In Vitro Neoplastic Transformation of Hamster Embryonic Skin and Subcutaneous Tissue Cells with Small-Plaque and Large-Plaque Variants of an Avian Adenovirus (Chicken Embryo Lethal Orphan)1

When hamster embryonic skin and s.c. tissue cells were infected in vitro with small-plaque (SP) and large-plaque (LP) variants of chicken embryo lethal orphan virus, neoplastic cell lines were established. The SP cell line was made up of pleomorphic cells, whereas the LP cell line consisted of cells that were spindled to oval. The SP but not the LP cell line revealed virus-specific, intranuclear T antigen by the indirect immunofluorescent technique. Virus isolations were possible during the early passage levels in both of the cell lines. The SPand LP-transformed cell lines induced tumors in weanling hamsters; however, the SP cells induced tumors at an earlier time in passage. Histologically, the SP tumors resembled anaplastic sarcomas, whereas the LP tumors were spindle-celled sarcomas. The role of the viruses in the neoplastic transformations is discussed.