Studies of Antibody-Dependent Enhancement of Human Immunodeficiency Virus (HIV) Type 1 Infection Mediated by Fc Receptors Using Sera from Recipients of a Recombinant gp160 Experimental HIV-1 Vaccine
Subneutralizing concentrations of sera from human immunodeficiency virus (HIV)-1-infected patients augment HIV infection mediated by Fe receptor uptake by human monocytes and the monocytic cell line U937. Antibody-dependent enhancement (ADE) and neutralization activity were studied in the sera of HIV-1 antibody-negative volunteers who had been immunized with three 40-μg doses of a recombinant gp 160 (rgp160) candidate HIV vaccine. Volunteers were vaccinated with rgp 160 or a hepatitis B vaccine as a control on days 0, 30, and 180. Sera were obtained before and after three doses of vaccine and were tested for ADE and neutralization activity. Serum samples collected before vaccination showed neither neutralization nor ADE activity. Thirteen sera from volunteers who received gp160 and four from placebo recipients failed to show ADE. Three sera showed low levelsof neutralization of strain IIIB of HIV. Vaccination with this dose of rgp160 produced neutralizing antibodies in some subjects but did not induce detectable enhancing antibodies.