title: Analysis of neutralization specificities in polyclonal sera derived from human immunodeficiency virus type 1-infected individuals.
abstract: During human immunodeficiency virus type 1 (HIV-1) infection, patients develop various levels of neutralizing antibody (NAb) responses. In some cases, patient sera can potently neutralize diverse strains of HIV-1, but the antibody specificities that mediate this broad neutralization are not known, and their elucidation remains a formidable challenge. Due to variable and nonneutralizing determinants on the exterior envelope glycoprotein (Env), nonnative Env protein released from cells, and the glycan shielding that assembles in the context of the quaternary structure of the functional spike, HIV-1 Env elicits a myriad of binding antibodies. However, few of these antibodies can neutralize circulating viruses. We present a systematic analysis of the NAb specificities of a panel of HIV-1-positive sera, using methodologies that identify both conformational and continuous neutralization determinants on the HIV-1 Env protein. Characterization of sera included selective adsorption with native gp120 and specific point mutant variants, chimeric virus analysis, and peptide inhibition of viral neutralization. The gp120 protein was the major neutralizing determinant for most sera, although not all neutralization activity against all viruses could be identified. In some broadly neutralizing sera, the gp120-directed neutralization mapped to the CD4 binding region of gp120. In addition, we found evidence that regions of the gp120 coreceptor binding site may also be a target of neutralizing activity. Sera displaying limited neutralization breadth were mapped to the immunogenic V3 region of gp120. In a subset of sera, we also identified NAbs directed against the conserved, membrane-proximal external region of gp41. These data allow a more detailed understanding of the humoral responses to the HIV-1 Env protein and provide insights regarding the most relevant targets for HIV-1 vaccine design.
authors.affiliation: Vaccine Research Center, NIAID, NIH, Bethesda, Maryland 20892-3005, USA.
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Li
authors.forename: Krisha
authors.initials: K
authors.lastname: Svehla
authors.forename: Mark K
authors.initials: MK
authors.lastname: Louder
authors.forename: Diane
authors.initials: D
authors.lastname: Wycuff
authors.forename: Sanjay
authors.initials: S
authors.lastname: Phogat
authors.forename: Min
authors.initials: M
authors.lastname: Tang
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Migueles
authors.forename: Xueling
authors.initials: X
authors.lastname: Wu
authors.forename: Adhuna
authors.initials: A
authors.lastname: Phogat
authors.forename: George M
authors.initials: GM
authors.lastname: Shaw
authors.forename: Mark
authors.initials: M
authors.lastname: Connors
authors.forename: James
authors.initials: J
authors.lastname: Hoxie
authors.forename: John R
authors.initials: JR
authors.lastname: Mascola
authors.forename: Richard
authors.initials: R
authors.lastname: Wyatt
mesh_terms: D018604:Epitope Mapping; D015483:HIV Antibodies / Q000097:blood*; D015699:HIV Envelope Protein gp120 / Q000276:immunology; D015700:HIV Envelope Protein gp41 / Q000276:immunology; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D009500:Neutralization Tests
chemical_list: D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; C514793:gp120 protein, Human immunodeficiency virus 1; C514787:gp41 protein, Human immunodeficiency virus 1