A2G mice could be solidly immunized against the Ehrlich ascites tumor by single intraperitoneal injections of homogenized and lyophilized tumor cells which had been infected with oncolytic strains of influenza A virus. Similar homogenates from noninfected tumor cells were not immunogenic, even when mixed with egg-grown virus.

The immunizing principle in viral oncolysates could not be separated from the oncolytic virus by differential centrifugation or adsorption to and elution from red cells. It could be inhibited by antibody raised in rabbits against the egg-grown oncolytic virus. This reaction showed serologic specificity. Thus, the immunogenicity of an oncolysate produced with the WSA strain of neurotropic influenza virus could be inhibited by rabbit anti-WSA, but not by rabbit antibody to the TUR strain of fowl plague virus. Conversely, the immunogenicity of an oncolysate prepared with the TUR strain could be inhibited by rabbit anti-TUR, but not by anti-WSA.

When mice were preimmunized (primed) with egg-grown WSA virus, their antitumor response to a later injection of WSA oncolysate was of the anamnestic type. Priming with egg-grown influenza B virus had no such effect.

It was concluded that the immunogenicity of certain host cell components was greatly increased by incorporation into the makeup of the oncolytic virus.

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