Determinants Of Antibody Response After Recombinant Gp160 Boosting In Vaccinia-Naive Volunteers Primed With Gp160-Recombinant Vaccinia Virus

Abstract
Priming with a live recombinant vector followed by subunit boosting is a promising strategy for human immunodeficiency virus (HIV) immunization. Twenty-nine vaccinia-naive volunteers were primed with gpl60-recombinant vaccinia virus (HIVAC-le) and boosted with recombinant (r) gp 160 to define factors associated with the magnitude and specificity of antibody response after booster immunization. A longer interval between inoculation and boost, two inoculations of HIVAC-le with lesion formation occurring after the first, and Western blot-detectable antibody to gp160 after inoculation were significantly associated with higher neutralizing antibody titers and fusion-inhibiting activity after boosting. HIVAC-le-primed vaccinees were more likely to have antibody to V3- and CD4-binding regions of gp 120 and less likely to have antibody to constant regions 2 and 3 than vaccinees immunized with rgp160 alone. Priming volunteers with HIVAC-le was a key determinant of the epitope specificity and magnitude of functional antibody responses induced by rgp 160 boosting.