Action of riley's enzyme-elevating virus on tumour-bearing mice.

RILEY virus (RV) is a passenger agent occurring in most mouse tumours which are subjected to repeated transplanting passages1–6. The influence of this virus on tumour-bearing hosts has not yet been clarified, though its stimulating and accelerating effects on tumour-growth have been discussed3,5. There is a significant elevation of LDH-values after virus-infection of tumour-bearing mice as compared with tumour-free hosts1,3,5 (termed ‘tumour-virus synergism’ by Riley5). This phenomenon is of special interest, because the natural occurrence of RV is almost restricted to tumour-bearing mice. Enhanced values of plasma-LDH in tumour hosts7 might be induced mainly by RV. We have investigated the effects of RV on three different tumours of mice previously free of the agent.