Antagonistic Action of Certain Neurotropic Viruses Toward a Lymphoid Tumor in Chickens with Resulting Immunity. ∗

Conclusions

1. RPL-12, a transplantable lymphoid tumor of chickens, can be caused to regress, without any apparent damage to the host, by superimposed inoculations of Russian Spring-Summer, West Nile, Japanese B encephalitis, St. Louis encephalitis or louping-ill viruses.

2. Chickens which have been inoculated with the RPL-12 tumor followed by a superimposed infection with any of the 5 viral agents are rendered immune, as a rule, to challenge by homologous tumor even though the original inoculation with tumor may not have produced a palpable tumor.

3. The infective titer of RSS virus in infected tumor tissue is equal to that of infected mouse brain.

4. RSS virus obtained from infected mouse brain has a high oncolytic action when introduced into the tumor area but is less effective when it is introduced at a distance from the tumor.

5. RSS virus obtained from infected RPL-12 tumor has a high oncolytic action when introduced either in the tumor area or at a distance from the tumor.