Abstract
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 199.7 ± 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 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 were different from those in C-BSE, 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 reported for that 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 BSE/JP24 prion has newly emerged and showed the possibility that L-type BSE prion might be classified into multiple strains.
Acknowledgements
We thank Ms. Naoko Tabeta, Shuko Kodani, Nozomi Matsumoto, Atsuko Ojima, Ritsuko Miwa and Mutsumi Sakurai for their technical assistance. Further, we thank Dr. Morikazu Shinagawa for his encouragement; Ms. Junko Yamada for her general assistance; and Mr. Manabu Aida, Ms. Chizuru Kuramochi, Che Jing Zh and the animal laboratory staff at the National Institute of Animal Health for maintaining the mouse colony. This study was supported in part by a Grant-in-Aid from the Bovine Spongiform Encephalopathy Control Project of the Ministry of Agriculture, Forestry and Fisheries of Japan; a grant for BSE research from the Ministry of Health, Labour and Welfare of Japan; and a grant-in-aid for the strategic cooperation to control emerging and reemerging infection from the Ministry of Education, Culture, Sports, Science and Technology of Japan.