HCV’s considerable genetic variability, which exists at various levels across viral populations in individual infected individuals at any given moment and during evolution, is a distinguishing feature of the virus. Because of this, it was discovered in 1993 through phylogenetic analysis of incomplete HCV sequences from several patient isolates worldwide that the virus could be divided into six major genotypes with significant subtypes. Based on a study of full-length ORF sequences, this categorisation was later verified. A seventh significant genotype has been identified, albeit only detected in a few people. An eight genotype has also been recently identified. The number of published ORF sequenced HCV isolates has dramatically increased because of breakthroughs in sequence analysis tools. This chapter seeks to identify the 7 main genotypes and 93 additional subtypes of HCV.
Part of the book: Hepatitis C