Cocrystal Structures of Antibody N60-i3 and Antibody JR4 in Complex with gp120 Define More Cluster A Epitopes Involved in Effective Antibody-Dependent Effector Function against HIV-1.
Accumulating evidence indicates a role for Fc receptor (FcR)-mediated effector functions of antibodies, including antibody-dependent cell-mediated cytotoxicity (ADCC), in prevention of human immunodeficiency virus type 1 (HIV-1) acquisition and in po ...
Accumulating evidence indicates a role for Fc receptor (FcR)-mediated effector functions of antibodies, including antibody-dependent cell-mediated cytotoxicity (ADCC), in prevention of human immunodeficiency virus type 1 (HIV-1) acquisition and in postinfection control of viremia. Consequently, an understanding of the molecular basis for Env epitopes that constitute effective ADCC targets is of fundamental interest for humoral anti-HIV-1 immunity and for HIV-1 vaccine design. A substantial portion of FcR effector function of potentially protective anti-HIV-1 antibodies is directed toward nonneutralizing, transitional, CD4-inducible (CD4i) epitopes associated with the gp41-reactive region of gp120 (cluster A epitopes). Our previous studies defined the A32-like epitope within the cluster A region and mapped it to the highly conserved and mobile layers 1 and 2 of the gp120 inner domain within the C1-C2 regions of gp120. Here, we elucidate additional cluster A epitope structures, including an A32-like epitope, recognized by human monoclonal antibody (MAb) N60-i3, and a hybrid A32-C11-like epitope, recognized by rhesus macaque MAb JR4. These studies define for the first time a hybrid A32-C11-like epitope and map it to elements of both the A32-like subregion and the seven-layered β-sheet of the gp41-interactive region of gp120. These studies provide additional evidence that effective antibody-dependent effector function in the cluster A region depends on precise epitope targeting--a combination of epitope footprint and mode of antibody attachment. All together these findings help further an understanding of how cluster A epitopes are targeted by humoral responses.
Organizational Affiliation:
Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Medical Care Clinical Center, VA Maryland Health Care Center, Baltimore, Maryland, USA.,Department of Pediatrics, Tulane University Medical Center, New Orleans, Louisiana, USA.,Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA mpazgier@ihv.umaryland.edu.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA.,CEA, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette, France.,Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.
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