HCV - The molecular genetics of hepatitis C viral infection HCV molecular biology: HCV is a positive-stranded RNA Flaviviridae virus with a 9.6kB genome. The genome encodes a polyprotein of approximately 3000 amino acids which is subsequently cleaved by host and virus-specific proteases to yield 4 structural and 6 nonstructural polypeptides. The 4 functional proteins include a metalloproteinase (NS5A), serine protease (NS3/NS4A), RNA helicase (NS3), and a RNA-dependent RNA polymerase (NS5B). Six different genotypes of HCV have been described, with genotype 1 being the most prevalent worldwide and genotype 4 being the most prevalent in the Middle East.