論文 - 今村 守一
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Oral Transmission of L-type Bovine Spongiform Encephalopathy in Cynomolgus Macaques: Detection of Classical BSE-like Prions in Lymphoid 査読あり
Morikazu Imamura, Ken’ichi Hagiwara, Minoru Tobiume, Minako Ohno, Hiromi Iguchi, Hanae Takatsuki, Tsuyoshi Mori, Ryuichiro Atarashi, Hiroaki Shibata, Fumiko Ono
Emerging Infectious Diseases 2025年
担当区分：筆頭著者, 責任著者 掲載種別：研究論文（学術雑誌）
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Shibata H., Ono F., Sato Y., Ohto K., Nakano N., Imamura M., Horiuchi M., Tobiume M., Hagiwara K.
Microbiology and Immunology 2024年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Microbiology and Immunology
Bovine spongiform encephalopathy (BSE) is a prion disease in cattle caused by classical-type (C-), L-type (L-), or H-type (H-) BSE prions. While C-BSE prions are zoonotic agents responsible for variant Creutzfeldt–Jakob disease, L- and H-BSE prions are believed not to be connected to human prion diseases. However, L-BSE prions have been shown to transmit to cynomolgus monkeys (Macaca fascicularis), suggesting they may have zoonotic potential. In the present study, we examined whether H-BSE prions are transmissible to cynomolgus monkeys. The monkeys were injected intracranially (n = 2) or given orally (n = 2) with brain homogenates from a cow infected with H-BSE prions. After asymptomatic observation periods of 4–6 years, the monkeys were euthanized for autopsy. Histological examination of the brain did not reveal any pathological changes. Immunohistochemical and Western blot analyses did not detect disease-associated forms of prion protein (PrPSc) in the brain, peripheral neurons, or lymphatic tissues. The unsuccessful transmission indicates an effective barrier against the transmission of cattle H-BSE prions to cynomolgus monkeys. Based on the results obtained in this nonhuman primate model, we estimated that the potential transmission of H-BSE prions to humans is substantially lower than C- and L-BSE prions.
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Photocatalytic Inactivation of Viruses and Prions: Multilevel Approach with Other Disinfectants 査読あり
Onodera T., Sugiura K., Haritani M., Suzuki T., Imamura M., Iwamaru Y., Ano Y., Nakayama H., Sakudo A.
Applied Microbiology 2 ( 4 ) 701 - 715 2022年12月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Applied Microbiology
Ag, Cu, Zn, Ti, and Au nanoparticles show enhanced photocatalytic properties. Efficient indoor disinfection strategies are imperative to manage the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Virucidal agents, such as ethanol, sodium hypochlorite, 222-nm UV light, and electrolyzed water inactivate SARS-CoV-2 in indoor environments. Tungsten trioxide (WO3) photocatalyst and visible light disinfect abiotic surfaces against SARS-CoV-2. The titanium dioxide (TiO2)/UV system inactivates SARS-CoV-2 in aerosols and on deliberately contaminated TiO2-coated glass slide surfaces in photocatalytic chambers, wherein 405-nm UV light treatment for 20 min sterilizes the environment and generates reactive oxygen species (ROS) that inactivate the virus by targeting S and envelope proteins and viral RNA. Mesoscopic calcium bicarbonate solution (CAC-717) inactivates pathogens, such as prions, influenza virus, SARS-CoV-2, and noroviruses, in fluids; it presumably acts similarly on human and animal skin. The molecular complexity of cementitious materials promotes the photocatalysis of microorganisms. In combination, the two methods can reduce the pathogen load in the environment. As photocatalysts and CAC-717 are potent disinfectants for prions, disinfectants against prionoids could be developed by combining photocatalysis, gas plasma methodology, and CAC-717 treatment, especially for surgical devices and instruments.
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Pasiana AD, Miyata H, Chida J, Hara H, Imamura M, Atarashi R, and Sakaguchi S.
J Biol Chem 298 ( 9 ) 102381 2022年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Biological Chemistry
Conformational conversion of the cellular prion protein, PrPC, into the amyloidogenic isoform, PrPSc, is a key pathogenic event in prion diseases. However, the conversion mechanism remains to be elucidated. Here, we generated Tg(PrPΔ91-106)-8545/Prnp0/0 mice, which overexpress mouse PrP lacking residues 91-106. We showed that none of the mice became sick after intracerebral inoculation with RML, 22L, and FK-1 prion strains nor accumulated PrPScΔ91-106 in their brains except for a small amount of PrPScΔ91-106 detected in one 22L-inoculated mouse. However, they developed disease around 85 days after inoculation with bovine spongiform encephalopathy (BSE) prions with PrPScΔ91-106 in their brains. These results suggest that residues 91-106 are important for PrPC conversion into PrPSc in infection with RML, 22L, and FK-1 prions but not BSE prions. We then narrowed down the residues 91-106 by transducing various PrP deletional mutants into RML- and 22L-infected cells and identified that PrP mutants lacking residues 97-99 failed to convert into PrPSc in these cells. Our in vitro conversion assay also showed that RML, 22L, and FK-1 prions did not convert PrPΔ97-99 into PrPScΔ97-99, but BSE prions did. We further found that PrP mutants with proline residues at positions 97 to 99 or charged residues at positions 97 and 99 completely or almost completely lost their converting activity into PrPSc in RML- and 22L-infected cells. These results suggest that the structurally flexible and noncharged residues 97-99 could be important for PrPC conversion into PrPSc following infection with RML, 22L, and FK-1 prions but not BSE prions.
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Takatsuki H, Imamura M, Mori T, Atarashi R
Sci Rep 12 ( 1 ) 7923 2022年5月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Scientific Reports
Each prion strain has its own characteristics and the efficacy of anti-prion drugs varies. Screening of prion disease therapeutics is typically evaluated by measuring amounts of protease-resistant prion protein (PrP-res). However, it remains unclear whether such measurements correlate with seeding activity, which is evaluated by real-time quaking-induced conversion (RT-QuIC). In this study, the effects of anti-prion compounds pentosan polysulfate (PPS), Congo red, and alprenolol were measured in N2a58 cells infected with Fukuoka-1 (FK1) or 22L strain. The compounds abolished PrP-res and seeding activity, except for N2a58/FK1 treated with PPS. Interestingly, the seeding activity of N2a58/FK1, which was reduced in the presence of PPS, was not lost and remained at low levels. However, upon removal of PPS, both were gradually restored to their original levels. These results indicate that low-level persistent prion infection keeping measurable seeding activity is induced by PPS in a strain-dependent manner. Furthermore, for protein misfolding cyclic amplification (PMCA), the anti-prion effect of PPS decreased in FK1 compared to 22L, suggesting that the differences occur at the level of the direct conversion. Our findings demonstrate that the advantages of RT-QuIC and PMCA can be exploited for more accurate assessment of therapeutic drug screening, reflecting strain differences.
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Imamura M, Tabeta N, Iwamaru Y, Takatsuki H, Mori T, Atarashi R
Biochem Biophys Res Commun 613 67 - 72 2022年5月
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Biochemical and Biophysical Research Communications
Prion diseases are transmissible and progressive neurodegenerative disorders characterized by abnormal prion protein (PrPSc) accumulation in the central nervous system. Generation of synthetic PrPSc in a cell-free conversion system and examination of its transmissibility to animals would facilitate testing of the protein-only hypothesis and the understanding of the molecular basis of sporadic prion diseases. In this study, we used recombinant prion protein from a baculovirus-insect cell expression system (Bac-rPrP) and insect cell-derived cofactors to determine whether Bac-rPrPSc is spontaneously produced in intermittent ultrasonic reactions. No spontaneous generation of Bac-rPrPSc was observed at 37 °C, but when the reaction temperature was increased to 45 °C, Bac-rPrPSc was generated in all trials. Some Bac-rPrPSc variants were transmissible to mice, but when the reaction was repeated for 40 rounds, the transmissibility was lost. Notably, a variety of Bac-rPrPSc variants, including non-transmissible ones, differing in resistance to proteinase K and cofactor dependence during amplification, was generated under the same experimental conditions, including the same sonication settings and cofactors. However, their characteristics also disappeared after 40 reaction rounds and the variety converged onto a single variant. These results indicate that various Bac-rPrPSc variants with different transmissibility to mice and structural properties are generated, which compete with each other and gradually converge onto a variant with a slightly faster amplification rate.
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Matsuura Y., Miyazawa K., Horiuchi M., Suzuki A., Yokoyama M., Imamura M., Ikeda K., Iwamaru Y.
Microbiology and Immunology 66 ( 5 ) 212 - 215 2022年5月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Microbiology and Immunology
Chronic wasting disease (CWD) is a prion disease affecting cervid species primarily in the United States of America and Canada; however, it is now emerging in Scandinavian countries. Although CWD cases have not been reported in Japan, in case of a CWD outbreak occuring, it is critical to prepare for testing a large number of specimens. The present study showed that a rapid post-mortem test kit, which is used for bovine spongiform encephalopathy surveillance in Japan, is valid for the detection of CWD prion.
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Ethanolamine is a new anti‐prion compound
Uchiyama K., Hara H., Chida J., Pasiana A.D., Imamura M., Mori T., Takatsuki H., Atarashi R., Sakaguchi S.
International Journal of Molecular Sciences 22 ( 21 ) 2021年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：International Journal of Molecular Sciences
Prion diseases are a group of fatal neurodegenerative disorders caused by accumulation of proteinaceous infectious particles, or prions, which mainly consist of the abnormally folded, am-yloidogenic prion protein, designated PrPSc. PrPSc is produced through conformational conversion of the cellular isoform of prion protein, PrPC, in the brain. To date, no effective therapies for prion diseases have been developed. In this study, we incidentally noticed that mouse neuroblastoma N2a cells persistently infected with 22L scrapie prions, termed N2aC24L1‐3 cells, reduced PrPSc levels when cultured in advanced Dulbecco’s modified eagle medium (DMEM) but not in classic DMEM. PrPC levels remained unchanged in prion‐uninfected parent N2aC24 cells cultured in advanced DMEM. These results suggest that advanced DMEM may contain an anti‐prion compound(s). We then successfully identified ethanolamine in advanced DMEM has an anti‐prion activity. Ethanola-mine reduced PrPSc levels in N2aC24L1‐3 cells, but not PrPC levels in N2aC24 cells. Also, oral administration of ethanolamine through drinking water delayed prion disease in mice intracerebrally inoculated with RML scrapie prions. These results suggest that ethanolamine could be a new anti-prion compound.
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Ethanolamine is a new anti-prion compound. 査読あり 国際共著
Uchiyama K, Hara H, Chida J, Pasiana AD, Imamura M, Mori T, Takatsuki H, Atarashi R, Sakaguchi S
Int J Mol Sci 22 ( 21 ) 11742 2021年10月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Strain-dependent prion infection in mice expressing prion protein with deletion of central residues 91-106. 査読あり
Uchiyama K, Miyata H, Yamaguchi Y, Imamura M, Okazaki M, Pasiana AD, Chida J, Hara H, Atarashi R, Watanabe H, Kondoh G, Sakaguchi S
Int J Mol Sci 21 ( 19 ) 7260 2020年10月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Uchiyama K., Miyata H., Yamaguchi Y., Imamura M., Okazaki M., Pasiana A.D., Chida J., Hara H., Atarashi R., Watanabe H., Kondoh G., Sakaguchi S.
International Journal of Molecular Sciences 21 ( 19 ) 1 - 18 2020年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：International Journal of Molecular Sciences
Conformational conversion of the cellular prion protein, PrPC, into the abnormally folded isoform, PrPSc, is a key pathogenic event in prion diseases. However, the exact conversion mechanism remains largely unknown. Transgenic mice expressing PrP with a deletion of the central residues 91–106 were generated in the absence of endogenous PrPC, designated Tg(PrP∆91–106)/Prnp0/0 mice and intracerebrally inoculated with various prions. Tg(PrP∆91–106)/Prnp0/0 mice were resistant to RML, 22L and FK-1 prions, neither producing PrPSc ∆91–106 or prions in the brain nor developing disease after inoculation. However, they remained marginally susceptible to bovine spongiform encephalopathy (BSE) prions, developing disease after elongated incubation times and accumulating PrPSc ∆91–106 and prions in the brain after inoculation with BSE prions. Recombinant PrP∆91-104 converted into PrPSc ∆91–104 after incubation with BSE-PrPSc-prions but not with RML-and 22L–PrPSc-prions, in a protein misfolding cyclic amplification assay. However, digitonin and heparin stimulated the conversion of PrP∆91–104 into PrPSc ∆91–104 even after incubation with RML-and 22L-PrPSc-prions. These results suggest that residues 91–106 or 91–104 of PrPC are crucially involved in prion pathogenesis in a strain-dependent manner and may play a similar role to digitonin and heparin in the conversion of PrPC into PrPSc .
DOI： 10.3390/ijms21197260
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Inactivation of scrapie prions by the electrically charged disinfectant CAC-717. 査読あり
Sakudo A, Iwamaru Y, Furusaki K, Haritani M, Onishi R, Imamura M, Yokoyama T, Yoshikawa Y, Onodera T
Pathogens 9 ( 7 ) E536 - 10 2020年7月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Pathogens
Previous studies have revealed that the electrically charged disinfectant CAC-717 has strong virucidal and bactericidal effects but is safe for humans and animals. In this study, CAC-717 was further evaluated for its potential effects as a disinfectant against scrapie prions. Western blotting showed that CAC-717 reduced the amount of the abnormal isoform of prion protein (PrPSc) in prion-infected cell (ScN2a) lysates. Furthermore, the reduction of prion transmissibility was confirmed by a mouse bioassay, in which mice injected with scrapie prions pre-treated with CAC-717 survived longer than those injected with untreated scrapie prions. Lastly, to evaluate the seeding activity of ScN2a cell lysates treated with CAC-717, quantitative protein misfolding cyclic amplification (PMCA) was performed directly on ScN2a cell lysates treated with CAC-717, which showed that the median dose of PMCA (PMCA50) dropped from log9.95 to log5.20 after CAC-717 treatment, indicating more than a 4 log reduction. This suggests that the seeding activity of PrPSc is decreased by CAC-717. Collectively, these results suggest that CAC-717 has anti-prion activity, reducing both PrPSc conversion activity and prion transmissibility; thus, CAC-717 will be useful as a novel disinfectant in prion diseases.
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First case of atypical scrapie in a goat in Japan. 査読あり
Matsuura Y, Miyazawa K, Imamura M, Yokoyama T, Iwamaru Y
J Vet Med Sci 81 ( 7 ) 986 - 989 2019年7月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Experimental infection of cattle with a novel prion derived from atypical H-type bovine spongiform encephalopathy. 査読あり
Okada H., Masujin K., Miyazawa K., Iwamaru Y., Imamura M., Matsuura Y., Arai S., Fukuda S., Murayama Y., Yokoyama T.
Vet. Pathol. 54 ( 6 ) 892 - 900 2017年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Self-propagating, protease-resistant, recombinant prion protein conformers with or without in vivopathogenicity. 査読あり
Wang F., Wang X., Orrú CD., Groveman BR., Surewicz K., Abskharon R., Imamura M., Yokoyama T., Kim YS., Vander Stel KJ., Sinniah K., Priola SA., Surewicz WK., Caughey B., Ma J.
PLoS Pathog. 13 ( 7 ) e1006491 2017年7月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Oral transmission of L-Type bovine spongiform encephalopathy agent among cattle. 査読あり
Okada H.*, Iwamaru Y., Imamura M., Miyazawa K., Matsuura Y, Masujin K., Murayama Y., Yokoyama T.
Emerging infectious diseases 23 ( 2 ) 284 - 287 2017年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Identification of the first case of atypical scrapie in Japan. 査読あり
Imamura M., Miyazawa K.*, Iwamaru Y., Matsuura Y., Yokoyama T., Okada H.
The Journal of veterinary medical 78 ( 12 ) 1915 - 1919 2017年1月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1292/jvms.16-0379
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Multiple affinity purification of a baculovirus-derived recombinant prion protein with in vitro ability to convert to its pathogenic form. 査読あり
Imamura M.*, Kato N., Iwamaru Y., Mohri S., Yokoyama T.Murayama Y.
Preparative biochemistry & biotechnology 47 ( 1 ) 1 - 7 2017年1月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Heparan sulfate and heparin promote faithful prion replication in vitro by binding to normal and abnormal prion proteins in protein misfolding cyclic amplification. 査読あり
Imamura M.*, Tabeta N., Kato N., Matsuura Y., Iwamaru Y., Yokoyama T., Murayama Y.
The Journal of biological chemistry 291 ( 51 ) 26478 - 26486 2016年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Transmission of atypical scrapie to homozygous ARQ sheep. 査読あり
Okada H.*, Miyazawa K., Imamura M., Iwamaru Y., Masujin K., Matsuura Y., Yokoyama T.
The Journal of veterinary medical science 78 ( 10 ) 1619 - 1624 2016年11月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1292/jvms.16-0259