Detection and analysis of replicating hepatitis C virus RNA in hepatocellular carcinoma tissues

Although persistent hepatitis C virus infection is closely associated with the development of hepatocellular carcinoma, the nature of hepatitis C virus replication in the hepatocellular carcinoma tissue has not been fully characterized. To study this, carcinoma and non-carcinoma tissues were obtained from five patients with hepatocellular carcinoma. Total RNA was recovered from each tissue, and a portion of the envelope gene of replicating hepatitis C virus was amplified by minus-strand-specific reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by single strand conformation polymorphism analysis and sequencing. Hepatitis C virus replication was detected in both carcinoma and non-carcinoma tissues in four patients who were positive for serum hepatitis C virus markers. In one patient, a single species with identical envelope 2 genome was obtained from both carcinoma and non-carcinoma tissues. In the other three patients, the replicating hepatitis C virus existed as a mixture of 2–5 species with different but highly homologous (82–99%) envelope 2 genomes (quasispecies populations). The constitution of viral populations was different between carcinoma and non-carcinoma tissues. A total of ten sequences were recovered; four sequences were found in both tissues, two were found in carcinoma tissues, and four were found in non-carcinoma tissues. The differnce in the constitution of quasispecies populations between carcinoma and non-carcinoma tissues confirms the unequivocal replication of hepatitis C virus in both tissues, and may imply the presence of different biological properties among hepatitis C virus with different sequences.