Abstract
Gross, immunofluorescent, and light microscopic findings in seven gnotobiotic calves inoculated orally with a Reo-like neonatal calf diarrhea virus were compared to findings in three control gnotobiotic calves. Neonatal calf diarrhea virus infected primarily the villous epithelium of the small intestine. Calves examined within 1.5 h after onset of diarrhea had tall columnar immunofluorescent villous epithelial cells in the middle and lower small intestine. Calves examined 2–4.5 h after onset of diarrhea had cuboidal to squamous villous epithelial cells and an increase in reticulum-like cells in the villous lamina propria of the middle and lower small intestine. Viral tilers were 106 and 108 in colonic contents from two calves inoculated with cell-culture-adapted virus and necropsied, respectively, 2 and 6 h after onset of diarrhea.