Neutralizing antibodies in HIV (HTLV-III) infection: correlation with clinical outcome and antibody response against different viral proteins

Sequential serum samples, collected over a 2-3 year follow-up period, of 28 HIV-infected individuals were tested for the presence of neutralizing antibodies against one HIV isolate, HTLV-III(B), and titrated, by Western blotting, against different HTLV-III specific proteins. Neutralizing antibodies were found in 66% of the samples tested and highest neutralization titres observed in cases with lymphadenopathy syndrome. Antibody titres against the viral proteins also seemed to be highest in cases with LAS. Neutralization titres correlated well with antibodies to envelope glycoproteins gp41 and gp120 and to one of the core proteins, p17. An increase in neutralization titre during the follow-up period was associated with a stable clinical course. Furthermore, the occurrence of antibodies directed against the external envelope glycoprotein (gp120) in the initial serum sample correlated well with a stable clinical course. The results suggest that neutralizing activity in the serum, particularly that evoked against gp120, may have some prognostic significance, and that several distinct antigenic epitopes on the virus may be a target for neutralizing antibodies.