Sequential changes in small intestinal structure and function during rotavirus infection in neonatal rats.

Rotavirus infection is the most common cause of acute diarrhoea in children worldwide. The structural and functional consequences of mammalian rotavirus infection in the small intestine have been incompletely studied and the mechanism of enterocyte damage poorly defined. This study used a neonatal rat model of group B rotavirus infection to study the natural history, clinical features, and the structural and functional consequences of infection in the small intestine. Group B rotavirus infection in eight day old neonatal rats produced diarrhoea by 24-36 hours, which was accompanied by weight loss during the early stages of infection. By seven days the diarrhoea had ceased and body weight was similar to noninfected controls. Rotavirus could be recovered in faeces from 24-72 hours. Light microscopy and morphometry confirmed reduction in villous height in both jejunum and ileum, with a reduction in total mucosal thickness indicating true flat mucosa. Increase in crypt depth followed villous shortening and continued as villous height progressively increased between 96-168 hours. Steady state perfusion of the entire small intestine with a plasma electrolyte solution confirmed the presence of a net secretory state for water between 12-48 hours, with a parallel reduction in sodium absorption. Group B rotavirus infection produces a self limiting acute diarrhoeal illness in neonatal rats similar to human rotavirus infection. Infection causes a reversible flat mucosa resulting from enterocyte loss associated with a net secretory state for water and impaired sodium absorption as a functional correlate. These findings may have relevance for the pathogenesis of human rotavirus infection.