Serological differentiation between HCV subtypes 1a and 1b by a recombinant immunoblot assay.

Until now, no serological assay has been available for the differentiation of HCV subtypes. Since there is evidence that the subtypes differently influence the clinical course of HCV infection and the outcome of interferon therapy, we established a strip immunoblot assay (NS-4 IBA) with recombinant HCV proteins of the nonstructural 4 (NS-4) region propagated in Escherichia coli. Using this NS-4 IBA, we were able to distinguish HCV subtypes 1a and 1b, which are the most prevalent subtypes in Europe and the U.S.A. The results of the serotyping assay were compared with those obtained by nucleotide sequencing from the NS-5 region. Concordant results were observed to match 94.9% (n=100) by the NS-4 IBA and nucleotide sequencing. Discrepant results were obtained in only 5.1% (n=6). These data indicate that HCV subtypes can be serologically distinguished, providing the possibility for easier identification of infection with different HCV subtypes.