Oncogenes of Avian Acute Leukemia Viruses are Subsets of Normal Cellular Genes

Avian acute leukemia viruses are a group of defective retroviruses which cause neoplasia in animals after short periods of latency. Transformation induced by the acute leukemia viruses usually manifest the direct expression of one or two viral onc genes that include characteristic elements transduced from cellular genes termed proto-oncogenes. Table 1 demonstrates the oncogenic properties of these viruses. Of particular interest to our laboratory is the MC29 subgroup of acute transforming viruses with onc-specific sequence termed myc as well as the avian myeloblastosis virus (AMV) subgroup with an onc-specific sequence termed myb. There are dramatic biologic differences between these two subgroups of viruses. As illustrated in Table 1, the MC29 subgroup possesses a broad spectrum of oncogenicity in vivo, causing leukemia and solid tumors in animals, and the ability to transform a variety of cells such as fibroblasts and hematopoietic cells in vitro. By contrast, the AMV subgroup has a much narrower spectrum of oncogenicity in vivo, causing leukemia, but not solid tumors, and possesses the ability to transform only hematopoietic cells in vitro.