CELLS & THE IMMUNE SYSTEM

INDIRECT ELISA

• HIV  antigen is bound to the bottom of a well in a well plate.
• A sample of the patients blood plasma, might contain several diff antibodies, is added to the well. If there are any HIV- specific antibodies in the plasma these will bind to the HIV antigen stuck to the bottom of the well. The well is then washed out to remove any unbound antibodies.
• A secondary antibody (has a specific enzyme attached to it) is added to the well.
• This secondary antibody can bind to the HIV specific antibody(primary antibody).
• The well is washed out again to remove any unbound secondary antibody. The well is washed out again to remove any unbound secondary antibody.
• A solution is added to the well. This contains a substrate which is able to react with the enzyme attached to the secondary antibody & produce a coloured product.
• If the solution changes colour it indicates that the patient has HIV- specific antibodies in their blood and is infected with HIV.

1. The attachement protein attaches to a receptor molecule on the cell membrane of the host HELPER T-CELL

2. The caspid is released into the cell, where it uncoats and releases the genetic material (RNA) into the cells cytoplasm.

3. Inside the cell, reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template.

4. From this, double stranded DNA is made and inserted into the human DNA.

5. Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA.

6. The viral proteins are assembled into new viruses, which bud from the cell and go on to infect other cells.