Hepatitis C Virus

What it is…

HCV is a small (50 nm in diameter), enveloped, single-stranded RNA virus of the family Flaviviridae. The genome of the virus mutates rapidly, and the resultant changes in the envelope protein may explain how it escapes clearance by the immune system. There are at least 6 major genotypes and more than 30 subtypes of HCV. The different genotypes have different geographic distributions. Genotypes 1a and 1b are the most common in the United States.

Genotypes 2 and 3 are present in only 10 to 20 percent of patients. Overall there is little difference in the severity of disease or outcome of patients infected with different genotypes. However, patients with genotypes 2 and 3 are more likely to respond to alpha interferon treatment.