SIGNIFICANCE OF SPECIFIC ANTIBODY-ASSAY FOR GENOTYPING OF HEPATITIS-CVIRUS

Group I and II hepatitis C virus genotypes were determined by a newly developed serological genotyping assay. This assay detected antibodies against group-specific recombinant proteins in the putative NS4 prote in region (amino acid no. 1676-1760) by an enzyme-linked immunosorbent assay. This region of the hepatitis C virus peptide has many group-sp ecific amino acids; fewer than 50% of these amino acids are identical between groups I and II. Genotypes determined by the serological genot yping assay were compared with those determined by a method in which t he polymerase chain reaction was used in 91 chronic hepatitis patients . The group specific polymerase chain reaction was performed within th e genome region corresponding to the putative NS5 protein, where the g roup II hepatitis C virus genome is 57 nucleotides longer than that of group I. Among 91 chronic hepatitis C patients who had positive resul ts in the second-generation hepatitis C virus antibody (core and NS3 r egion) assay, hepatitis C virus RNA was detected in 80 patients by pol ymerase chain reaction in the 5' untranslated region and in 78 patient s by this group-specific polymerase chain reaction. As a result, in 76 of 91 patients (84%) genotypes determined by the serological genotypi ng assay showed complete agreement with those determined by the group- specific polymerase chain reaction, and none of the patients revealed a group opposite to that of hepatitis C virus genotype. The detection rate of the serological genotyping assay (89 of 91; 98%) was even high er than that of the polymerase chain reaction assay (78 of 91; 86%). T hus, serological genotyping assay is specific and sensitive for the de termination of hepatitis C virus genotypes, and this enzyme-linked imm unosorbent assay may be useful for epidemiological studies of hepatiti s C virus genotypes.