In vitro synthesis and characterisation of full- and half-genome length complementary DNA from avian oncoviruses

Abstract

RNA TUMOUR viruses carry an RNA-dependent DNA polymerase which can transcribe the viral RNA genome into single-stranded and double-stranded DNA in detergent-disrupted virions1,2. For several years since the discovery of this enzyme, only short DNA fragments of about 100–200 nucleotides long could be produced3. Recently, conditions have been described for the synthesis of possibly full-genome length complementary DNA (cDNA)4–6. The in vitro conditions described, however, were not well characterised and did not seem to be very efficient. We report here an efficient synthesis in vitro of half- and possibly full-genome length cDNA in avian oncoviruses. These two discrete species of cDNA were synthesised in large quantities. Furthermore, some of the half-genome length cDNA were found to form single-stranded circular molecules with a distinct secondary structure.