Inheritance of immunity in mice to challenge infection with Nematospiroides dubius

Two lines of mice (Mus musculus) were selectively reared over 10 generations for high (H) and low (L) levels of immune response to Nematospiroides dubius, an enteric nematode parasite. Filial and backcross families were derived from the two parent lines. The mode of inheritance of the trait, immune response to challenge infection with N. dubius, was analysed by comparing the levels of infection in the parental, filial and backcross (BC) families of mice. The immunity of the F1 mice was found to be dissimilar to both parents, but was closer to the H value than to the level of immunity in the L mice. The backcross to H progeny showed levels of immunity approaching that of the H mice, whereas only two of four backcross to L families were low immune responders. Analysis of these results indicated that the inheritance of immunity in these mice to challenge infection with N. dubius was quantitative, partially dominant for high immune response, and additive, in nature.