Hepatitis C virus (HCV) is the predominant agent of blood transfusion-transmitted non-A non-B hepatitis. A study of epitope-based synthetic antigens for prevention or amelioration of HCV infection is proposed here. These immunogens would be made by synthesizing peptide epitopes on an innovative 8-branched peptide carrier. Potentially protective peptides to be carried by this octameric peptide system would be selected from over 200 HCV synthetic peptides according to their reactivities with serum samples from patients who have acquired natural immunity. The study is expected to demonstrate that such artificial HCV antigens can elicit long-term antibody responses in guinea pigs. The eight-branched core structure carrier system is expected to render the immunogens, which have been selected by precise epitope-directed serological validation and from which deleterious or extraneous sequences have been omitted, highly antigenic due to the high effective concentration of protective determinants presented to the immune system. A vaccine for hepatitis C would be the final application of this research proposal. Biologicals for the treatment of HCV infection may also be generated by this project.