Prevention of 334C murine virus-induced leukemia by transmission of maternal immunity to offspring
Mice were protected against development of virusinduced leukemia late in life when they were suckled on female mice immunized as adults with 334C murine leu kemia virus, a member of the Friend-Moloney-Rauscher subgroup of murine leukemia viruses. Young adult, ran dom-bred Ha/ICR Swiss females were immunized with one to three injections of virus filtrate from organs of leukemic mice at weekly intervals and were mated during or after immunization. Offspring were challenged at birth by injec tion
... irth by injec tion with 334C virus and then suckled on immunized females until weaned. The incidence of leukemia was reduced to an average of 10% in offspring from immunized females, compared to an average of 72% in offspring from nonimmunized females. The capability of virus-immunized females to protect their young extended over a period of 5 to 6 months. Neonatal mice also were protected against development of leukemia when they were suckled on virus-immunized females either before or after infection by vertically trans mitted 334C virus in reciprocal foster nursing experiments. Offspring were suckled on virus-immunized mothers for 2, 8, and 14 days before being transferred to virus-infected females. Leukemia developed in 36, 15, and 14% of offspring, as compared with 71, 38, and 7% in control litters (offspring from nonimmunized mothers suckled on virusinfected females). When offspring were suckled on virusinfected mothers for 2, 8, and 14 days before being transferred for suckling to virus-immunized females, leu kemia developed in 6, 33, and 81% as compared with 83, 68, and 72% in control litters (virus-infected offspring suckled on normal females). The results of these experiments define a critical period, early in life, during which the course of virus infection can be altered and the incidence of leukemia in adult life greatly influenced. Thus, this murine system provides a model for exploration of the application of combined immunotherapy and antiviral chemotherapy to the prevention of virusinduced leukemia.