Scanning electron microscopy of intestine of gnotobiotic piglets infected with porcine rotavirus.

The development of intestinal lesions caused by the porcine rotavirus were studied in six day old gnotobiotic piglets by scanning electron microscopy. The onset of diarrhea followed an incubation period of 17 to 31 hr. The first detectable lesion was observed in the ileum at 12 hr postinfection, a few hours before the onset of diarrhea. At this time enterocytes appeared swollen and began to separate from each other. Seventeen hours after the onset of diarrhea, lesions were quite severe jejunum and ileum. Enterocytes were detaching from the lamina propria leaving denuded areas. Microvilli were sparse on the cell surfaces and there was marked villous atrophy. Regeneration of ileal mucosa was evident at 4.8 days after the onset of diarrhea. Nine days after recovery from diarrhea the intestinal villi had returned to near its normal structure but there remained some evidence of mucosal damage.