Serological study of subjects with seroconversion to human immunodeficiency virus.

Twelve homosexual males who seroconverted to human immunodeficiency virus (HIV) were followed-up for over two years. Analysis of sera by immunoblotting showed that seroconversion was characterized by the presence of specific IgM that reacted mainly with viral polypeptides of molecular weights ranging from 17 Kd to 55 Kd. Specific IgG to all HIV proteins was detected. Immunoblotting showed that antibodies to 24 Kd core protein alone or in association with 17 Kd polypeptide appeared first in some cases. Virus antigen was detected in six patients: five subjects were positive at the time of seroconversion, and one became positive afterwards. It is concluded that detection of IgG and IgM antibody against the different viral polypeptides, together with detection of viral antigen is necessary in order to determine the stage of HIV infection.