Early appearance of simian immunodeficiency virus (SIV) antigen and antibodies as variables in evaluating antiviral drugs in macaques.

SIV infection in macaques has become an important animal model for HIV-1 infection in humans. An antibody assay was therefore developed and compared to a commercially available antigen assay with respect to their usefulness to monitor the course of simian immunodeficiency virus (SIV) infection in cynomolgus monkeys. A peptide, JB6T, consisting of 21 amino acids with the sequence NSWGCAFRQVCHTTVPWVNDS corresponding to a segment in the env protein of human immunodeficiency virus (HIV) type 2 was used as antigen in an enzyme-linked immunosorbent assay (ELISA). JB6T was found to detect IgG and IgM antibodies to viral antigens with high specificity. The earliest anti-SIV IgM antibodies were detected at days 13-16, with a maximum at day 20 and subsequently the levels fell. Specific IgG antibody levels increased at day 16-20 after SIV infection and reached a plateau at day 60. The commercially available HIV-1 p24/26 antigen test could, due to cross-reactivity, be employed to detect SIV antigen delay, peak and duration.