Screening test for HIV infection in a patient prior to the development of antibodies (in window period): March 2013

Ans. C i.e. p24 antigen. HIV infection is identified either by the detection of HIV-specific antibodies in serum or plasma or by demonstrating the presence of the virus by nucleic acid detection using polymerase chain reaction (PCR), p24 antigen testing or, rarely these days, by growing virus in cell culture. Antibody testing is the method most commonly used to diagnose HIV infection. With the highly sensitive HIV-1/HIV-2 enzyme immunoassay (EIA) tests currently on the market, seroconversion can be detected within two to three weeks of infection in the majority of cases. In a small number of early seroconveers who are still in the 'window period', the p24 antigen may become positive before antibody is detectable.