Serological markers in early stages of human immunodeficiency virus infection in haemophiliacs.

Immunoassays for human immunodeficiency virus antigen (HIV Ag) and for antibody to HIV core and envelope (CIA-RA) were done on serial specimens from 40 haemophiliacs who had become seropositive on screening by enzyme-linked immunosorbent assay (ELISA). HIV Ag was detectable in 9 subjects and antibodies to envelope in 11 subjects before ELISA seroconversion. The apparent sequence of markers is HIV Ag, antibody to envelope, then antibody to core. Antigenaemia could be detected as soon as 2 weeks after infection and lasted 3-5 months. 82% agreement was seen between CIA-RA and western blot; CIA was more sensitive to envelope antibody and western blot was more sensitive to core antibody.