title: Isolation of human monoclonal antibodies to the envelope e2 protein of hepatitis C virus and their characterization.
abstract: We isolated and characterized two human monoclonal antibodies to the envelope E2 protein of hepatitis C virus (HCV). Lymphoblastoid cell lines stably producing antibodies were obtained by immortalizing peripheral blood mononuclear cells of a patient with chronic hepatitis C using Epstein-Barr virus. Screening for antibody-positive clones was carried out by immunofluorescence with Huh7 cells expressing the E2 protein of HCV strain H (genotype 1a) isolated from the same patient. Isotype of resulting antibodies, #37 and #55, was IgG1/kappa and IgG1/lambda, respectively. Epitope mapping revealed that #37 and #55 recognize conformational epitopes spanning amino acids 429 to 652 and 508 to 607, respectively. By immunofluorescence using virus-infected Huh7.5 cells as targets both antibodies were reactive with all of the nine different HCV genotypes/subtypes tested. The antibodies showed a different pattern of immuno-staining; while #37 gave granular reactions mostly located in the periphery of the nucleus, #55 gave diffuse staining throughout the cytoplasm. Both antibodies were shown by immuno-gold electron microscopy to bind to intact viral particles. In a neutralization assay (focus-forming unit reduction using chimeric infectious HCV containing structural proteins derived from genotypes 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a, and 7a), #55 inhibited the infection of all HCV genotypes tested but genotype 7a to a lesser extent. #37 did not neutralize any of these viruses. As a broadly cross-neutralizing human antibody, #55 may be useful for passive immunotherapy of HCV infection.
authors: Division of Microbiology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, Kobe, Japan. yshimizu@nih.go.jp
authors: Yohko K
authors: YK
authors: Shimizu
authors: Minako
authors: M
authors: Hijikata
authors: Masamichi
authors: M
authors: Oshima
authors: Kazufumi
authors: K
authors: Shimizu
authors: Harvey J
authors: HJ
authors: Alter
authors: Robert H
authors: RH
authors: Purcell
authors: Hiroshi
authors: H
authors: Yoshikura
authors: Hak
authors: H
authors: Hotta
mesh_terms: D000595:Amino Acid Sequence; D019138:Antibodies, Blocking / Q000276:immunology / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000915:Antibody Affinity / Q000276:immunology; D000956:Antigens, Viral / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D002461:Cell Line, Transformed; D003429:Cross Reactions / Q000276:immunology; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D021381:Protein Transport; D016415:Sequence Alignment; D014759:Viral Envelope Proteins / Q000276:immunology* / Q000378:metabolism; D014771:Virion / Q000276:immunology / Q000648:ultrastructure
chemical_list: D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D000939:Epitopes; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D014759:Viral Envelope Proteins