Simultaneous induction of multiple classes of broadly neutralizing antibody precursors by combination germline-targeting immunization in nonhuman primates.

Inducing broadly neutralizing antibodies (bnAbs) against HIV remains a key challenge in vaccine development. Germline-targeting immunogens have effectively primed bnAb B cell lineages to individual HIV envelope epitopes in humans and nonhuman primates. However, eliciting consistent bnAb breadth requires the induction of multiple bnAb classes. We investigated whether immunization with a combination of germline-targeting immunogens could concurrently prime multiple bnAb lineages in nonhuman primates. Animals were immunized with three immunogens, targeting distinct epitopes: the V3-glycan/N332 supersite, the V2 Apex region, and the membrane-proximal external region (MPER), either individually or in combinations of two or all three. Triple combination immunization transiently reduced V2 Apex and V3-glycan responses, but by 8 weeks postboost, bnAb precursor lineages were observed to all three epitopes. Similar somatic hypermutation was observed across groups, indicative of permissive germinal center responses. These findings support combination germline-targeting immunization as a viable strategy to prime multiple bnAb lineages simultaneously.