HIV (6.6)

Question 1

Describe the structure of HIV

Answer 1

HIV particles contain two copies of a single-stranded RNA genome within a conical capsid surrounded by a plasma membrane of host-cell origin containing viral envelope proteins.

Question 2

Explain how HIV infects the host cell

Answer 2

The HIV receptors bind to the CD4 receptors of the T helper cell. This leads to the fusion of the HIV cell into the host cell.

Question 3

Following the infection of its host cell new HIV molecules are produced. Describe the sequence of events leading to the production of new HIV particles

Answer 3

viral RNA moves into the nucleus and with the enzyme reverse transcriptase HIV RNA is transcribed and then translated by ribosomes to form new particles

Question 4

List the impacts an HIV infection has on the immune system

Answer 4

Immunodeficiency, decrease in healthy T helper cells, decreased amounts of B helper cells and T killer cells as less cytokines being released to call on them

Question 5

An HIV infection has three stages. List these three stages and explain why the final stage can result in the death of an individual being infected

Answer 5

Stage 1 = acute stage, where immune system can cope with HIV infection and fight it off. Preventing transcription of viral RNA and destroying infected T helpers
Stage 2 = chronic stage, as immune system can only temporarily fight HIV infection it will start to spread and worsen again. HIV particles start to overwhelm immune system and more T helpers infected
Stage 3 = development of AIDS. This is where immunodeficiency is likely to be present where the immune system is unable to fight against simple viral infections. Not being able to fight these infections will result in death