Coxsackievirus infection of mice. I. Viral kinetics and histopathological changes in mice experimentally infected with coxsackieviruses B3 and B4 by oral route.

We followed the viral kinetics and histopathological changes in different organs of immunocompetent mice infected orally with coxsackieviruses B3 (CVB3) Nancy strain and B4 (CVB4) JVB strain separately. The viruses used were not adapted to mouse organs. In the acute phase of infection, the viral kinetics indicated virus replication in the heart, spleen, thymus, pancreas, and small and large intestines. This was accompanied by histopathological changes, mild infiltration of mononuclear cells and fibrosis in the heart. The necrotic changes with mononuclear infiltration and fibrosis in the myocard was observed on days 56 and 71 p.i. in the CVB4-infected animals only. In the mice infected with CVB3 and CVB4 a prolonged presence of infectious virus was shown in the spleen and small intestine; in the latter viral antigen was localized in smooth muscles of the muscular wall immunohistochemically. This is the first report on prolonged replication of coxsackieviruses (CV) in the spleen and small intestine in orally infected mice.