A case of L-type-like atypical bovine spongiform encephalopathy was detected in 14-year-old Japanese black beef cattle (BSE/JP24). To clarify the biological and biochemical properties of the prion in BSE/JP24, we performed a transmission study with wild-type mice and bovinized transgenic mice (TgBoPrP). The BSE/JP24 prion was transmitted to TgBoPrP mice with the incubation period of 197.7 ± 3.4 days, which was shorter than that of classical BSE (C-BSE) (223.5 ± 13.5 days). Further, C-BSE was transmitted to wild-type mice with the incubation period of about 409 days, whereas BSE/JP24 prion-inoculated mice showed no clinical signs of BSE for up to 649 days. Severe vacuolation and a widespread and uniform distribution of PrPSc were pathologically observed in the brain of BSE/JP24 prion-affected TgBoPrP mice. The molecular weight and glycoform ratio of PrPSc in BSE/JP24 mice were different from those in C-BSE mice, and PrPSc in BSE/JP24 exhibited weaker proteinase K resistance than that in C-BSE. These findings revealed that the BSE/JP24 prion has distinct biological and biochemical properties compared to those of C-BSE. Interestingly, a shorter incubation period was observed at the subsequent passage of the BSE/JP24 prion to TgBoPrP mice (152.2 ± 3.1 days). This result implies that the BSE/JP24 prion has newly emerged and shows that the L-type BSE prion might be classified into multiple strains.
(Research Team for Prion Diseases, TEL +81-29-838-7708)
Masujin, K., et al. (2008) Prion 2: 123-128.