gp120 Confer Resistance to Antibodies That Neutralize CRF01_AE Viruses

Understanding the molecular determinants of sensitivity and resistance to neutralizing anti-bodies is critical for the development of vaccines designed to prevent HIV infection. In this study, we used a genetic approach to characterize naturally occurring polymorphisms in the HIV envelope protein that conferred neutralization sensitivity or resistance. Libraries of closely related envelope genes, derived from virus quasi-species, were constructed from in-dividuals infected with CRF01_AE viruses. The libraries were screened with plasma con-taining broadly neutralizing antibodies, and neutralization sensitive and resistant variants were selected for sequence analysis. In vitromutagenesis allowed us to identify single amino acid changes in three individuals that conferred resistance to neutralization by these antibodies. All three mutations created N-linked glycosylation sites (two at N136 and one at N149) proximal to the hypervariable connecting peptide between the C-terminus of the A strand and the N-terminus of the B strand in the four-stranded V1/V2 domain β-sheet struc-ture. Although N136 has previously been implicated in the binding of broadly neutralizing monoclonal antibodies, this glycosylation site appears to inhibit the binding of neutralizin