Murine teratocarcinoma: A model for virus-cell interaction in a differentiating cell system

The stem cell of the murine teratocarcinoma is refractory to infection with Simian virus 40 and polyoma. Utilizing various procedures, we attempted to alter this block to infection by modifying the infection procedure. Multiple infections with high‐titer SV40 and pretreatment of cells with DEAE‐dextran or the carcinogen 4‐nitroquinoline l‐oxide did not induce embryonal carcinoma cells to produce T‐ antigen. Co‐infection with adenovirus 5, which infects the embryonal carcinoma, and SV40 did not induce the expression of SV40 Tantigen. Therefore, these procedures did not overcome the block to virus infection. The assay for the SV40 T antigen was immunofluorescence; however, the immunoprecipitation technique did not detect T antigen in the infected embryonal carcinoma cells. Finally, the viral DNA present in the embryonal carcinoma was examined for its ability to replicate. These studies showed that viral DNA was not replicating as assayed by the viral DNA's sensitivity to UV irradiation when replicating in the presence of 5‐bromodeoxyundine.