Design of an Escherichia coli expressed HIV-1 gp120 fragment Immunogen that binds to b12 and induces broad and potent neutralizing antibodies

Bhattacharyya, Sanchari and Singh, Pranveer and Rathore, Ujjwal and Purwar, Mansi and Wagner, Denise and Arendt, Heather and DeStefano, Joanne and LaBranche, Celia C and Montefiori, David C and Phogat, Sanjay and Varadarajan, Raghavan (2013) Design of an Escherichia coli expressed HIV-1 gp120 fragment Immunogen that binds to b12 and induces broad and potent neutralizing antibodies. In: Journal of Biological Chemistry, 288 (14). pp. 9815-9825.

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Abstract

b12, one of the few broadly neutralizing antibodies against HIV-1, binds to the CD4 binding site (CD4bs) on the gp120 subunit of HIV-1 Env. Two small fragments of HIV-1 gp120, b121a and b122a, which display about 70% of the b12 epitope and include solubility-enhancing mutations, were designed. Bacterially expressed b121a/b122a were partially folded and could bind b12 but not the CD4bs-directed non-neutralizing antibody b6. Sera from rabbits primed with b121a or b122a protein fragments and boosted with full-length gp120 showed broad neutralizing activity in a TZM-bl assay against a 16-virus panel that included nine Tier 2 and 3 viruses as well as in a five-virus panel previously designed to screen for broad neutralization. Using a mean IC50 cut-off of 50, sera from control rabbits immunized with gp120 alone neutralized only one virus of the 14 non-Tier 1 viruses tested (7%), whereas sera from b121a- and b122a-immunized rabbits neutralized seven (50%) and twelve (86%) viruses, respectively. Serum depletion studies confirmed that neutralization was gp120-directed and that sera from animals immunized with gp120 contained lower amounts of CD4bs-directed antibodies than corresponding sera from animals immunized with b121a/b122a. Competition binding assays with b12 also showed that b121a/2a sera contained significantly higher amounts of antibodies directed toward the CD4 binding site than the gp120 sera. The data demonstrate that it is possible to elicit broadly neutralizing sera against HIV-1 in small animals.

Item Type:	Journal Article
Publication:	Journal of Biological Chemistry
Publisher:	American Society for Biochemistry and Molecular Biology
Additional Information:	Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
Keywords:	Antibodies; HIV-1; Humoral Response; Protein Design; Vaccine Development; Competition Binding; Immune Maturation; Prime-Boost
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	04 Jun 2013 09:41
Last Modified:	04 Jun 2013 09:41
URI:	http://eprints.iisc.ac.in/id/eprint/46516

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