs
Nucleoside reverse transcriptase inhibitors (NRTIs)- emtricitabine, tenofovir
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)- efavirenz, rilpivirine
HIV Replication Stage 4 (Integration)
Once inside the CD4 cell nucleus, integrase (an HIV enzyme) is released and used to insert HIV DNA into the host cell DNA
HIV Replication Stage 4 (Integration) Drugs
Integrase Strand Transfer Inhibitor (INSTIs)- bictegravir, dolutegravir, raltegravir
HIV Replication Stage 5 (Replication)
Host cell machinery is used to transcribe and translate HIV DNA into HIV RNA and long chain proteins (the HIV building blocks)
HIV Replication Stage 5 (Replication) Drugs
None
HIV Replication Stage 6 (Assembly)
New HIV RNA, proteins, and enzymes (including protease) move to the cell surface and assemble into immature HIV
HIV Replication Stage 6 (Assembly) Drugs
None
HIV Replication Stage 7 (Budding and Maturation)
Immature HIV pushes out of the CD4 cell and protease (an HIV enzyme) breaks up the long viral protein chains, creating mature virus that can infect other cells