title: Glycans flanking the hypervariable connecting peptide between the A and B strands of the V1/V2 domain of HIV-1 gp120 confer resistance to antibodies that neutralize CRF01_AE viruses.
abstract: Understanding the molecular determinants of sensitivity and resistance to neutralizing antibodies 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 individuals infected with CRF01_AE viruses. The libraries were screened with plasma containing broadly neutralizing antibodies, and neutralization sensitive and resistant variants were selected for sequence analysis. In vitro mutagenesis 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 structure. Although N136 has previously been implicated in the binding of broadly neutralizing monoclonal antibodies, this glycosylation site appears to inhibit the binding of neutralizing antibodies in plasma from HIV-1 infected subjects. Previous studies have reported that the length of the V1/V2 domain in transmitted founder viruses is shorter and possesses fewer glycosylation sites compared to viruses isolated from chronic infections. Our results suggest that vaccine immunogens based on recombinant envelope proteins from clade CRF01_AE viruses might be improved by inclusion of envelope proteins that lack these glycosylation sites. This strategy might improve the efficacy of the vaccines used in the partially successful RV144 HIV vaccine trial, where the two CRF01_AE immunogens (derived from the A244 and TH023 isolates) both possessed glycosylation sites at N136 and N149.
authors: Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America.
authors: Sara M
authors: SM
authors: O'Rourke
authors: National HIV Repository and Bioinformatics Center (Thailand), Department of Microbiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Ruengpung
authors: R
authors: Sutthent
authors: Monogram Biosciences, South San Francisco, California, United States of America.
authors: Pham
authors: P
authors: Phung
authors: Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America.
authors: Kathryn A
authors: KA
authors: Mesa
authors: Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America.
authors: Normand L
authors: NL
authors: Frigon
authors: Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America.
authors: Briana
authors: B
authors: To
authors: National HIV Repository and Bioinformatics Center (Thailand), Department of Microbiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Navin
authors: N
authors: Horthongkham
authors: Monogram Biosciences, South San Francisco, California, United States of America.
authors: Kay
authors: K
authors: Limoli
authors: Monogram Biosciences, South San Francisco, California, United States of America.
authors: Terri
authors: T
authors: Wrin
authors: Department of Biomolecular Engineering, Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America; Gladstone Institute of Virology & Immunology, San Francisco, California, United States of America.
authors: Phillip W
authors: PW
authors: Berman
mesh_terms: D000595:Amino Acid Sequence; D057134:Antibodies, Neutralizing / Q000276:immunology*; D055030:Drug Users; D005838:Genotype; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology*; D023581:HIV Fusion Inhibitors / Q000494:pharmacology; D015658:HIV Infections / Q000276:immunology / Q000821:virology; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009500:Neutralization Tests; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D011134:Polysaccharides / Q000276:immunology*; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs / Q000276:immunology*; D016415:Sequence Alignment
chemical_list: D057134:Antibodies, Neutralizing; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D023581:HIV Fusion Inhibitors; D010455:Peptides; D011134:Polysaccharides