2G12/PGT-binding yeast glycoprotein Gp38 elicits mannose-specific HIV-1 Env cross-reactive antibodies

Abstract

Results Using the newly identified, glycan-specific PGT bNAbs to search for their binders from a triple mutant(TM) strain of Saccharomyces cerevisiae, we found that the PGT bNAbs not only bind to the previously identified 2G12reactive glycoproteins but also recognize several unknown proteins in TM yeast. One of them was identified as a short version of Gp38 with N-terminus truncation. Based on immunization of rabbits with various formulations and strategies, we found that a high titer of HIV-1 Env cross-reactive antibodies was induced when using a promiscuous T-cell epitope peptide conjugated Gp38 in a formulation with a Toll-like receptor 2 agonist and aluminum salts. The Gp38-elicited antibodies could bind to a broad range of monomeric gp120s from HIV and SIV. Moreover, the antibodies could also efficiently neutralize HIV-1 pseudoviruses when the viruses were produced in the presence of a mannosidase inhibitor kifunensine, which enriches high-mannose Man9GlcNAc2 N-linked glycans. Glycan microarray analysis showed that these antibodies bind to the synthetic Mana1,2-Mana1,2-Man containing oligosaccharides.