Analysis of avian myeloblastosis viral RNA and in vitro synthesis of proviral DNA.

Two virus-specific RNA species of 7.5 and 7.0 kilobases have been identified in avian myeloblastosis virus (AMV) by denaturing gel electrophoresis and blot hybridization analysis, and they were found to be in a 10:1 ratio. The individual RNAs direccted the cell-free synthesis of the 76,000-dalton "gag" protein and the 180,000-dalton "gal-pol" protein, thereby demonstrating 5' sequence homology of approximately 4.9 kilobases between the two species. Synthesis of these two precursor proteins by the AMV genome indicates structural differences between AMV and other avian acute leukemia viruses. The two viral RNAs were transcribed into complete cDNA copies with AMV DNA polymerase. Linear proviruses were found to be 90--100% resistant to S1 nuclease. Analysis of single-stranded transcripts demonstrated two distinct species of 2.6 and 2.3 x 10(6) daltons, and analysis of duplexes formed from the single-stranded transcripts demonstrated species of 5.2 and 4.0 x 10(6) daltons.