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What does HIV and AIDS stand for?
- HIV (Human Immunodeficiency virus)
- AIDS (acquired immunodeficiency syndrome)
What is the HIV and what does it contain?
- An RNA retrovirus - subfamily Lentivirus
- Contains 2 copies of RNA
- Enzymes: Reverse transcriptase
- Two major envelope proteins: GP120 (docking)
- GP41 (transmembrane)
Requires host DNA to replicate and produce proteins
What are the types of HIV and what are there properties?
- Types HIV 1 HIV 2
- virulence High Low
- infectivity High Low
- prevalence Most common Uncommon, found in
- globally West Africa
- binding site CCR5 CXCR4 co-receptor
Common HIV host cell and why?
- CD4 T cells are most commonly infected. High affinity for gp120.
- Acute phase death - cytopathic damage by virus
- Chronic death - chronic activation of T cells
- inhibition of thymic output of T cells
- suppression of the bone marrow
- destruction of lymph-node architecture
- low-level ongoing infection of memory CD4 T cells
What are the methods of transmission?
Sexual - anal, vigina (homo=men, hetro=women (most common))
Percutaneous - rarely transfusions, needle sharing, needle stick
Vertical - transplacental, periparium, breast milk ingestion
What are the stages associated with HIV infection?
Stage 1 - Primary - cold or flu-like symptoms. Antibody test usualy negative, becomes positive after 3-6months (6m = 95%) seroconversion.
Stage 2 - Asymptomatic - average duration 10 years. Symptom free, may have swollen glands.
Stage 3 - Symptomatic - immune system deteriorates. CD4 count below 500 = risk of opportunistic infections.
Stage 4 - HIV to AIDS. Advanced HIV when CD4 count below 200. Need AIDS defining illness or infection.
What tests are available for HIV testing?
- Screening tests - ELISA or EIA - rapid testing - whole blood, plasma, saliva or urine test.
- Confirmatory tests - Western Blot analysis, RT-PCR)
Rapid HIV antibody test - sensitive and specific 99%. Results on 5 to 40 minutes
HIV viral load - first choice for diagnosing acute HIV
HIV p24 antigen - first antigen to be elevated in acute HIV. Can be used for acute diagnosis
What classes of drug are available to reduce the progression of HIV?
- RTI - Reverse-Transcriptase Inhibitors
- PI - Protease Inhibitors
- Integrase Inhibitors
- Entry (fusion) Inhibitors
- Maturation Inhibitors (new class)
What are the three forms of RTI?
- - NARTI or NRTI - Nucleoside analogue reverse-transcriptase inhibitors.
- - NtARTI or NtRTI - Nucleotide analogue reverse-transcriptase inhibitors
- - NNRTI Non-nucleoside reverse-transcriptase inhibitors
What are the main reasons for HAART?
- Highly active antiretroviral therapy is used to:
- reduce the toxic effects of the drugs,
- to increase the time it takes for resistance to occur,
- restore sensitivity in some cases,
- slow the progression of the disease,
- fewer opportunistic infections,
- improve or stabilise immunity,
- suppress HIV replication.
What is a typical combination therapy?
NNRTI OR PI OR Integrase Inhibitor
AND 2 NRTIs