Regulation of Leishmania populations within the host. V. Resistance to L.donovani in wild mice.

Samples of wild Mus musculus from two populations in areas endemic for leishmaniasis and from seven populations in non-endemic areas were found to be uniformly resistant when tested for their early response to Leishmania donovani infection. Males from one endemic and one non-endemic population were crossed to females from two inbred strains of mice carrying the susceptible allele for the innate resistance gene, Lsh, on different genetic backgrounds. Bimodality of liver parasite counts and a close fit to Mendelian ratios obtained in F2 and backcross mice indicate that the uniform resistance observed in wild mice is most probably due to mono-morphism for the resistant allele at the Lsh locus. The relevance of these findings to the potential capacity of Mus musculus to act as a reservoir for visceral leishmaniasis for for other intracellular pathogens thought to be under the control of the same gene is discussed.