This virus was genetically modified, but it sounds like a simple change -- dropping a viral adaptation that, while necessary to remain viable against normal cells, otherwise curtails the virus's replication. Could such a modification be part of the normal viral mutation churn in nature, meaning there are naturally occurring anti-cancer saluviruses from time to time? And might that also be the scientific explanation for occasional "miraculous" remissions from cancer?

Should we be searching for such novel agents inside cancer survivors?