Studies of Congenital Transmission of a Leukemia Virus in Mice. ∗

Summary

The pattern of congenital transmission of a leukemia virus was studied in several inbred strains of mice varying in their susceptibilities to virus. Transmission of virus occurred through the maternal line in 3 C3H sublines, 2 low-leukemic and one high-leukemic. RFM mothers failed to transmit infection. There was no indication that parenterally-infected males, of any of the strains studied, transmitted virus to their offspring. Reciprocal foster-nursings of litters born to infected and non-infected mothers revealed that transfer through the mother's milk was the most effective route of transfer. Results of transmission during the prenatal period were equivocal. Leukemic lines were established in C3Hf/Lw and C3Hf/Fg strains through inoculation of virus into prospective parents in the neonatal period. The frequencies and ages at death from lymphocytic leukemia through 4 generations of C3Hf/Gs mice revealed no loss of virulence of virus. Apparently, low-leukemic and high-leukemic lines may be established simply through foster-nursing of litters. There was no evidence to support the concept for transmission of virus through germinal cells. The results reported here concerning the pattern for congenital transmission of Moloney virus stand in sharp contrast to the patterns for transfer of potentialities to develop leukemia in the high-leukemic strains of mice, AKR, C58, F and C3Hf/Fg.