Extraneural manifestations of prion infection in GPI-anchorless transgenic mice.

Earlier studies indicated that transgenic (tg) mice engineered to express prion protein (PrP) lacking the glycophosphatidylinositol (GPI⁻/⁻) membrane anchor formed abnormal proteinase-resistant prion (PrPsc) amyloid deposits in their brains and hearts when infected with the RML strain of murine scrapie. In contrast, RML scrapie infection of normal mice with a GPI-anchored PrP did not deposit amyloid with PrPsc in the brain or the heart. Here we report that scrapie-infected GPI⁻/⁻ PrP tg mice also deposit PrP and transmissible infectious material in the gut, kidneys, and islets of Langerhans. Similar to previously reported amyloid deposits in the brain and heart, amyloid deposits were found in the gut; however, no amyloid deposited in the islets. By high-resolution electron microscopy, we show PrP is located primarily in α cells and also β cells. Islets contain abundant insulin and there is no abnormality in glucose metabolism in infected GPI⁻/⁻ PrP tg mice.