title: Cross-subtype neutralizing antibodies induced in baboons by a subtype E gp120 immunogen based on an R5 primary human immunodeficiency virus type 1 envelope.
abstract: Global human immunodeficiency virus type 1 (HIV-1) diversity may require engineering vaccines to express antigens representing strains prevalent in the target population of vaccine testing. The majority (90%) of incident infections in Thailand are genetic subtype E, with a small percentage of subtype B infections in the intravenous drug user populations. We have evaluated and compared the binding and HIV-1 neutralizing properties of serum antibodies induced in baboons by CHO cell-expressed monomeric gp120 derived from a CCR5-using (R5) subtype E primary HIV-1CM235 or a CXCR4-using (X4) subtype B T-cell line-adapted (TCLA) HIV-1SF2 isolate. In contrast to the subtype-specific HIV-1 neutralizing antibodies induced with recombinant HIV-1SF2 gp120 (rgp120SF2), rgp120CM235 immunization induced antibodies capable of neutralizing both subtype E and subtype B TCLA HIV-1 isolates. However, neither immunogen induced antibodies capable of neutralizing primary HIV-1 isolates. Antibody induced by rgp120CM235 preferentially bound natively folded gp120 and retained strong cross-reactivity against multiple gp120 strains within subtype E as well as subtype B. In contrast, antibody responses to rgp120SF2 were directed predominantly to linear epitopes poorly exposed on native gp120 and had more limited cross-recognition of divergent gp120. Fine epitope mapping revealed differences in antibody specificities. While both rgp120CM235 and rgp120SF2 induced antibodies to regions within C1, V1/V2, V3, and C5, unique responses were induced by rgp120CM235 to multiple epitopes within C2 and by rgp120SF2 to multiple epitopes within C3, V4, and C4. These data demonstrate that strain and/or phenotypic differences of HIV-1 subunit gp120 immunogens can substantially alter antibody binding specificities and subsequent HIV-1 neutralizing capacity.
authors.affiliation: Henry M. Jackson Foundation, Walter Reed Army Institute of Research, Rockville, Maryland 20850, USA. tvancott@hiv.hjf.org
authors.forename: T C
authors.initials: TC
authors.lastname: VanCott
authors.forename: J R
authors.initials: JR
authors.lastname: Mascola
authors.forename: L D
authors.initials: LD
authors.lastname: Loomis-Price
authors.forename: F
authors.initials: F
authors.lastname: Sinangil
authors.forename: N
authors.initials: N
authors.lastname: Zitomersky
authors.forename: J
authors.initials: J
authors.lastname: McNeil
authors.forename: M L
authors.initials: ML
authors.lastname: Robb
authors.forename: D L
authors.initials: DL
authors.lastname: Birx
authors.forename: S
authors.initials: S
authors.lastname: Barnett
mesh_terms: D016915:AIDS Vaccines / Q000276:immunology*; D000818:Animals; D018604:Epitope Mapping; D015483:HIV Antibodies / Q000097:blood*; D015699:HIV Envelope Protein gp120 / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D007114:Immunization; D010215:Papio; D011994:Recombinant Proteins / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology*
chemical_list: D016915:AIDS Vaccines; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic