DETERMINANTS OF ANTIBODY-RESPONSE AFTER RECOMBINANT GP160 BOOSTING INVACCINIA-NAIVE VOLUNTEERS PRIMED WITH GP160-RECOMBINANT VACCINIA VIRUS

Priming with a live recombinant vector followed by subunit boosting is a promising strategy for human immunodeficiency virus (HIV) immunizat ion. Twenty-nine vaccinia-naive volunteers were primed with gp160-reco mbinant vaccinia virus (HIVAC-1e) and boosted with recombinant (r) gp1 60 to define factors associated with the magnitude and specificity of antibody response after booster immunization. A longer interval betwee n inoculation and boost, two inoculations of HIVAC-1e with lesion form ation occurring after the first, and Western blot-detectable antibody to gp160 after inoculation were significantly associated with higher n eutralizing antibody titers and fusion-inhibiting activity after boost ing. HIVAC-1e-primed vaccinees were more likely to have antibody to V3 - and CD4-binding regions of gp120 and less likely to have antibody to constant regions 2 and 3 than vaccinees immunized with rgp160 alone. Priming volunteers with HIVAC-1e was a key determinant of the epitope specificity and magnitude of functional antibody responses induced by rgp160 boosting.