IMMUNOASSAYS TO STUDY PREVALENCE OF ANTIBODY AGAINST GB-VIRUS-C IN BLOOD-DONORS

Immunoassays were developed to determine the seroprevalence of antibod y against human GB virus C (GBV-C). The antigenic target in each assay was a 44.6-kDa glycosylated protein representing the first 315 amino acids encoded by the GBV-C E2 gene. Sera or plasma were assayed for E2 antibody using an anti-human EIA format in which antigen-coated polys tyrene beads were reacted with sample, and bound antibody was detected by addition of enzyme labelled goat anti-human IgG. The presence of a nti-E2 antibody was conformed using a sandwich EIA format in which sam ples were reacted with antigen coated polystyrene beads, followed by a ddition of solution phase biotinylated antigen. Detection of antibody captured biotinylated E2 was accomplished by addition of enzyme-conjug ated anti-biotin antibody. Antibody against the E2 antigen was detecte d in 7.4 and 7.8% of 500 sera and 500 plasma, respectively, from US vo lunteers donating to a Wisconsin blood center, and in approximately 10 .7% of hepatitis and retrovirus marker-negative volunteer blood donors from a Missouri blood center. The rate in 1018 sera from US commercia l donors at multiple US blood centers was 36.7%. These results indicat ed a relatively high prevalence of GBV-C exposure in US volunteer dono rs, and particularly in commercial donors. The clinical implication of the high exposure rate is unclear. These immunoassays are being combi ned with nucleic acid detection to assess prevalence of GBV-C world wi de and to determine if GBV-C plays a role as an etiologic agent. (C) 1 997 Elsevier Science B.V.