Hepatitis C virus (HCV) is a leading cause of chronic viral
hepatitis worldwide. The study of antibody-mediated virus neutralization has been hampered by the lack of an efficient and high-throughput cell culture system for the study of virus neutralization. The HCV structural
proteins have been shown to assemble into noninfectious HCV-like particles (HCV-LPs). Similar to serum-derived virions, HCV-LPs bind and enter human hepatocytes and
hepatoma cell lines. In this study, we developed an HCV-LP-based model system for a systematic functional analysis of
antiviral antibodies from patients with acute or
chronic hepatitis C. We demonstrate that cellular HCV-LP binding was specifically inhibited by
antiviral antibodies from patients with acute or
chronic hepatitis C in a dose-dependent manner. Using a library of homologous overlapping envelope
peptides covering the entire HCV envelope, we identified an
epitope in the N-terminal E2 region (SQKIQLVNTNGSWHI;
amino acid positions 408 to 422) as one target of human
antiviral antibodies inhibiting cellular particle binding. Using a large panel of serum samples from patients with acute and
chronic hepatitis C, we demonstrated that the presence of
antibodies with inhibition of binding activity was not associated with viral clearance. In conclusion, antibody-mediated inhibition of cellular HCV-LP binding represents a convenient system for the functional characterization of human
anti-HCV antibodies, allowing the mapping of envelope neutralization
epitopes targeted by naturally occurring
antiviral antibodies.