Use and interpretation of hepatitis C virus diagnostic assays.

The HCV genotype, HCV RNA, HCV core antigen, and anti-HCV antibodies are the four biologic markers currently used in hepatitis C. Acute and chronic hepatitis C are diagnosed by anti-HCVantibody (enzyme immunoassay) and HCV RNA detection with sensitive molecular biology techniques. Other virologic tools include HCV genotype determination and HCV RNA quantification; these are used to guide the individual treatment choice, and also to monitor treatment efficacy. Overall, the management of HCV infection has been vastly improved by the use of virologic assays. These assays remain to be fully standardized and automated, however, and more clinically relevant cut-off values are required on which to base management recommendations. More sensitive and accurate HCV RNA assays will improve not only the assessment of the response to antiviral treatment, but also our understanding of antiviral resistance. These improvements, and the development of new antiviral drugs (see the article by Drs. DeFrancesco and Rice elsewhere in this issue), should help to optimize the treatment of HCV infection.