Detection of the Hepatitis C Virus

     Because the clinical characteristics are the same for all types of acute viral hepatitis, laboratory testing is needed to identify the specific viral cause of illness. Confirmation of acute hepatitis C results when a negative test result occurs for Hepatitis A Virus and Hepatitis B Virus with one of the following: Antibody to hepatitis C virus (anti-HCV) screening-test-positive with a signal to cut-off ratio predictive of a true positive by CDC guidelines, Hepatitis C virus recombinant immunoblot assay (HCV RIBA) positive, or nucleic acid test (NAT) for HCV RNA positive. The two main classes of assays used in the diagnosis and management of HCV infection: serologic assays that detect specific antibody to hepatitis C virus (anti-HCV) and molecular assays that detect viral nucleic acid. The development of molecular assays for blood borne viral infections has made it possible to detect acute infections at an earlier stage than would be possible with conventional techniques and to measure the concentration of virus present in blood during the acute or chronic phases of infection. Molecular methods proved most useful for the identification of viruses that are either completely unable to be cultivated or can be cultivated only with great difficulty.  Several commercial assays for HCV genotyping are also available for use in clinical laboratories. Detection of HCV genotype is the most significant predictor of response to anti-HCV therapy and is used to predict treatment response and guide duration of therapy. The importance of nucleic acid testing over antibody testing can be seen in the blood banking industry. It is estimated that 9.7 Hepatitis C virus infected units per million donations go undetected by Antibody assays. With the use of nucleic acid test this risk is reduced to 2.72 infectious units per million donations. Nucleic acid testing reduces the detection window by an average of 25.8 days over antibody testing. Hepatitis C virus nucleic acid testing clearly increases the detection rate of HCV in donations that are immunosilent and help prevent these specimens from entering the blood supply. There are currently multiple nucleic acid assays available that use different methodology for the detection of the HCV nucleic acid RNA. For a full listing of the currently availible FDA approved testing methods for HCV refer to the following link. FDA approved