Sequence analysis of hepatitis C virus genotypes 1 to 5 reveals multiple novel subtypes in the Benelux countries.

Hepatitis C virus (HCV) isolates from a cohort of 315 patients from the Benelux countries (Belgium, The Netherlands, Luxembourg) were genotyped by means of reverse hybridization Inno-LiPA (line probe assay). Genotypes 1a, 1b, 2a, 2b, 3a, 4a and 5a were detected. From the cohort, isolates representing all types and those showing an aberrant LiPA pattern were further analysed by sequencing parts of the 5' UTR, core (nt 1 to 326; aa residues 1 to 108) and core/E1 (nt 477 to 924; aa residues 159 to 308) regions. Molecular evolutionary analysis of the core and core/E1 regions allowed discrimination between known and additional subtypes, especially within types 2 and 4. The core region is not suitable for classification of new subtypes because of the relatively high level of conservation. The core/E1 region displays a higher level of sequence variation and allows much more distinct discrimination between subtypes. Genotypes 2 and 4 are particularly heterogeneous, with at least 7 and 10 subtypes, respectively. In contrast to previous reports from Europe, HCV isolates from the cohort constituted a highly heterogeneous population of virus variants, especially within genotypes 2 and 4.