I: HIV

Question 1

Describe the relevance of HIV in a global context.

Answer 1

There are 37 million causes of HIV world wide with 2 million new cases being diagnosed on average each year.

Question 2

Describe the relevance of HIV in context of the UK.

Answer 2

There are currently approximately 100,000 cases of HIV in the UK with only approximately 6,000 new diagnosises each year.

However some areas such as the midlands have a higher incidence rate than average.

Question 3

Describe the structure of HIV.

Answer 3

• Retrovirus (has RNA that needs to be converted into DNA)
• Surface glycoproteins that are attracted to CD4 receptors on other cells (such as T lymphocytes, macrophages and monocytes)
• Enzymes (reverse transcriptase, protease, intergrase)
• Enveloped

Question 4

Describe how HIV replicates.

Answer 4

The free virus binds and fuses with the CD4 and co receptor on the host membrane.

The emptied contents is reverse transcribed by the action of reverse transcriptase and then integrated into the hosts DNA via the action of intergrase.

This viral DNA is transcribed and translated and them assembled before budding off, taking some of the cell membrane with it.

Protease in a mature virus cuts the protein into individual proteins that combine to form the working virus.

Question 5

Describe how patients can be tested for HIV.

Answer 5

Rapid: Usually detects HIV antibody. Must be confirmed with serology.

Serology: This result can be achieved in the same day and tests for Ag (antigen which is viral protein) and Ab (immunoglobulin in response to antigen)

PCR: highly sensitive and so detects early infection, however results can take up to a week to be achieved. Tests for HIV RNA

Question 6

How is HIV treated?

Answer 6

Everyone is treated with three antiretroviral viral drugs at the immediate point of diagnosis.

Question 7

How is HIV transmitted?

Answer 7

Contact of infected bodily fluids e.g. Blood, broken skin

Question 8

How can HIV be prevented?

Answer 8

• Increase condom usage
• Prevention of mother to child transmission
• ARV treatment as prevention
• Medical circumcision
• Post-exposure prophylaxis
• Pre-exposure prophylaxis

Question 9

Why are patients treated with 3 antiretroviral drugs.

Answer 9

Harder to develop resistance.

Question 10

What are the targets for HIV treatment?

Answer 10

• Receptors on host and virus

- Enzymes

Question 11

Give some examples of ARV drugs.

Answer 11

• Nucleoside reverse transcriptase inhibitors
• Non-Nucleoside reverse transcriptase inhibitors
• Protease inhibitors
• Intergrase inhibitors