Bioactivity of male (sperm transmitted) mouse mammary tumor virus as influenced by donor, recipient and age at treatment.

The sperm collected from mammary tumor virus (MTV)-carrying mice (C3H, BALB/cfC3H, BALB/cfRIII and RIII) was separately tested for mammary tumor-inducing activity in (BALB/c x C3Hf)F1, (BALB/c x RIIIf) F1, and BALB/c female recipients by i.p., injection of 0.1 ml of the sperm at 1-2 weeks or at 3 months of age. A total of 551 recipents was observed, including control mice. The results may be summarized as follow: 1) mammary tumor incidence in experiments with or without histocompatibility between sperm donor and recipient is the same; 2) bioactivity is related to the type of MTV (C3H, RIII) and to the type of recipient, not to the sperm donor; 3) the activity of RIII MTV released in the sperm appears to be less influenced by the age of recipients than is that of C3H MTV; 4) BALB/c recipients are more susceptible to C3H than to RIII sperm-released MTV; 5) (BALB/c x RIIIf) F1 hybrids are resistant to sperm-released MTV, especially to C3H MTV infection, and show a 34% incidence of late spontneous lymphomas inherited by the RIIf male parent; 6) (BALB/c x C3Hf) F1 hybrids are susceptible to both C3H and RIII sperm-released MTV and show a 30% incidence of late spontaneous mammary tumors due to genetic transmission of MTV by the C3H male parent.