Human monoclonal antibodies for the immunological characterization of a highly conserved protein domain of the hepatitis C virus glycoprotein E1

• Published in: Clinical and experimental immunology Vol. 101; no. 2; pp. 278 - 283
• Main Authors: SIEMONEIT, K., CARDOSO, M. DA SILVA, KOERNER, K., WÖLPL, A., KUBANEK, B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.1995; Blackwell
• Subjects: Amino Acid Sequence; Antibodies, Monoclonal - immunology; Antibody Specificity; Antigenic determinants, haptens, artificial antigens; Antigens; B-Lymphocytes - drug effects; B-Lymphocytes - immunology; Biological and medical sciences; Conserved Sequence; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Hepatitis Antibodies - blood; Hepatitis Antibodies - immunology; Hepatitis C - blood; Hepatitis C Antibodies; Hepatitis C virus; human monoclonal antibodies; Humans; Immunoblotting; Immunoglobulin G - immunology; Leukocytes, Mononuclear - immunology; Lymphocyte Activation - immunology; Molecular immunology; Molecular Sequence Data; Peptide Fragments - immunology; Viral Envelope Proteins - immunology; Virus; Human; Conserved sequence; Synthetic product; Domain structure; Glycoproteins; Monoclonal antibody; Flaviviridae; Hepatitis C virus; Humoral immunity
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.1995.tb08351.x

SUMMARY Although both envelope glycoproteins of the hepatitis C virus, E1 and E2/NS1, show a high degree of sequence variation, the E1 protein includes a well conserved domain, which may be functionally important. We have analysed the human B cell response to a peptide fragment from amino acid residues 314–330 (EP3) covering the central conserved sequence of this domain. Anti‐hepatitis C virus‐positive blood donors were screened for anti‐EP3 antibodies with an ELISA based on immobilized peptide. Thirty out of 92 (32%) RIBA‐confirmed donors displayed a significant antibody response to EP3. From three of these blood donors we established four anti‐EP3‐producing heterohybridoma cell lines: U1/F30 and U1/F31 produced IgM‐κ, whereas U1/F32 and U1/F33 secreted the isotypes IgG1‐λ and IgG1‐κ, respectively. Epitope analysis with overlapping nonapeptides suggests the existence of different antigenic determinants within the EP3 fragment. Although both IgG antibodies U1/F32 and U1/F33 have dissociation constants to the peptide of ∼ 10−9 M, binding to recombinant E1 protein expressed in COS‐7 cells was different. Only U1/F33 detected envelope protein of ∼ 24–35 kD in Western blot. This human MoAb will be useful for further investigations on the hepatitis C virus glycoprotein E1.