PMID: 30093409
Title: Bacterially expressed HIV 1 gp120 outer domain fragment immunogens with improved stability and affinity for CD4 binding site neutralizing antibodies
Abstract: Protein-minimization is an attractive approach for designing vaccines against rapidly evolving pathogens such as HIV-1 since it can help in focussing the immune response towards conserved conformational epitopes present on complex targets. The outer domain (OD) of HIV-1 gp120 contains epitopes for a large number of neutralizing antibodies and therefore is a primary target for structure-based vaccine design. We have previously designed a bacterially expressed outer domain immunogen (OD) that bound CD4 binding site (CD4bs) ligands with 3-12µM affinity and elicited a modest neutralizing antibody response in rabbits. In this study, we have optimized OD using consensus sequence design, cyclic permutation and structure-guided mutations to generate a number of variants with improved yields, biophysical properties, stabilities and affinities (KD of 10-50 nM) for various CD4bs targeting, broadly neutralizing antibodies, including the germline reverted version of the broadly neutralizing antibody, VRC01. In contrast to OD, the optimized immunogens elicited high anti-gp120 titers in rabbits as early as 6 weeks post-immunization, before any gp120 boost was given. Following two gp120 boosts, sera collected at week 22 showed cross-clade neutralization of Tier 1 HIV-1 viruses. Using a number of different prime: boost combinations, we have identified a cyclically permuted OD fragment as the best priming immunogen, and a trimeric, cyclically permuted gp120 as the most suitable boosting molecule amongst the tested immunogens. This study also provides insights into some of the biophysical correlates of improved immunogenicity.
Date: 1970-08-22
Year: 2018
Journal: J. Biol. Chem.
PMID Author: Rathore U, Purwar M, Vignesh VS, Das R, Kumar AA, Bhattacharyya S, Arendt HE, DeStefano J, Wilson A, Parks C, LaBranche CC, Montefiori DC, Varadarajan R
IAVI Topics: HIV Immunogen Design

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