CHARACTERIZATION OF HUMAN MONOCLONAL-ANTIBODIES SPECIFIC TO THE HEPATITIS-C VIRUS GLYCOPROTEIN E2 WITH IN-VITRO BINDING NEUTRALIZATION PROPERTIES

Both linear and conformational determinants of hepatitis C virus (HCV) are believed to be involved in viral neutralization. After immortaliz ation of B cells from HCV chronically infected patients with Epstein-B arr virus, we obtained two polyclonal lymphoblastoid cell lines (LCL) secreting human monoclonal antibodies (HMabs). One clone was derived f rom a patient infected with a genotype 4 isolate while the second was isolated from a genotype Ib-infected patient. Immunoprecipitation stud ies, Western blot, and immunofluorescence analysis, peptide scanning, and ELISA studies indicated that the HMabs (1) recognized conformation -dependent determinant(s), (2) were capable of recognizing genotype la and Ib derived antigens, and (3) were able to precipitate noncovalent ly associated E1 E2 complexes believed to exist on the surface of viri on particles. The HMab derived from the genotype LF-infected patient w as in addition shown to neutralize the in vitro binding of recombinant E2 protein onto susceptible cells suggesting a potential for in vivo neutralization. These data indicate that anti-E2 antibodies directed a t conserved conformational-dependent determinant(s) exist in chronic H CV infection. (C) 1998 Academic Press.