Q.If a person thinks he is infected with HIV, due to unprotected sex, and goes for a blood test. Do you think a test such as ELISA will help? If so why? If not, why?

Step 1. Recall ELISA's clinical role: the chapter explicitly states ELISA is a very important diagnostic tool to determine if a person is HIV positive or negative, by detecting the antibodies the immune system produces against HIV (or, alternatively, HIV antigens) in a blood/serum sample. Step 2. Confirm that ELISA is therefore the appropriate test for this person's situation: since they had unprotected sex and are worried about HIV specifically, an ELISA test on their blood is exactly the tool designed to answer that question, by checking for anti-HIV antibodies. Step 3. Add the necessary caveat: antibody-based tests like ELISA depend on the body having had enough time to actually produce detectable antibodies after infection (the 'window period'); if the test is taken very soon after a possible exposure, the antibody level may still be too low to detect, giving a false-negative result even if the person is in fact infected. Step 4. Give the practical recommendation: the person should s …

Confirm ELISA's designed use for HIV antibody detection, then qualify the answer with the antibody window-period limit …

• Answering a flat 'yes' without mentioning the window-period limitation that can cause a false negative soon after exposure. …