Tumor Immunity following Viral Oncolysis

Abstract

We have already mentioned that the most readily reproducible survival rates after viral oncolysis were obtained when use was made of mice genetically resistant to the oncolytic virus. What should now be done with mice which have survived oncolysis? Probably one of the most natural things to do would be to test such survivors for their susceptibility to re-implantation of the same tumor. Such challenge experiments were reported by Koprowski et al. (1957). These workers found that PRI mice which had survived oncolysis of a nonspecific tumor by West Nile virus were highly resistant to challenge with the same tumor and several other transplantable tumors. The mechanism of this resistance was not studied, but the experiments gave rise to an interesting speculation known as the “cancer cure 1957”. Since a very-strong immunity to several tumors was induced by oncolysis of one transplantable tumor, it was thought that such an immunity could perhaps influence even a spontaneous tumor. Take a mouse with a spontaneous tumor. Inoculate it with a transplantable tumor. Induce viral oncolysis within this transplanted tumor with an appropriate oncolytic virus. The transplanted tumor will be destroyed and immunity to this tumor will develop. If now this immunity is also directed against the spontaneous tumor, the growth of the latter should be checked. Unfortunately, for this experiment to work, a spontaneous tumor should arise in a strain genetically resistant to the oncolytic virus to be used. The PRI strain was not suited to this type of experiment, because it failed to develop spontaneous tumors. It was failed to deverlop spontaneous tumors.