Detection of a 5' UTR variation in the HCV genome after a long-term in vitro infection

The TOFE lymphoid cell line from normal human bone marrow is susceptible to infection by a hepatitis C virus (HCV) serum strain. A sequence analysis of the 5' untranslated region (UTR) of HCV before and after long-term in vitro infection revealed one base substitution at position -158 (C > T) of the 5' UTR. We performed the direct sequencing of 5' UTR polymerase chain reaction-amplified sequences of the HCV genome: a) from the original serum-derived strain; b) from TOFE cell extracts 6 months post infection. This base substitution in the regulatory elements of the 5' UTR might be related to the ability of the virus to grow in cell culture.