Abstract
OK10 is a defective leukemia virus which shares some biological and biochemical properties of avian myelocytomatosis virus (MC29). We investigated the pattern of transcription of OK10 in both quail and chicken cells. In both cell types, OK10 produced two polyadenylated RNA species of 8.6 and 3.5 kilobases, which both contained sequences derived from the 5' end of the genome and also the presumed transforming gene (myc). This is a novel form of expression for defective leukemia viruses of the MC29 subgroup and may indicate that there is an as-yet-unidentified protein produced in OK10-infected cells which may be involved in transformation.