Response of C3H-AvyfB female mice to a low oncogenic, milk-borne mammary tumor virus.

When low oncogenic milk-borne mammary tumor virus (MTV) of strain DD was tested in C3H-AvyfB mice, as compared with the similar strain C3HfB, mammary tumors occurred with a higher incidence and at lower age in C3H-AvyfBfDD (with DD-MTV) than in C3HfBfDD (with DD-MTV), as observed in virgin females. Since the effect of breeding tended to mask any difference between the breeders, mammary tumor incidences were similar with a slightly higher age at tumor occurrence in the C3H-AvyfBfDD females. Thus the C3H-AvyfB virgins (with the Avy gene) were almost as susceptible to mammary tumors with the less potent DD-MTV as were C3HfB virgins with the more virulent C3H-MTV of strain C3H.