title: Structure and Recognition of a Novel HIV-1 gp120-gp41 Interface Antibody that Caused MPER Exposure through Viral Escape.
abstract: A comprehensive understanding of the regions on HIV-1 envelope trimers targeted by broadly neutralizing antibodies may contribute to rational design of an HIV-1 vaccine. We previously identified a participant in the CAPRISA cohort, CAP248, who developed trimer-specific antibodies capable of neutralizing 60% of heterologous viruses at three years post-infection. Here, we report the isolation by B cell culture of monoclonal antibody CAP248-2B, which targets a novel membrane proximal epitope including elements of gp120 and gp41. Despite low maximum inhibition plateaus, often below 50% inhibitory concentrations, the breadth of CAP248-2B significantly correlated with donor plasma. Site-directed mutagenesis, X-ray crystallography, and negative-stain electron microscopy 3D reconstructions revealed how CAP248-2B recognizes a cleavage-dependent epitope that includes the gp120 C terminus. While this epitope is distinct, it overlapped in parts of gp41 with the epitopes of broadly neutralizing antibodies PGT151, VRC34, 35O22, 3BC315, and 10E8. CAP248-2B has a conformationally variable paratope with an unusually long 19 amino acid light chain third complementarity determining region. Two phenylalanines at the loop apex were predicted by docking and mutagenesis data to interact with the viral membrane. Neutralization by CAP248-2B is not dependent on any single glycan proximal to its epitope, and low neutralization plateaus could not be completely explained by N- or O-linked glycosylation pathway inhibitors, furin co-transfection, or pre-incubation with soluble CD4. Viral escape from CAP248-2B involved a cluster of rare mutations in the gp120-gp41 cleavage sites. Simultaneous introduction of these mutations into heterologous viruses abrogated neutralization by CAP248-2B, but enhanced neutralization sensitivity to 35O22, 4E10, and 10E8 by 10-100-fold. Altogether, this study expands the region of the HIV-1 gp120-gp41 quaternary interface that is a target for broadly neutralizing antibodies and identifies a set of mutations in the gp120 C terminus that exposes the membrane-proximal external region of gp41, with potential utility in HIV vaccine design.
authors.affiliation: Centre for HIV and STIs, National Institute for Communicable Diseases (NICD), of the National Health Laboratory Service (NHLS), Johannesburg, South Africa.|Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Constantinos Kurt
authors.identifier: 0000-0003-2329-2280
authors.initials: CK
authors.lastname: Wibmer
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Jason
authors.identifier: 0000-0002-3775-6560
authors.initials: J
authors.lastname: Gorman
authors.affiliation: Department of Integrative Structural and Computational Biology, CHAVI-ID, IAVI Neutralizing Antibody Center and Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Gabriel
authors.identifier: 0000-0002-9695-8138
authors.initials: G
authors.lastname: Ozorowski
authors.affiliation: Centre for HIV and STIs, National Institute for Communicable Diseases (NICD), of the National Health Laboratory Service (NHLS), Johannesburg, South Africa.|Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Jinal N
authors.identifier: 0000-0001-6354-4003
authors.initials: JN
authors.lastname: Bhiman
authors.affiliation: Institute of Infectious Disease and Molecular Medicine (IDM) and Division of Medical Virology, University of Cape Town and NHLS, Cape Town, South Africa.
authors.forename: Daniel J
authors.identifier: 0000-0002-0227-5636
authors.initials: DJ
authors.lastname: Sheward
authors.affiliation: Department of Pediatrics, Tulane University Medical Center, New Orleans, Louisiana, United States of America.
authors.forename: Debra H
authors.initials: DH
authors.lastname: Elliott
authors.affiliation: Department of Pediatrics, Tulane University Medical Center, New Orleans, Louisiana, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Rouelle
authors.affiliation: Department of Pediatrics, Tulane University Medical Center, New Orleans, Louisiana, United States of America.
authors.forename: Ashley
authors.initials: A
authors.lastname: Smira
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: M Gordon
authors.identifier: 0000-0002-6808-7232
authors.initials: MG
authors.lastname: Joyce
authors.affiliation: Institute of Infectious Disease and Molecular Medicine (IDM) and Division of Medical Virology, University of Cape Town and NHLS, Cape Town, South Africa.
authors.forename: Nonkululeko
authors.initials: N
authors.lastname: Ndabambi
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Aliaksandr
authors.initials: A
authors.lastname: Druz
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Mangai
authors.identifier: 0000-0002-2125-3010
authors.initials: M
authors.lastname: Asokan
authors.affiliation: Department of Immunology and Microbial Science, CHAVI-ID and IAVI Neutralizing Antibody Centre, The Scripps Research Institute, La Jolla, California, United States of America.|Ragon Institute of Massachusetts General Hospital, MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Dennis R
authors.identifier: 0000-0001-6711-9864
authors.initials: DR
authors.lastname: Burton
authors.affiliation: Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Mark
authors.identifier: 0000-0002-2108-8705
authors.initials: M
authors.lastname: Connors
authors.affiliation: Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa.|Department of Epidemiology, Columbia University, New York, New York, United States of America.
authors.forename: Salim S
authors.identifier: 0000-0002-4986-2133
authors.initials: SS
authors.lastname: Abdool Karim
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: John R
authors.identifier: 0000-0002-5293-4695
authors.initials: JR
authors.lastname: Mascola
authors.affiliation: Department of Pediatrics, Tulane University Medical Center, New Orleans, Louisiana, United States of America.
authors.forename: James E
authors.identifier: 0000-0002-9215-9523
authors.initials: JE
authors.lastname: Robinson
authors.affiliation: Department of Integrative Structural and Computational Biology, CHAVI-ID, IAVI Neutralizing Antibody Center and Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Andrew B
authors.identifier: 0000-0002-5302-5899
authors.initials: AB
authors.lastname: Ward
authors.affiliation: Institute of Infectious Disease and Molecular Medicine (IDM) and Division of Medical Virology, University of Cape Town and NHLS, Cape Town, South Africa.|Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Williamson
authors.affiliation: Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Peter D
authors.identifier: 0000-0003-3560-232X
authors.initials: PD
authors.lastname: Kwong
authors.affiliation: Centre for HIV and STIs, National Institute for Communicable Diseases (NICD), of the National Health Laboratory Service (NHLS), Johannesburg, South Africa.|Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.|Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Lynn
authors.identifier: 0000-0002-1836-8415
authors.initials: L
authors.lastname: Morris
authors.affiliation: Centre for HIV and STIs, National Institute for Communicable Diseases (NICD), of the National Health Laboratory Service (NHLS), Johannesburg, South Africa.|Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.|Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Penny L
authors.initials: PL
authors.lastname: Moore
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000302:isolation & purification / Q000648:ultrastructure; D057134:Antibodies, Neutralizing / Q000276:immunology* / Q000302:isolation & purification; D001666:Binding Sites, Antibody / Q000235:genetics* / Q000276:immunology; D015704:CD4 Antigens / Q000494:pharmacology; D045744:Cell Line, Tumor; D022801:Complementarity Determining Regions / Q000235:genetics; D018360:Crystallography, X-Ray; D000939:Epitopes / Q000276:immunology; D006031:Glycosylation; D015483:HIV Antibodies / Q000276:immunology* / Q000302:isolation & purification; D015488:HIV Antigens / Q000235:genetics / Q000276:immunology / Q000648:ultrastructure*; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000235:genetics / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D057131:Immune Evasion / Q000235:genetics* / Q000276:immunology; D009500:Neutralization Tests; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D015704:CD4 Antigens; D022801:Complementarity Determining Regions; D000939:Epitopes; D015483:HIV Antibodies; D015488:HIV Antigens; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D011994:Recombinant Proteins; C076613:recombinant soluble CD4