5.7 human immunodeficiency virus

Question 1

how does HIV replicate itself? (7)

Answer 1

1) HIV enters bloodstream & circulate around the body
2) attachment protein binds to CD4 receptor on helper T cells
3) protein capsid fuses with cell-surface membrane -> RNA & enzymes of HIV enters helper T cell
4) reverse transcriptase converts viral RNA into DNA & intergrase it into host DNA
5) mRNA is created in host cells which codes for viral proteins
6) mRNA passes out through nuclear pores & makes HIV particles
7) HIV particles break away from helper T cells

Question 2

how could HIV causes symptoms of AIDS?

Answer 2

targeting helper T cells affect normal cell functioning
-> no B cells stimulated to produce antibodies / cytotoxic T cells to kill pathogen-infected cells

-> no memory cells produced / producing infected memory cells which leads to being susceptible to other infections & cancers

Question 3

how is the ELISA test carried out? (8)

Answer 3

1) attach sample to surface where antigens will be attached
2) wash the surface to remove unattahed antigens
3) add antibodies that are specific to antigen
4) wash to remove excess antibody
5) add 2nd antibody (with attached enzyme) which binds to 1st antibody
6) add colourless substrate
7) enzyme acts & forms colour product
8) amount of antigen present = intensity of colour

Question 4

! structure of HIV virus