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We tested serial serum samples for hepatitis C virus RNA from patients undergoing treatment for chronic hepatitis C with interferon-alpha using an assay that combined reverse transcription and polymerase chain reaction. The subjects studied were 20 patients with chronic hepatitis who had serum antibody to hepatitis C virus (anti-C100-3). Before therapy, hepatitis C virus RNA was detected in 18 (90%) and 20 (100%) patients using primer sets derived from the NS3 region or the 5'-noncoding region of hepatitis C virus, respectively. Hepatitis C virus RNA became undetectable in all patients whose ALT level fell into the normal range during therapy. However, hepatitis C virus RNA reappeared in all patients whose ALT levels rose again after therapy, usually before the relapse. In patients whose ALT levels did not become normal, hepatitis C virus RNA did not disappear during therapy. Thus therapy with interferon-alpha appears to be beneficial in chronic hepatitis C because of its suppressive effects on hepatitis C virus replication. Detection of hepatitis C virus RNA in serum is useful for evaluating the antiviral effect of interferon.

We describe a method for quantifying hepatitis C virus RNA in serum. This competitive assay combines reverse transcription and polymerase chain reaction and is based on coamplification of the target RNA with known amounts of synthetic mutated RNA. We tested serum samples from 104 hepatitis C virus carriers (9 asymptomatic blood donors and 95 patients with type C chronic liver disease) to determine the relationship between the replicative level of hepatitis C virus and various stages of the carrier states. The amount of circulating hepatitis C virus RNA ranged from 10(4) to 10(9.5) genomes/ml serum. The titer of hepatitis C virus RNA (logarithmic transformed copy numbers of RNA per milliliter of serum) was lower in asymptomatic blood donors (5.4 +/- 2.0) and in patients with chronic persistent hepatitis (7.3 +/- 1.1) than in patients with chronic active hepatitis (7.9 +/- 0.8), cirrhosis (7.8 +/- 0.7) or hepatocellular carcinoma (7.9 +/- 0.7). The titer of hepatitis C virus RNA was significantly lower in carriers younger than 40 yr old and correlated positively with the logarithmic transformed serum ALT level. Logistic regression showed that age and titer of hepatitis C virus RNA correlated independently with the stages of liver disease. These results showed that the replicative level of hepatitis C virus is higher in advanced liver disease and that elevation of viral replication may play an important role in liver injury and progression of liver disease. This competitive assay is useful in evaluating the state of viral replication in hepatitis C virus infection.