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• Pathogenesis of Vibrio cholerae

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• Fermentation products of the fungus Monascus spp. impairs the physiological activities of toxin-producing Vibrio cholerae

  Jun Xu, Rino Arakaki, Shinjiro Tachibana, Tetsu Yamashiro

  Microbiological Research ( Elsevier BV )  258   126995   2022.05 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Monascus spp. are filamentous fungi used in fermented foods. They are also natural colorants and food preservatives. Certain metabolites of Monascus spp. lower cholesterol and have other health-promoting effects in humans. In the present study, we demonstrated that the fermentation products of Monascus spp. inhibited ATP synthesis and motility in toxigenic Vibrio cholerae. Single-cell tracking and rotation assays on single flagella showed that Monascus fermentation extract (MFE) significantly impaired V. cholerae swimming by disrupting flagellar rotation. A membrane potential-sensitive carbocyanine dye revealed that MFE depolarized the V. cholerae cell membrane which, in turn, lowered the membrane potential and, by extension, restricted ATP synthesis and flagellar rotation. MFE also severely hindered the motility of other pathogenic bacteria such as V. parahaemolyticus, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, and Leptospira interrogans. The foregoing findings indicate that Monascus fermentation extract could potentially preventing infection caused by multiple pathogenic bacteria as the conventional prophylaxes and slow their progression and lower mortality and morbidity.

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• Analysis of human clinical and environmental Leptospira to elucidate the eco-epidemiology of leptospirosis in Yaeyama, subtropical Japan

  Yukuto Sato , Idam Hermawan , Tetsuya Kakita , Sho Okano , Hideyuki Imai , Hiroto Nagai , Ryosuke Kimura , Tetsu Yamashiro , Tadashi Kajita , Claudia Toma

  PLOS Neglected Tropical Diseases ( Public Library of Science (PLoS) )  16 ( 3 ) e0010234 - e0010234   2022.03 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Background Leptospirosis, a zoonosis caused by species in the spirochete genus Leptospira, is endemic to the Yaeyama region in Okinawa, subtropical Japan. Species of the P1 subclade “virulent” group, within the genus Leptospira, are the main etiological agents of leptospirosis in Okinawa. However, their environmental persistence is poorly understood. This study used a combination of bacterial isolation and environmental DNA (eDNA) metabarcoding methods to understand the eco-epidemiology of leptospirosis in this endemic region. Findings Polymerase chain reaction (PCR) characterized twelve human clinical L. interrogans isolates belonging to the P1 subclade “virulent” subgroup and 11 environmental soil isolates of the P1subclade “low virulent” subgroup (genetically related to L. kmetyi, n = 1; L. alstonii, n = 4; L. barantonii, n = 6) from the Yaeyama region targeting four virulence-related genes (lipL32, ligA, ligB and lpxD1). Clinical isolates were PCR positive for at least three targeted genes, while all environmental isolates were positive only for lipL32. Analysis of infected renal epithelial cells with selected clinical and environmental strains, revealed the disassembly of cell-cell junctions for the Hebdomadis clinical strain serogroup. Comparison of leptospiral eDNA during winter and summer identified operational taxonomic units corresponding to the species isolated from soil samples (L. kmetyi and L. barantonii) and additional P2 subclade species (L. licerasiae, L. wolffii-related, among others) that were not detected by soil cultivation. Total Leptospira read counts were higher in summer than in winter and the analysis of leptospiral/animal eDNA relationship suggested Rattus spp. as a potential reservoir animal. Conclusion Our study demonstrated high environmental Leptospira diversity in the Yaeyama region, particularly during summer, when most of the leptospirosis cases are reported. In addition, several Leptospira species with pathogenic potential were identified that have not yet been reported in Yaeyama; however, the environmental persistence of P1 subclade species previously isolated from human clinical cases in this region was absent, suggesting the need of further methodology development and surveillance.

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• Risk Factors Associated with Diarrheal Episodes in an Agricultural Community in Nam Dinh Province, Vietnam: A Prospective Cohort Study.

  Hanako Iwashita , Asako Tokizawa , Vu Dinh Thiem , Taichiro Takemura , Tuan Hai Nguyen , Hang Thi Doan , Anh Hong Quynh Pham , Na Ly Tran , Tetsu Yamashiro

  International journal of environmental research and public health     2022.02 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Disassembly of the apical junctional complex during the transmigration of Leptospira interrogans across polarized renal proximal tubule epithelial cells

  Isabel Sebastián , Nobuhiko Okura , Bruno M. Humbel , Jun Xu , Idam Hermawan , Chiaki Matsuura , Malgorzata Hall , Chitoshi Takayama , Tetsu Yamashiro , Shuichi Nakamura , Claudia Toma

  Cellular Microbiology     2021.05 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

• Immunological Responses to Seoul Orthohantavirus in Experimentally and Naturally Infected Brown Rats (Rattus norvegicus)

  Shumpei P. Yasuda , Kenta Shimizu , Takaaki Koma , Nguyen Thuy Hoa , Mai Quynh Le , Zhuoxing Wei , Devinda S. Muthusinghe , Sithumini M. W. Lokupathirage , Futoshi Hasebe , Tetsu Yamashiro , Jiro Arikawa , Kumiko Yoshimatsu

  Viruses     2021.04 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• Grant-in-Aid for Scientific Research(A)

  Project Year: 2016.04  -  2020.03 

  Direct: 31,700,000 (YEN)  Overheads: 9,510,000 (YEN)  Total: 41,210,000 (YEN)