title: Subcritical Water Hydrolysis Effectively Reduces the In Vitro Seeding Activity of PrPSc but Fails to Inactivate the Infectivity of Bovine Spongiform Encephalopathy Prions.
abstract: The global outbreak of bovine spongiform encephalopathy (BSE) has been attributed to the recycling of contaminated meat and bone meals (MBMs) as feed supplements. The use of MBMs has been prohibited in many countries; however, the development of a method for inactivating BSE prions could enable the efficient and safe use of these products as an organic resource. Subcritical water (SCW), which is water heated under pressure to maintain a liquid state at temperatures below the critical temperature (374°C), exhibits strong hydrolytic activity against organic compounds. In this study, we examined the residual in vitro seeding activity of protease-resistant prion protein (PrPSc) and the infectivity of BSE prions after SCW treatments. Spinal cord homogenates prepared from BSE-infected cows were treated with SCW at 230-280°C for 5-7.5 min and used to intracerebrally inoculate transgenic mice overexpressing bovine prion protein. Serial protein misfolding cyclic amplification (sPMCA) analysis detected no PrPSc in the SCW-treated homogenates, and the mice treated with these samples survived for more than 700 days without any signs of disease. However, sPMCA analyses detected PrPSc accumulation in the brains of all inoculated mice. Furthermore, secondary passage mice, which inoculated with brain homogenates derived from a western blotting (WB)-positive primary passage mouse, died after an average of 240 days, similar to mice inoculated with untreated BSE-infected spinal cord homogenates. The PrPSc accumulation and vacuolation typically observed in the brains of BSE-infected mice were confirmed in these secondary passage mice, suggesting that the BSE prions maintained their infectivity after SCW treatment. One late-onset case, as well as asymptomatic but sPMCA-positive cases, were also recognized in secondary passage mice inoculated with brain homogenates from WB-negative but sPMCA-positive primary passage mice. These results indicated that SCW-mediated hydrolysis was insufficient to eliminate the infectivity of BSE prions under the conditions tested.
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.|Research Area of Pathology and Pathophysiology, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Miyako
authors.initials: M
authors.lastname: Yoshioka
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okada
authors.affiliation: Department of Agro-environmental Sciences, Faculty of Agriculture, Kyushu University, Fukuoka, Fukuoka, Japan.|Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Takata
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Masujin
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Iwamaru
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimozaki
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Yamamura
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokoyama
authors.affiliation: Influenza/Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.|Department of Neurological Science, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
authors.forename: Shirou
authors.initials: S
authors.lastname: Mohri
authors.affiliation: Department of Agro-environmental Sciences, Faculty of Agriculture, Kyushu University, Fukuoka, Fukuoka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tsutsumi
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D004203:Disinfection / Q000379:methods*; D016643:Encephalopathy, Bovine Spongiform / Q000378:metabolism* / Q000635:transmission; D005506:Food Contamination; D023421:Models, Animal; D018620:PrPSc Proteins / Q000378:metabolism*; D000069466:Red Meat
chemical_list: D018620:PrPSc Proteins