Blood Borne viruses: HIV Flashcards
how does HIV attach to cells
via the gp120 portion of the envelope gene product on the HIV surface which binds to the CD4 molecule( glycoprotein on surface of T cells)
why is HIV a retrovirus
takes its RNA uses host material to form DNA and then converts that back into RNA again when the new viruses are formed.
Life cycle of HIV
1) free virus
2) Binding and fusion- virus binds to a CD4 molecule and fuses with the cell.
3) infection- virus penetrates cell. contents emptied into cell.
4) reverse transcription-viral RNA converted to DNA by reverse transcriptase
5) viral DNA is combined with the cell’s own DNA by the integrate enzyme
6) transcription- when the infected cell divides, the viral DNA is ‘read’ and long chains of proteins are made.
7) assembly- sets of viral protein chains come together
8) budding- immature virus pushes out of the cell, taking some cell membrane with it.
9) immature virus breaks free of the infected cell
10) maturation - protein chains in the new viral particle are cut by the protease enzyme into individual proteins that combine to make a working virus.
*ARVs target 2,4,5 &10.
how is HIV transmitted
contact of infected bodily fluids with mucosal tissue/ blood/ broken skin
- sexual contact
- transfusion
- contaminated needles
- perinatal transmission
what are the stages of HIV infection
1) primary infection/seroconversion
2) latent infection
3) symptomatic infection
4) severe infection / AIDs
symptoms of acute HIV infection
systemic- fever, weight loss central - malaise, headache, neuropathy mouth - sores, thrush oesophagus - sores lymph nodes- lyphadoneopathy skin - rash liver and spleen enlargement gastric - nausea, vommiting
factors affecting HIV transmission
type of exposure- type of sexual act, transfusion vs needlestick vs mucous membrane
viral level in blood
condom use
break in skin / mucosa - other STI, sexual assault
diagnostic tests for HIV
serology tests - detects HIV antigen and antibody
PCR- detects HIV nucleic acid
‘rapid tests’- detect HIV antibody
what strategies would u use to reduce the prevalence of HIV
anti-retroviral drugs -testing more people - increasing condom usage - prevention of mother to child transmission voluntary male circumcision
aims of HIV treatment
undetectable viral load reconstitute CD4 count/ immune system reduce systemic inflammation good quality fo life normalise life span reduce risk of transmission
why give more than 1 ARV to HIV patients
virus mutates
resistance to frug develops in days
