Detection of the hepatitis C virus by rt-PCR.

The hepatitis C virus (HCV) is an orgainsm of the age of molecular biology, for its discovery and much of the research into the infection have relied heavily on molecular techniques. The development of molecular cloning enabled a successful strategy that finally identified HCV (1)as the cause of 90% of posttransfusion (2)and > 50% of sporadic non-A, non-B hepatitis (3) after the failure by immunological techniques to discover the responsible agent. It is an important infection as most infected patients developed chronic hepatitis (> 50%) that can progress to cirrhosis and hepatocellular carcinoma (4-6) . Following the identification of the viral genome, antibody tests were developed which could detect exposure to the virus (7). The presence of antibodies to HCV, however, does not distinguish between those with chronic infection and those who had cleared the virus. Chronic HCV infection can be difficult to diagnose as patients may be asymptomatic and have normal liver biochemistry (8),(9) despite abnormal liver histology. Therefore, demonstration of virus RNA (usually from serum samples) is often necessary to confirm Infection. Detection of HCV RNA requires the sensitivity of nucleic acid amplification (e.g., the polymerase chain reaction) as circulating levels of vnus RNA can be very low (10),(11). Such tests are now widely used to confirm infection, monitor the response to anti-viral therapy, and in epidemiological studies of HCV infection.