HIV

Question 1

What are AIDS?

Answer 1

AIDS (acquired immune deficiency syndrome) caused by infection with HIV
A syndrome is a collection of sympotoms related to the same cause
Symptoms of AIDS - opportunistic infections - susceptible due to weakened immune system

Question 2

Whats HIV?

Answer 2

Complex virus - RNA surrounded by 2 sided protein capsid enclosed in a layer of viral protein
Lipid envelope formed from host cell membrane
2 copies of mRNA

Question 3

Describe transmission of HIV

Answer 3

Not tough virus and can’t survive outside the body for long
Bodily fluids have to be transferred directly into the next body by:
sharing needles, unprotected sex, blood to blood transfer through cuts, transmission through breast milk

Question 4

New virus particles destroy T cells

Answer 4

New HIV virus proteins produced with glycoproteins and nuclear material are assembled into new viruses
New virus bud out of T cell taking some cell membrane with them as their envelope and killing the cell as they leave
Infected T helper cells will be destroyed by T killer cells
As number of viruses increases, number of T helper cells decrease so macrophages B cells and T killer cells aren’t activated so immune system deficient

Question 5

Describe Acute Phase of HIV

Answer 5

HIV antibodies appear in blood
Symptoms - fever, sweats, headache.
Rapid replication of virus and loss of T helper cells
After a few weeks infected T helper cells are recognised by T killer cells destroying them
Reduces rate of replication

Question 6

Describe Chronic Phase of HIV

Answer 6

Virus continues to reproduce rapidly but numbers are kept in check by immune system there may be no symtoms and dormant diseases ie TB may reactivate

Question 7

Describe Disease Phase of HIV

Answer 7

Increases viral load and decline in T helper cells indicate onset of AIDS
Immune system is now compromised due to lack of T helper cells and patient is more prone to opportunistic infections ef TB

Question 8

Diagnosis of HIV

Answer 8

HIV test
Gay men and black African men are more prone to get it
Early treatment
Blood test
Look for antibodies

Question 9

Treatment of HIV

Answer 9

Cannot be treated as virus hides in T helper cells
Antiretroviral drugs - reduce viral production
Protease inhibitors - inhibit proteases catalyses cutting of proteins
Reverse transcriptase inhibitors

Question 10

Describe HIV replication

Answer 10

HIV invades T helper cells
Glycoprotein molecule, gp120, on viral surface bind to CD4 receptors on T helper cell surface
Envelope surrounding the virus fuses with T helper cell membrane enabling viral RNA to enter the cell