Genotypes of hepatitis C virus isolates from different parts of the world

Hepatitis C virus (HCV) causes most cases of posttransfusion non-A, non-B hepatitis. HCV isolates were classified by their genetic relatedness into at least six genotypes and a series of subtypes. Methods for typing included amplification of certain genomic regions using universal or type/subtype specific primers, restriction fragment length polymorphism analysis, differential hybridization, nucleotide sequencing, and serologic genotyping. HCV genotypes and their subtypes coexist in various geographic locations but show different prevalences. The identification of genotypes/subtypes is useful for studies on the molecular epidemiology and pathogenesis of HCV infection.