The RNA of Avian Acute Leukemia Virus MC29

The RNA of myelocytoma virus MC29, a replication-defective avian acute leukemia virus, was investigated. Sedimentation and electrophoretic analyses indicated that the virus contains a distinct 28S RNA with about 5700 nucleotides. It is the smallest avian tumor virus RNA detected to date. The small size of the RNA suggests that the defectiveness of the virus is due to deletions in replicative genes. The RNA shared 3 to 5 of 30 large RNase T1-resistant oligonucleotides with the RNA of other avian leukosis and sarcoma viruses. Hybridization indicated that 61% of the viral RNA contains sequences in common with other avian sarcoma and leukosis viruses. At least 32% of the RNA (about 1800 nucleotides) appear to be MC29-specific and may represent the transforming information of the virus. Sequences of the conserved transforming gene of avian sarcoma viruses were not detected in MC29 RNA. It was concluded that the transforming sequences of MC29 RNA define a new class of avian tumor viral transforming genes.