Approximately 3000-4500 subjects in total will be enrolled in the study into four different study populations. In Population 1, which is "at risk" group of about 2000-3000 subjects, roughly 2/3 will be individuals who are at risk of infection with HIV or hepatitis B or C, or who have signs or symptoms of hepatitis. Approximately 500 of these individuals are expected to be known HIV-positive individuals.