Interaction of Vaccinia Virus with the Ehrlich Ascites Carcinoma.

The IHD-T strain of vaccinia virus exhibited an oncolytic effect upon Ehrlich ascites tumor cells proliferating in the peritoneal cavity of the mouse. Either premature death or a prolonged survival time of tumor-bearing mice might result depending on whether the virus was inoculated into an established tumor (5 days) or whether it was inoculated simultaneously with, or 2 days after, the tumor cells. In the latter case, the 50 per cent survival time in days, ST50, was increased fourfold or greater, whereas in the former the mice died several days before the controls. In a virus-immune host multiplication of the virus in the tumor cells was suppressed, and the oncolytic effects of the virus were abolished.