title: Structure and immunogenicity of a peptide vaccine, including the complete HIV-1 gp41 2F5 epitope: implications for antibody recognition mechanism and immunogen design.
abstract: The membrane-proximal external region (MPER) of gp41 harbors the epitope recognized by the broadly neutralizing anti-HIV 2F5 antibody, a research focus in HIV-1 vaccine development. In this work, we analyze the structure and immunogenic properties of MPERp, a peptide vaccine that includes the following: (i) the complete sequence protected from proteolysis by the 2F5 paratope; (ii) downstream residues postulated to establish weak contacts with the CDR-H3 loop of the antibody, which are believed to be crucial for neutralization; and (iii) an aromatic rich anchor to the membrane interface. MPERp structures solved in dodecylphosphocholine micelles and 25% 1,1,1,3,3,3-hexafluoro-2-propanol (v/v) confirmed folding of the complete 2F5 epitope within continuous kinked helices. Infrared spectroscopy (IR) measurements demonstrated the retention of main helical conformations in immunogenic formulations based on alum, Freund's adjuvant, or two different types of liposomes. Binding to membrane-inserted MPERp, IR, molecular dynamics simulations, and characterization of the immune responses further suggested that packed helical bundles partially inserted into the lipid bilayer, rather than monomeric helices adsorbed to the membrane interface, could encompass effective MPER peptide vaccines. Together, our data constitute a proof-of-concept to support MPER-based peptides in combination with liposomes as stand-alone immunogens and suggest new approaches for structure-aided MPER vaccine development.
authors.affiliation: Institute of Physical Chemistry "Rocasolano," Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Serrano 119, E-28006 Madrid, Spain.
authors.forename: Soraya
authors.initials: S
authors.lastname: Serrano
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Aitziber
authors.initials: A
authors.lastname: Araujo
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Apellániz
authors.affiliation: Departments of Biochemistry, Medical Biophysics, and Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada; The Campbell Family Institute for Cancer Research, Ontario Cancer Institute/University Health Network, Toronto, Ontario M5G 1L7, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: Bryson
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Carravilla
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Igor
authors.initials: I
authors.lastname: de la Arada
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Nerea
authors.initials: N
authors.lastname: Huarte
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Edurne
authors.initials: E
authors.lastname: Rujas
authors.affiliation: Departments of Biochemistry, Medical Biophysics, and Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada; The Campbell Family Institute for Cancer Research, Ontario Cancer Institute/University Health Network, Toronto, Ontario M5G 1L7, Canada.
authors.forename: Emil F
authors.initials: EF
authors.lastname: Pai
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: José L R
authors.initials: JLR
authors.lastname: Arrondo
authors.affiliation: Chemistry Research Laboratory, Mansfield Road, University of Oxford, Oxford OX1 3TA, United Kingdom; Department of Chemistry, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: Carmen
authors.initials: C
authors.lastname: Domene
authors.affiliation: Institute of Physical Chemistry "Rocasolano," Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Serrano 119, E-28006 Madrid, Spain. Electronic address: majimenez@iqfr.csic.es.
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Jiménez
authors.affiliation: Biophysics Unit, Consejo Superior de Investigaciones Científicas and University of the Basque Country (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P. O. Box 644, 48080 Bilbao, Spain. Electronic address: gbpniesj@lg.ehu.es.
authors.forename: José L
authors.initials: JL
authors.lastname: Nieva
mesh_terms: D016915:AIDS Vaccines / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology*; D000080908:Broadly Neutralizing Antibodies; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes / Q000737:chemistry / Q000276:immunology*; D008823:Micelles; D008969:Molecular Sequence Data; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013055:Spectrophotometry, Infrared; D022223:Vaccines, Subunit / Q000737:chemistry / Q000378:metabolism
chemical_list: C558560:2F5 monoclonal antibody; D016915:AIDS Vaccines; D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000080908:Broadly Neutralizing Antibodies; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D016056:Immunodominant Epitopes; D008823:Micelles; D022223:Vaccines, Subunit; D010767:Phosphorylcholine; C028810:dodecylphosphocholine
keywords: Fourier Transform IR (FTIR); HIV-1; Liposomes; Nuclear Magnetic Resonance; Peptide Conformation; Vaccine Development