Experimental transmission of abnormal prion protein (PrPsc) in the small intestinal epithelial cells of neonatal mice

Using an immunohistochemical method, we attempted to detect the transmission of abnormal prion protein (PrPsc) to the enterocytes of the small intestine of neonatal mice by oral exposure with sheep brain affected by scrapie. Five 1-day-old neonatal mice were exposed by oral inoculation to the homogenized brain of a scrapie-affected sheep. In the small intestine of all mice 1 hour after inoculation, immunoreactivity with antinormal prion protein (PrPc) antibody was seen in the cytoplasm of villus enterocytes. This finding suggests transmission of abnormal PrPsc into the cytoplasm of enterocytes. In control mice treated with normal sheep brain, no PrPc signal was seen in enterocytes of the small intestine. Immunopositivity for neurofilament protein and glial fibrillary acidic protein was seen in the cytoplasm of enterocytes of mice inoculated with scrapie and normal sheep brain. This suggests that the enterocytes of neonatal mice can absorb PrPsc and other macromolecular proteins of the sheep brain affected by scrapie and may be more important than previously thought as a pathway for PrPsc transmission in neonatal animals.