Encephalomyocarditis virus induced diabetes mellitus in mice: long-term changes in the structure and function of islets of Langerhans.

Adult male mice infected with the M variant of encephalomyocarditis virus develop hyperglycaemia acutely as a consequence of B cell injury. The severity of the metabolic disease is variable and many animals become normoglycaemic during convalescence. The islets of Langerhans of these mice exhibit minor structural changes, but there are no significant abnormalities of insulin and glucagon secretion. In contrast, animals with persistent hyperglycaemia exhibit striking morphological alterations in the islets. The A cell mass is prominent, whereas B cells are reduced in number and exhibit striking cytological features. These changes are associated with both hypoinsulinaemia and hyperglucagonaemia.