Electron microscopic and confocal laser microscopy analysis of amyloid plaques in chronic wasting disease transmitted to transgenic mice.

We report here on the ultrastructure of amyloid plaques in chronic wasting disease (CWD) transmitted to Tg20 transgenic mice overexpressing prion protein (PrP). We identified three main types of amyloid deposits in mCWD: large amyloid deposits, unicentric plaques similar to kuru plaques in human prion diseases and multicentric plaques reminiscent of plaques typical of GSS. The most unique type of plaques were large subpial amyloid deposits. They were composed of large areas of amyloid fibrils but did not form "star-like" appearances of unicentric plaques. All types of plaques were totally devoid of dystrophic neuritic elements. However, numerous microglial cells invaded them. The plaques observed by confocal laser microscope were of the same types as those analyzed by electron microscopy. Neuronal processes surrounding the plaques did not show typical features of neuroaxonal dystrophy.