Changes in transcription of endogenous type-C virus genome during mouse liver regeneration

In the present study the extent of endogenous, type-C virus genome transcription in normal and regenerating mouse liver was analysed by using the technique of nucleic acid hybridization. The RNA preparations from regenerating liver tissues collected at various intervals following partial hepatectomy, and from normal liver samples of BALB/c mice, were hybridized to 3H-DNA complementary to 60 to 70S RNA of an endogenous, N-tropic virus, released spontaneously from BALB/c mouse cells in culture. Although partial transcription of the endogenous virus genome can be clearly detected in normal liver, a significant increase in the level of virus-specific RNA synthesis in the regenerating liver, in comparison to normal liver, is apparent, following partial hepatectomy. This increase in virus-specific RNA synthesis attains its highest level just before the level of DNA synthesis in the regenerating liver reaches its maximum. These observations may indicate a qualitative or quantitative change in the endogenous type-C virus genome transcription pattern in hepatocytes, in response to partial hepatectomy and suggest that this change in the transcription pattern and the initiation of cell proliferation, in regenerating livers, are probably sequential and related events.