Session 8-Blood Borne Viruses:HIV Flashcards
What does HIV stand for?
Human immunodeficiency virus
Why is HIV a retrovirus?
ssRNA -> DNA -> ssRNA
Which cells does HIV infect?
Cells with CD4 surface receptor
True or false: HIV replicates inside cells
TRUE
How is HIV transmitted?
Contact of infected bodily fluids with mucosal tissue/blood/broken skin ie:
- sexual contact
- transfusion
- contaminated needles
- perinatal transmission
What happens in the primary infection/seroconversion stage of HIV infection?
Virus gains entry locally (lymph tissue) then spreads to blood
What happens in the latent stage of HIV infection?
Virus replicates and evades immune system so levels rise
What happens in the symptomatic stage of HIV infection?
CD4 count < 350 and people start to feel unwell
What happens in the severe/AIDS stage of HIV infection?
CD4 count < 200 and patients have an increased risk of cancer
What are the main symptoms of acute HIV infection?
- fever
- weight loss
- headache
- lymphadenopathy
- skin rash
- nausea
- vomiting
- hepatomegaly
- splenomegaly
- myalgia
- oral thrush
Which factors affect HIV transmission?
- type of exposure (type of sexual act)
- viral level in blood
- condom use
- breaks in skin or mucosa
Which tests are used to diagnose HIV?
- blood tests (serology)
- blood tests (PCR)
- “rapid” test
What does serology of HIV detect?
HIV antigen (Ag) and HIV antibody (Ab)
What does a PCR of HIV detect?
HIV nucleic acid - detects very early infection (few days)
What does a “rapid” HIV test detect?
HIV antibody
Patients with which conditions are more at risk of contracting HIV?
- bacterial pneumonia/TB
- meningitis/dementia
- severe psoriasis
- chronic diarrhoea
- lymphoma/anal cancer
- cervical intrapithelial neoplasia (CIN)
- any STI/Hep B/Hep C
What are the aims of HIV treatment?
- reconstitute CD4 count
- reduce general inflammation
- reduce risk of transmission
- good quality of life
- normalise lifespan
Which strategies are used to treat and reduce the prevalence of HIV?
- anti-retroviral drugs (ARVs)
- increase condom usage
- prevention of mother-to-child transmission
- medical circumcision
- post and pre-exposure prophylaxis
Why is a HIV vaccine not possible?
Vaccine would target the envelope proteins but the virus constantly changes these proteins so a vaccine would not be possible
Which ARVs are used to treat HIV?
1) two nucleoside reverse transcriptase inhibitors (NRTIs) AND 2) non-nucleoside reverse transcriptase inhibitor (NNRTI) OR 3) protease inhibitor OR 4) integrate inhibitor OR 5) CCR5 entry inhibitor
Why are three ARVs given?
There are millions of rounds of viral replication each day and the virus mutates every 2-3 rounds so resistance to the drugs can develop in days. Three drugs makes it harder for a resistance to develop
