HEPATITIS-C VIRUS TYPE-7, TYPE-8 AND TYPE-9 SHOULD BE CLASSIFIED AS TYPE-6 SUBTYPES

Tokita et al, reported the identification of hepatitis C virus type 7, 8 and 9 in Southeast Asia, based on the unweighed pair-group method w ith the arithmetic mean, a method that may not be appropriate when the nucleotide suibstitution rate is not constant over time, To determine more accurately the relationship of these proposed types 7, 8, and 9 with other types, a more appropriate approach, the neighbor-joining me thod, was applied to re-evaluate the phylogenetic relationship. A tota l of 660 HCV sequences, including the reported sequences, were collect ed from DNA databases, For every region, the nucleotide substitution r ate was estimated by the 6-parameter method, and phylogenetic trees we re constructed using the neighbor-joining method, The results of this analysis indicate that the newly proposed HCV types 7, 8 and 9 should be classified as type 6 subtypes, HCV type 6 appears to be diversified .