USE OF NS-4 PEPTIDES TO IDENTIFY TYPE-SPECIFIC ANTIBODY TO HEPATITIS-C VIRUS GENOTYPE-1, GENOTYPE-2, GENOTYPE-3, GENOTYPE-4, GENOTYPE-5 ANDGENOTYPE-6

The 5' end of the NS-4 protein of different genotypes of hepatitis C v irus (HCV) is highly variable in nucleotide and inferred amino acid se quence, with frequent predicted amino acid substitutions between all s ix of the major HCV genotypes described to date. This region has been shown to be antigenic by epitope mapping, and elicits antibody in HCV- infected individuals with a detectable type-specific component. We hav e used this sequence data to specify branched peptides for an indirect binding/competition assay to detect type-specific antibody to each ma jor genotype. A total of 183 out of 210 samples (87%) from blood donor s and patients with chronic hepatitis C infected with genotypes 1 to 6 showed detectable type-specific antibody to NS-4 peptides that in alm ost all cases (> 97%) corresponded to the genotype detected by a PCR t yping method. These findings demonstrate the existence of major antige nic differences between genotypes of HCV, and indicate how infection w ith different variants of HCV may be detected by a serological test.