Two different scrapie prion strains with different characteristics were obtained from two sheep naturally infected with scrapie in Japan. In mice transmission, one (Tsukuba-1) showed shorter incubation periods (133±2 days) than the other (Tsukuba-2) (288±5 days). Spongiform changes and accumulation of an abnormal isoform of prion protein (PrPSc) were observed throughout the brain in Tsukuba-1 inoculated mice, while the lesions and the PrPSc accumulation were localized in the brain stem of mice with Tsukuba-2. A super-infection experiment revealed that neither strain interfered with the other's propagation.
(Prion Research Team, Prion Disease Research Center TEL +81-29-838-7757)
References:
Hirogari et al. (2003) Microbiol. Immunol. 47:871-876.