Discrepancy of hepatitis C virus genotypes as determined by phylogenetic analysis of partial NS5 and core sequences

The use of phylogenetic analyses of partial NS5 and core regions for hepatitis C virus (HCV) genotyping was evaluated by analysing seven Honduran and 24 European HCV strains. Core primers were designed with which HCV genotypes 1, 2, and 3 were readily amplified. The reliability of phylogenetic analysis of a 111-bp core sequence was verified by comparing the typing results with those obtained using the whole core gene of 52 reference strains. Accordant genotypes (1a, 1b, 2b, and 3a) were obtained when phylogenetic analyses were undertaken on both the partial core and a 222-bp NS5 sequence in all of the European HCV strains. Genotypes 1a, 1b, and 3a were identified among the Honduran strains by phylogenetic analysis of the partial NS5 sequence. Interestingly, two of three Honduran type 3a strains, as determined by the NS5 sequence analysis, turned out to be type 1a by core sequence analysis. These two strains were also classified as type 1a, but not 3a, by a core type-specific PCR. Furthermore, the E2/NS1 regions were similar to HCV-PT, a representative strain of genotype 1a. The results indicate that chimeral HCV strains exist, although in most cases a good concordance is found when phylogenetic analysis of partial core and NS5 sequences are used for genotyping. This finding should be taken into account when HCV is genotyped by phylogenetic analysis of a partial HCV sequence from a single genomic region.