Complete genome of a European hepatitis C virus subtype Ig isolate:: phylogenetic and genetic analyses

Background: Hepatitis C virus isolates have been classified into six main genotypes and a variable number of subtypes within each genotype, mainly based on phylogenetic analysis. Analyses of the genetic relationship among genotypes and subtypes are more reliable when complete genome sequences ( or at least the full coding region) are used; however, so far 31 of 80 confirmed or proposed subtypes have at least one complete genome available. Of these, 20 correspond to confirmed subtypes of epidemic interest. Results: We present and analyse the first complete genome sequence of a HCV subtype Ig isolate. Phylogenetic and genetic distance analyses reveal that HCV-Ig is the most divergent subtype among the HCV-I confirmed subtypes. Potential genomic recombination events between genotypes or subtype I genomes were ruled out. We demonstrate phylogenetic congruence of previously deposited partial sequences of HCV-Ig with respect to our sequence. Conclusion: In light of this, we propose changing the current status of its subtype-specific designation from provisional to confirmed.