“Induction” of Viral Antigen in Established Cell Line (SP-8) Derived from Shope Virus-induced Cutaneous Papilloma of Rabbits ∗

Summary

In the SP-8 cells established from Shope papilloma virus-induced cutaneous tumors of domestic rabbits, intranuclear synthesis of the SPV antigen was clearly demonstrated by immunofluorescent technique up to fourth transfer generation. Since then, such demonstrable viral antigen disappeared completely from the cells. When the cultures of the SP-8 cells were transferred from the ordinary temperature of 37-30°, the SPV antigen reappeared in the cells after about a week of incubation and appeared in approximately 80% of the cells in the culture after 13 days. The immunofluorescence was exclusively seen in the cytoplasm. Further-more, the cellular extract prepared from the SP-8 cells cultures at the lowered temperature exhibited capacity to infect CRK cells as determined by the immunofluorescent technique. These findings were interpreted as an evidence supporting the view that the SPV genome, possibly a complete set of it, is persisting in these SP-8 cells.