The identification badge of HIV. When watchmen cells see it, they know they are dealing with a dangerous intruder. The presence of p24 in the blood allows diagnosis of an HIV infection during the few weeks following exposure. Put two fingers inside the condom and push the inner ring as far into the vagina as it will go. The whole vaginal cavity should be snugly lined.

one of the main structural proteins of HIV.

A protein in HIV's inner core. The p24 antigen blood test is often used to detect HIV infection.