The inability of a diabetogenic virus to induce diabetes mellitus in athymic (nude) mice.

The effect of a known diabetogenic M-strain encephalomyocarditis(EMC)-virus in athymic nude mice (lacking the thymus-dependent lymphocyte system), and in heterozygous littermates and homozygous normal mice of the background strain (C57/B16) was investigated. While by 3 weeks 4 out of 4 surviving virus-inoculated littermates and 9 out of 9 inoculated normal mice developed diabetes mellitus, none of the 7 surviving virus-inoculated nude mice became diabetic. Virus was isolated from all inoculated animals, including non-diabetic nude mice. It is concluded that it is the response of the thymus-dependent lymphocyte system evoked by the virus rather than the virus itself that leads to damage to the insulin producing cell.