Brief Communication: Comparison of Three Mammary Tumor Viruses in Genet- ically Similar Susceptible Mice l

SUMMARY-Three naturally occurring milk-borne mammary tumor viruses (MTV) from inbred mouse strains C3H, A, and DD (with their characteristic mammary tumor in-cidences) were compared in genetically similar susceptible BALBjc female breeders and virgins. The 3 MTV's differed as to their on-cogenic ability in relation to mammary tumors in the virgins. C3H-MTV was more effective than either A- or DD-MTV, and DD-MTV was the least oncogenic. The MTV from strain A was more like C3H-MTV than DD-MTV.-J Nat