Geographical distribution of hepatitis C virus genotypes in India.

HCV isolates from around the world show substantial nucleotide sequence variability throughout the viral genome. Based on the identification of these genome differences various genotypes and subtypes have been described from different geographical regions. They have been tentatively classified into six major genotypes and more than 30 subtypes, but new subtypes are continually being discovered. In recent years, substantial evidence has emerged indicating that typing and subtyping for HCV is clinically important. The present study aims at determining and comparing the prevalence of different genotypes from different parts of India (North, South, East and West). A total of 153 samples representing different regions have been genotyped in our lab. Our studies document a high prevalence of genotype 3 (> 76%) and very low prevalence of genotype 2 (< 2%), as a whole. However, genotype 3a has been found to be the highest (50%) with a decreased frequency of approximately 25% in the case of 3b, approximately 14% in 1b and approximately 10% in 1a, whereas a minimal number (approximately 4%) of genotype 4 has been found only in Southern and Western India.