Isolation of human monoclonal antibodies to the envelope e2 protein of hepatitis C virus and their characterization

• Published in: PloS one Vol. 8; no. 2; p. e55874
• Main Authors: Shimizu, Yohko K, Hijikata, Minako, Oshima, Masamichi, Shimizu, Kazufumi, Alter, Harvey J, Purcell, Robert H, Yoshikura, Hiroshi, Hotta, Hak
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.02.2013; Public Library of Science (PLoS)
• Subjects: Amino Acid Sequence; Amino acids; Antibodies, Blocking - immunology; Antibodies, Blocking - metabolism; Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - genetics; Antibodies, Monoclonal - immunology; Antibodies, Neutralizing; Antibodies, Viral - chemistry; Antibodies, Viral - genetics; Antibodies, Viral - immunology; Antibody Affinity - immunology; Antigen-antibody reactions; Antigenic determinants; Antigens, Viral - chemistry; Antigens, Viral - immunology; Antigens, Viral - metabolism; Biology; Cell culture; Cell Line, Transformed; Cloning; Cross Reactions - immunology; Cytoplasm; E2 protein; Electron microscopy; Epitope Mapping; Epitopes - chemistry; Epitopes - immunology; Epstein-Barr virus; Genetic aspects; Genotype; Genotype & phenotype; Genotypes; Glycoproteins; Gold; Health aspects; Hepacivirus - genetics; Hepacivirus - immunology; Hepatitis; Hepatitis C; Hepatitis C virus; Humans; Immunofluorescence; Immunoglobulin G; Immunoglobulin G - chemistry; Immunoglobulin G - genetics; Immunoglobulin G - immunology; Immunoglobulin Heavy Chains - chemistry; Immunoglobulin Heavy Chains - genetics; Immunoglobulins; Immunotherapy; Infections; Infectious diseases; Leukocytes (mononuclear); Lymphoblastoid cell lines; Lymphocytes - immunology; Lymphocytes - metabolism; Medicine; Molecular Sequence Data; Monoclonal antibodies; Mutation; Neutralization; Neutralization Tests; Nuclei; Peripheral blood mononuclear cells; Protein Transport; Proteins; Sequence Alignment; Staining; Structural proteins; Viral Envelope Proteins - immunology; Viral Envelope Proteins - metabolism; Virion - immunology; Virion - ultrastructure; Viruses; United States > US; Maryland; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0055874

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.