Question

Write any two biochemical/molecular diagnostic procedures for early detection of viral infection. Explain the principle of any one of them. [3 Marks]

Answer 1

Two molecular diagnostic methods are:

• ELISA
• Polymerase chain reaction [1 Mark]

Enzyme linked immuno-sorbent assay (ELISA) is based on the principle of antigen-antibody interaction. The antigen present in a samples is treated with a primary antibody specific for the antigen This leads to the formation of antigen-antibody complexes. This complex is treated with a secondary antibody which specifically binds to the primary antibody. This binding leads to formation of a coloured product, which can be measured. the amount of coloured product is directly proportional to the amount of antigen in the sample. [2 Marks]