title: Sequences in glycoprotein gp41, the CD4 binding site, and the V2 domain regulate sensitivity and resistance of HIV-1 to broadly neutralizing antibodies.
abstract: The swarm of quasispecies that evolves in each HIV-1-infected individual represents a source of closely related Env protein variants that can be used to explore various aspects of HIV-1 biology. In this study, we made use of these variants to identify mutations that confer sensitivity and resistance to the broadly neutralizing antibodies found in the sera of selected HIV-1-infected individuals. For these studies, libraries of Env proteins were cloned from infected subjects and screened for infectivity and neutralization sensitivity. The nucleotide sequences of the Env proteins were then compared for pairs of neutralization-sensitive and -resistant viruses. In vitro mutagenesis was used to identify the specific amino acids responsible for the neutralization phenotype. All of the mutations altering neutralization sensitivity/resistance appeared to induce conformational changes that simultaneously enhanced the exposure of two or more epitopes located in different regions of gp160. These mutations appeared to occur at unique positions required to maintain the quaternary structure of the gp160 trimer, as well as conformational masking of epitopes targeted by neutralizing antibodies. Our results show that sequences in gp41, the CD4 binding site, and the V2 domain all have the ability to act as global regulators of neutralization sensitivity. Our results also suggest that neutralization assays designed to support the development of vaccines and therapeutics targeting the HIV-1 Env protein should consider virus variation within individuals as well as virus variation between individuals.
authors.affiliation: Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, California, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: O'Rourke
authors.forename: Becky
authors.initials: B
authors.lastname: Schweighardt
authors.forename: Pham
authors.initials: P
authors.lastname: Phung
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Mesa
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Vollrath
authors.forename: Gwen P
authors.initials: GP
authors.lastname: Tatsuno
authors.forename: Briana
authors.initials: B
authors.lastname: To
authors.forename: Faruk
authors.initials: F
authors.lastname: Sinangil
authors.forename: Kay
authors.initials: K
authors.lastname: Limoli
authors.forename: Terri
authors.initials: T
authors.lastname: Wrin
authors.forename: Phillip W
authors.initials: PW
authors.lastname: Berman
mesh_terms: D057134:Antibodies, Neutralizing / Q000737:chemistry*; D001665:Binding Sites; D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D019295:Computational Biology / Q000379:methods; D004252:DNA Mutational Analysis; D015723:Gene Library; D057809:HEK293 Cells; D019302:HIV Envelope Protein gp160 / Q000737:chemistry; D015700:HIV Envelope Protein gp41 / Q000235:genetics* / Q000276:immunology; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D008957:Models, Genetic; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA
chemical_list: D057134:Antibodies, Neutralizing; D019302:HIV Envelope Protein gp160; D015700:HIV Envelope Protein gp41