THE MECHANISM OF VIRAL CARCINOGENESIS BY DNA MAMMALIAN VIRUSES, VI. A NEW CLASS OF VIRUS-SPECIFIC RNA MOLECULES IN CELLS TRANSFORMED BY GROUP C HUMAN ADENOVIRUSES

A new class of virus-specific RNA molecules was found in cells transformed by group C human adenovirus types 2, 5, and 6. RNA isolated from virus-free rat embryo cells transformed by adenovirus 2, 5, and 6 hybridized with all group C adenovirus DNA's (adenovirus 1, 2, 5, and 6) equally well, but not appreciably with group A and B adenovirus DNA's. Most likely no viral genes common to group A, B, and C adenoviruses are transcribed in adenovirus-transformed cells. Group C adenoviruses are closely related since they share 83 to 93 per cent of their base sequences as shown by DNA-DNA homology measurements. Group C DNA's share only 10 to 26 per cent of their base sequences with group A and B DNA's. Moreover, the shared sequences are not transcribed detectably in adenovirus transformed cells. Virus-specific RNA isolated from group C transformed cells contains 49 to 51 per cent G + C, but viral DNA's possess a 7 to 9 per cent higher G + C content. These differences suggest that only a portion of the viral genome with an average G + C content of 49 to 51 per cent is transcribed in group C adenovirus transformed cells.