HIV

Question 1

what is the relevance of HIV globally and in the UK?

Answer 1

• still millions of people infected (largest HIV burden is in africa)
• substantially fewer deaths in UK due to HIV
• can develop to AIDs

Question 2

what is the structure of HIV?

Answer 2

HIV is single stranded RNA retrovirus

Question 3

what is the lifecycle of HIV?

Answer 3

1. free virus
2. binding and fusion: gp120 portion of envelope binds to CD4 receptor found on T cell surface allowing virus to fuse with cell
3. infection: virus penetrates cell and empties contents into cell
4. reverse transcription: single stranded RNA concverted to double stranded DNA. by reverse transcriptase
5. integration: viral DNA is combined with the cells own DNA by integrase
6. transcription: infected cell divides and viral DNA is read making long protein chains
7. assembly: sets of viral protein chains come together
8. budding: immature virus pushes out of cell taking some cell membrane with it
9. immature virus breaks free of infected cell
10. maturation: protein chains are cut by protease and make a new working virus

Question 4

what does a CD4 count below 200 indicate?

Answer 4

HIV progression to AIDS

Question 5

what factors affect HIV transmission?

Answer 5

• type of exposure: type of sexual contact, transfusion vs needlestick
• breaks in skin or mucosa: other STI, sexual assault
• viral level in blood

Question 6

how is HIV treated?

Answer 6

ASAP with anti-retroviral drugs: 3 ARVs used
* target the receptors involved in allowing enterance of virus into cell
* targets integrase
* targets protease

Question 7

why are 3 ARVs given to treat HIV?

Answer 7

• millions of rounds of viral replication each day
• virus mutates every 2-3 rounds which means resistance to drug increases each day
  3 drugs reduces chance of developing resistance

Question 8

what are ways of preventing HIV?

Answer 8

• promote condom usage
• male circumcision
• wide spread testing
• post expose prophylaxis
• pre exposure prophylaxis