Isolation of Cross-Clade HIV-Neutralizing Human Antibodies from Memory B Cell Repertoires Using Short Term Culture and High-Throughput Primary Neutralization Screens (38.17)

Abstract

Abstract Background. We have recently isolated 2 broadly neutralizing monoclonal antibodies (bNAbs), PG9 and PG16, from an HIV-infected subject in an African Protocol G cohort that are more potent than the bNAbs discovered in the past decade. The discovery highlights our human antibody (Ab) discovery approach based on short-term memory B cell culture, high-throughput primary microneutralization screening, and recombinant monoclonal antibody (mAb) reconstitution (Walker LM, et al, 2009, Science, 326:285-9). The epitope specificities of PG9 and PG16 reveal a novel target for designing vaccine immunogens that may elicit broad anti-HIV protection. To identify additional epitopes for vaccine design, we extended the bNAb discovery to more HIV-infected subjects. Method. We selected several HIV-infected subjects with broad neutralization activity in serum. Memory B cells from these elite neutralizers were activated and the IgG-containing culture media were screened for neutralizing activity against multiple pseudotyped viruses. mAbs were rescued from selected B cell culture wells by RT-PCR and subcloning. Results. From an HIV-infected elite neutralizer, we have identified in the primary screen multiple human Abs that cross-neutralize MGRM-C-26 of clade C, and 93BR020 and JR-CSF of clade B. Antibodies that neutralize either MGRM-C-26 alone or 94UG103 of clade A alone were also detected. Recombinant mAbs are currently being rescued for further characterization. (Supported by IAVI and USAID)