Unique C2V3 sequence in HIV-1 envelope obtained from broadly neutralizing plasma of a slow progressing patient conferred enhanced virus neutralization

PLoS One. 2012;7(10):e46713. doi: 10.1371/journal.pone.0046713. Epub 2012 Oct 3.

Abstract

Broadly neutralizing antibodies to HIV-1 usually develops in chronic infections. Here, we examined the basis of enhanced sensitivity of an env clone amplified from cross neutralizing plasma of an antiretroviral naïve chronically infected Indian patient (ID50 >600-fold higher compared to other autologous env clones). The enhanced autologous neutralization of pseudotyped viruses expressing the sensitive envelope (Env) was associated with increased sensitivity to reagents and monoclonal antibodies targeting distinct sites in Env. Chimeric viruses constructed by swapping fragments of sensitive Env into resistant Env backbone revealed that the presence of unique residues within C2V3 region of gp120 governed increased neutralization. The enhanced virus neutralization was also associated with low CD4 dependence as well as increased binding of Env trimers to IgG1b12 and CD4-IgG2 and was independent of gp120 shedding. Our data highlighted vulnerabilities in the Env obtained from cross neutralizing plasma associated with the exposure of discontinuous neutralizing epitopes and enhanced autologous neutralization. Such information may aid in Env-based vaccine immunogen design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Gene Products, env / genetics
  • Gene Products, env / metabolism*
  • HIV-1 / genetics
  • HIV-1 / metabolism*
  • Humans
  • Mutagenesis, Site-Directed

Substances

  • Gene Products, env

Grants and funding

This study was supported by a research grant from the Department of Biotechnology, Ministry of Science and Technology, Government of India to JB (BT/PR12853/MED/29/141/2009). RR and DS are recipients of Senior Research Fellowships from the Council of Scientific and Industrial Research (CSIR), and the University Grants Commission (UGC), Government of India respectively. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.