title: A fusion intermediate gp41 immunogen elicits neutralizing antibodies to HIV-1.
abstract: The membrane-proximal external region (MPER) of the human immunodeficiency virus, type 1 (HIV-1) envelope glycoprotein subunit gp41 is targeted by potent broadly neutralizing antibodies 2F5, 4E10, and 10E8. These antibodies recognize linear epitopes and have been suggested to target the fusion intermediate conformation of gp41 that bridges viral and cellular membranes. Anti-MPER antibodies exert different degrees of membrane interaction, which is considered to be the limiting factor for the generation of such antibodies by immunization. Here we characterize a fusion intermediate conformation of gp41 (gp41(int)-Cys) and show that it folds into an elongated ∼ 12-nm-long extended structure based on small angle x-ray scattering data. Gp41(int)-Cys was covalently linked to liposomes via its C-terminal cysteine and used as immunogen. The gp41(int)-Cys proteoliposomes were administered alone or in prime-boost regimen with trimeric envelope gp140(CA018) in guinea pigs and elicited high anti-gp41 IgG titers. The sera interacted with a peptide spanning the MPER region, demonstrated competition with broadly neutralizing antibodies 2F5 and 4E10, and exerted modest lipid binding, indicating the presence of MPER-specific antibodies. Although the neutralization potency generated solely by gp140(CA018) was higher than that induced by gp41(int)-Cys, the majority of animals immunized with gp41(int)-Cys proteoliposomes induced modest breadth and potency in neutralizing tier 1 pseudoviruses and replication-competent simian/human immunodeficiency viruses in the TZM-bl assay as well as responses against tier 2 HIV-1 in the A3R5 neutralization assay. Our data thus demonstrate that liposomal gp41 MPER formulation can induce neutralization activity, and the strategy serves to improve breadth and potency of such antibodies by improved vaccination protocols.
authors.affiliation: From the Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Rachel P J
authors.initials: RP
authors.lastname: Lai
authors.affiliation: Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), F-38000 Grenoble, France, CNRS, UVHCI, F-38000 Grenoble, France.
authors.forename: Miriam
authors.initials: M
authors.lastname: Hock
authors.affiliation: Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), F-38000 Grenoble, France, CNRS, UVHCI, F-38000 Grenoble, France.
authors.forename: Jens
authors.initials: J
authors.lastname: Radzimanowski
authors.affiliation: From the Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Tonks
authors.affiliation: Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), F-38000 Grenoble, France, CNRS, UVHCI, F-38000 Grenoble, France.
authors.forename: David Lutje
authors.initials: DL
authors.lastname: Hulsik
authors.affiliation: Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), F-38000 Grenoble, France, CNRS, UVHCI, F-38000 Grenoble, France.
authors.forename: Gregory
authors.initials: G
authors.lastname: Effantin
authors.affiliation: From the Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Seilly
authors.affiliation: From the Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Hanna
authors.initials: H
authors.lastname: Dreja
authors.affiliation: Institute of Medical Microbiology and Hygiene, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kliche
authors.affiliation: Institute of Medical Microbiology and Hygiene, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Wagner
authors.affiliation: Novartis Vaccines and Diagnostics Inc., Cambridge, Massachusetts 02139.
authors.forename: Susan W
authors.initials: SW
authors.lastname: Barnett
authors.affiliation: National Institute for Communicable Diseases, Centre for HIV and Sexually Transmitted Infections, 1 Modderfontein Road, Sandringham 2131, South Africa.
authors.forename: Nancy
authors.initials: N
authors.lastname: Tumba
authors.affiliation: National Institute for Communicable Diseases, Centre for HIV and Sexually Transmitted Infections, 1 Modderfontein Road, Sandringham 2131, South Africa.
authors.forename: Lynn
authors.initials: L
authors.lastname: Morris
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, and.
authors.forename: Celia C
authors.initials: CC
authors.lastname: LaBranche
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, and.
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.affiliation: Division of Viral Pathogenesis, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Seaman
authors.affiliation: From the Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom, jlh66@cam.ac.uk.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Heeney
authors.affiliation: Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), F-38000 Grenoble, France, CNRS, UVHCI, F-38000 Grenoble, France, weissenhorn@embl.fr.
authors.forename: Winfried
authors.initials: W
authors.lastname: Weissenhorn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000915:Antibody Affinity / Q000276:immunology; D005260:Female; D006168:Guinea Pigs; D015483:HIV Antibodies / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology; D008969:Molecular Sequence Data; D033363:Neutron Diffraction; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000378:metabolism / Q000648:ultrastructure; D053838:Scattering, Small Angle
chemical_list: D057134:Antibodies, Neutralizing; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D007106:Immune Sera; D007074:Immunoglobulin G; D011510:Proteolipids; C020485:proteoliposomes
keywords: AIDS; HIV-1; HIV-1 gp41; Membrane Fusion; Protein Conformation; Vaccine Development; X-ray Scattering