UNIT 2 (topic 4) HIV and ELISA test

Question 1

what does HIV stand for

Answer 1

Human Immunodeficiency Virus

Question 2

what does HIV do to the immune system

Answer 2

leads to the destruction of T cells

Question 3

define HIV dormancy

Answer 3

stops replicating after early stages and a trigger will restart replication

Question 4

how does HIV replicate

Answer 4

• HIV enters the bloodstream
• binds to the CD4 antigens on the membrane of helper T cells
• the capsid fuses with the T cell membrane, RNA and enzymes enter the T cell
• reverse transcriptase converts the RNA to DNA
• DNA moved to the T cell nucleus and inserted into the T cell’s DNA
• new DNA creates mRNA to make new viral proteins
• mRNA passes out the nucleus and uses the T cell ribosome to create HIV proteins
• HIV proteins break away from the T cell with a piece of membrane to form the lipid envolope

Question 5

what does AIDS stand for

Answer 5

acquired immunodeficiancy syndrome

Question 6

when does HIV become AIDS

Answer 6

when the T cell count is very low nd the body cannot fight the infection

Question 7

how can AIDS be diagnosed

Answer 7

• when CD4 count is low in blood
• development of opportunistic infections

Question 8

what are opportunistic infections

Answer 8

infections that can nomrally be neutrslised e.g. shingles, tuberculosis

Question 9

what does ELISA stand for

Answer 9

Enzyme-linked Immunosorbant Assay

Question 10

explain how the ELISA test works

Answer 10

• HIV antigens are attached to the bottom of plate
• add the blood sample, anti-HIV antibodies will bind to antigens if present
• the plate is washed out to remove unbound antibodies
• add anti-antibody antibody with an attached enzyme , if HIV anti-antibodies are present these will bind
• wash out to remove unbound antibodies
• add a colourless solution (complementory to the enzyme)
• if the enzyme is present, the solution will change colour