Antibody response to a synthetic peptide covering a LAV-1/HTLV-IIIB neutralization epitope and disease progression.

Sequential sera of homosexual men participating in a prospective study on the incidence of HIV-1 infection and risk factors for AIDS were tested for the presence of antibodies to a synthetic 17-mer (Neu21; KSIRIQRGPGRAFVTIG) representing a neutralization epitope as present on the LAV-1/HTLV-IIIB strain of HIV-1. Of 191 at entry, 143 (75%) HIV-1-seropositive men remained anti-Neu21-negative during the follow-up period of 36 months. Thirty-seven (19%) HIV-1-seropositive men were persistently anti-Neu21-positive. Eleven (6%) HIV-1 seropositive men seroconverted for anti-Neu21 during follow-up. Of 75 men developing antibodies to HIV-1, 17 (23%) developed antibodies to Neu21. The incidence of anti-Neu21 seroconversion (calculated as attack rate) after 36 months was significantly lower (P less than 0.00001) among HIV-1-seropositive individuals (8%) than among the 75 HIV-1 seroconverters tested (25%), indicating that seroconversion to this neutralization domain occurs early during infection. AIDS and AIDS-related complex were diagnosed in 17% of the anti-Neu21 negatives and in 11% of the anti-Neu21 positives; this difference was not significant. The presence of HIV-1 antigen (29 versus 28%), the absence of antibodies to core proteins (45 versus 46%) and low CD4+ cell numbers (34 versus 40%) were not seen more frequently among anti-Neu21 negatives than among anti-Neu21 positives. These results argue against a role for antibodies to this LAV-1/HTLV-IIIB neutralization domain in protection against disease progression.