Bacterially expressed HIV-1 gp120 outer-domain fragment immunogens with improved stability and affinity for CD4-binding site neutralizing antibodies

Rathore, Ujjwal and Purwar, Mansi and Vignesh, Venkada Subramanian and Das, Raksha and Kumar, Aditya Arun and Bhattacharyya, Sanchari and Arendt, Heather and DeStefano, Joanne and Wilson, Aaron and Parks, Christopher and La Branche, Celia C and Montefiori, David C and Varadarajan, Raghavan (2018) Bacterially expressed HIV-1 gp120 outer-domain fragment immunogens with improved stability and affinity for CD4-binding site neutralizing antibodies. In: JOURNAL OF BIOLOGICAL CHEMISTRY, 293 (39). pp. 15002-15020.

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Abstract

Protein minimization is an attractive approach for designing vaccines against rapidly evolving pathogens such as human immunodeficiency virus, type 1 (HIV-1), because it can help in focusing the immune response toward 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 (ODEC) that bound CD4-binding site (CD4bs) ligands with 3-12 m affinity and elicited a modest neutralizing antibody response in rabbits. In this study, we have optimized ODEC using consensus sequence design, cyclic permutation, and structure-guided mutations to generate a number of variants with improved yields, biophysical properties, stabilities, and affinities (K-D 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 ODEC, 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 among the tested immunogens. This study also provides insights into some of the biophysical correlates of improved immunogenicity.

Item Type:	Journal Article
Publication:	JOURNAL OF BIOLOGICAL CHEMISTRY
Publisher:	AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Additional Information:	Copy right for this article belong to AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Keywords:	protein design; mutagenesis; glycosylation; hydrogen-deuterium exchange; vaccine development; protein refolding; yeast surface display
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	16 Oct 2018 14:23
Last Modified:	16 Oct 2018 14:23
URI:	http://eprints.iisc.ac.in/id/eprint/60891

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