Mouse intestinal villi as a model system for studies of rotavirus infection.

Rotavirus replicates in the mature enterocytes lining the villi of the small intestine and the availability of an in vitro system for culturing these natural target cells would contribute to substantial advances in the understanding of the pathogenesis of rotavirus. A novel in vitro system was established for culturing isolated small intestinal villi from suckling mice, and the susceptibility of the villus cells to the wild-type murine rotavirus EDIM-Cambridge (ECwt) infection was assessed by immunocytochemistry staining and ELISA. Cell viability of cultured villi infected by rotavirus was estimated to be higher than 70% 16 h post-infection, whereas the accumulated rotavirus structural and non-structural antigen was found to reach a maximum value at 24 h post-infection. Terminal apoptosis was found in about 65% of villus cells 22 h post-infection as detected with either propidium iodide or Hoechst 33342 staining. Mock-infected villus cells exhibited a slight tendency toward more extensive chromatin fragmentation compared to their rotavirus-infected counterpart, mainly when caspase-3 activity was measured. Examination of villus cells by ELISA indicated that the amount of rotavirus structural antigen accumulated at 12 h post-infection was nearly the same regardless of the intestinal section (duodenum, jejunum and ileum) used. The isolation, culture and infection of small intestinal villi from suckling mice has led to the introduction of a useful model for rotavirus studies.