Expression of integrated hepatitis B virus DNA in PLC/PRF/5, Hep 3B, and L6EC3 cell lines detected by in situ hybridisation.

The expression of the DNA of hepatitis B virus (HBV) was analysed in three cell lines (PLC/PRF/5, Hep 3B, L6EC3) which contain the HBV DNA integrated in their genome and release the viral surface antigen (HBsAg) in relation to cell growth. Using the in situ hybridisation technique and a cloned DNA probe specific for hepatitis B virus (PTKH9), the intracellular viral RNA localisation showed that for the three cell lines, HBV RNA are present in the different cell compartments according to the age of the culture. The nucleolar and nuclear localisation are visible in the early stages of the cell growth, whereas in the later stages viral RNA are found in the cytoplasm corresponding to the maximal production of the HBsAg. These observations suggest that the nucleolus is implicated in the expression of the integrated form of HBV genetic information, the regulation of which is linked to cell growth.