In Vitro Transformation by an Avian Adenovirus (CELO). I. Hamster-Embryo Fibroblastic Cultures

Chicken-embryo-lethal-orphan (CELO) virus was shown to transform hamster-embryo fibroblastic cells in vitro. The first signs of infection were at 24 hours when pyramidal or stellate cell forms were observed in a disorganized growth pattern. After 4 passages fibroblastic elements gave way to epithelioid-like cells. Virus production decreased as the number of transformed cells increased. A virus-specific intranuclear “T” antigen was observed in most cells by immunofluorescent techniques. Cells from the seventh and twelfth passages induced fibrosarcomas when inoculated subcutaneously into hamsters 3–4 weeks old.