About the influence of halogenated pyrimidines on the in vivo-oncogenesis

Reported are in vivo trials on Friend virus-leukemia (FVL), on methylcholanthren-induced fibrosarcomas of the mouse, and on amelanotic melanoma No. 3 of the Syrian hamster after treatment with halogenated pyrimidines, 5'-bromodeoxyuridine (BUDR) and 5'-iododeoxyuridine (IUDR) as to provoke genuine oncorna viruses. Till now, no prove exists that in tissue culture propagated C-type particles are really oncogenic. From the results demonstrated here the conclusion can be drawn that the chosen in vivo-conditions neither oncogens, possibly located in the cells, will be finished to complete oncogenic viruses, nor a spread and multiplication of dormant viruses will take place due to a provocation treatment of the hosts with halogenated pyrimidines. It seems, therefore, that the requirements to activate oncogens in vitro are absolutely different to those needed under in vivo conditions.