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Affiliation |
Faculty of Agriculture Department of Marine Biological and Environmental Science |
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External Link |
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NISHIKI Issei
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Research Areas 【 display / non-display 】
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Life Science / Aquatic bioproduction science
Papers 【 display / non-display 】
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Pathogenicity of <i>Lactococcus garvieae</i> serotype III against yellowtail <i>Seriola quinqueradiata</i> and striped jack <i>Pseudocaranx dentex</i>
Fish Pathology 59 ( 1 ) 33 - 35 2024.3
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Society of Fish Pathology
DOI： 10.3147/jsfp.59.33
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Emerging New Serotype <i>Lactococcus garvieae </i>Infection in Farmed Marine Fish in Japan Reviewed
Minami Takayuki, Yoshida Terutoyo, Nishiki Issei
Fish Pathology 58 ( 4 ) 146 - 152 2023.12
Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Society of Fish Pathology
Mortalities due to <i>Lactococcus garvieae</i>-like infection have been observed in farmed greater amberjack <i>Seriola dumerili</i> previously immunized with a commercial <i>L. garvieae</i> vaccine containing serotype I and II strains in Miyazaki Prefecture since August 2021. The isolates from diseased fish were not agglutinated by the anti-serotype I and II sera, and showed genetic similarity to <i>L. garvieae</i> serotype I in multi-locus sequence (16S rRNA gene, <i>pheS</i>, <i>recA</i>, <i>rpoA</i> and <i>rpoB</i>) analysis. The pathogenicity of isolates was confirmed by intraperitoneal injection in greater amberjack, and the lethal dose fifty was less than 1.6 × 10<sup>3</sup> CFU/FISH. In a vaccine trial, greater amberjack, which had been immunized with formalin-killed cells (FKC) prepared from both serotype I and II strains, was not effectively protected against an isolate from this study, whereas those immunized with FKC prepared using the isolate were effectively protected against the infection with an isolate exhibiting the same antigenicity. Based on these findings, we propose a new serotype: serotype III, which is not agglutinated with both anti-serotype I and II serum and not protected against a serotype I and serotype II-combined vaccine.
DOI： 10.3147/jsfp.58.146
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Resistance and genomic characterization of a plasmid pkh2101 harbouring erm(B) isolated from emerging fish pathogen Lactococcus garvieae serotype II in Japan. Reviewed
Akmal M, Akatsuka M, Nishiki I, Yoshida T
Journal of fish diseases 46 ( 8 ) 841 - 848 2023.8
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Shi Yin-Ze, Nishiki Issei, Yoshida Terutoyo
魚病研究 58 ( 2 ) 48 - 59 2023.6
Language：English Publishing type：Research paper (scientific journal) Publisher：日本魚病学会
This study aimed to elucidate the genetic characteristics of lincomycin (LCM) resistance in the absence of erythromycin (EM) resistance in fish pathogenic <i>Lactococcus</i> <i>garvieae</i> serotype I. Two novel <i>lsa</i>(D) variants were found in clinically LCM-sensitive and resistant strains. The amino acid sequences of the two Lsa(D) variants shared 94.77% identity with that of Lsa(D) in <i>L</i>. <i>garvieae</i> serotype II. One of the <i>lsa</i>(D) variants, designated as <i>lsa</i>(D)<i><sup>36A</sup></i>, conferred cross-resistance to lincosamides, streptogramins A, and pleuromutilin, which was defined as the LS<sub>A</sub>P-resistant phenotype. This phenotype was confirmed by the minimum inhibitory concentrations of the <i>lsa</i>(D)<i><sup>36A</sup></i>-disruption mutant Δ<i>lsa</i>(D)<i><sup>36A</sup></i>, and its complementation strain. However, a single-point mutation, which led to an amino acid substitution, was found in <i>lsa</i>(D)<i><sup>36D</sup></i> in clinically LS<sub>A</sub>P-sensitive strains. In addition, single-nucleotide replacement of <i>lsa</i>(D)<i><sup>36D</sup></i> alleles was identified in laboratory-induced LCM-resistant mutants. Meanwhile, the <i>lsa</i>(D)<i><sup>36D</sup></i> or <i>lsa</i>(D)<i><sup>36A</sup></i> was also detected in EM-resistant strains carrying <i>erm</i>(B). These strains carried <i>lsa</i>(D)<i><sup>36D</sup></i> with <i>erm</i>(B) or <i>lsa</i>(D)<i><sup>36A</sup></i> with <i>erm</i>(B), which conferred the EM- and LCM-resistant (ML-resistant) or MLS<sub>A</sub>P-resistant phenotype, respectively. In conclusion, <i>lsa</i>(D)<i><sup>36D</sup></i> was an intrinsic in the LS<sub>A</sub>P-sensitive <i>L</i>. <i>garvieae</i> serotype I, and its mutated allelic variant was named as <i>lsa</i>(D)<i><sup>36A</sup></i>, which explains the characteristic resistance of this strain to the LS<sub>A</sub>P-resistance phenotype.
DOI： 10.3147/jsfp.58.48
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<i>Vibrio anguillarum</i> J-O-1 Type Infection in Farmed Greater Amberjack <i>Seriola dumerili</i> Reviewed
Minami Takayuki, Tawara Yusei, Hirokawa Yusuke, Nishiki Issei
Fish Pathology 57 ( 4 ) 131 - 135 2023.1
Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Society of Fish Pathology
Mortalities were observed in farmed greater amberjack <i>Seriola dumerili</i> immunized with a commercial <i>Vibrio anguillarum</i> serotype J-O-3 vaccine. Symptoms of infection included extruded eye, opacity of cornea, exfoliation of head epithelium and operculum redding. Bacteria isolated from infected fish were identified as <i>V. anguillarum</i> serotype J-O-1 based on APE20E, anti <i>V. anguillarum</i> J-O-1 serum, species-specific multiplex PCR assays, and 16S rRNA sequence analysis. Experimental infection revealed that the isolate was pathogenic to greater amberjack. In a vaccine trial, mortality of fish immunized with formalin-killed cells (FKC) of the isolate was significantly lower than that of control fish, suggesting that FKC of the isolate prevents greater amberjack from <i>V. anguillarum</i> serotype J-O-1 infection.
DOI： 10.3147/jsfp.57.131
Presentations 【 display / non-display 】
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Lactococcus garvieae III型の遺伝学的解析
西木一生・北村 大・吉田照豊
令和5年度日本魚病学会春季大会
Event date： 2023.3.14 - 2023.3.15
Presentation type：Poster presentation
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海産養殖魚におけるαレンサ球菌症原因細菌の同定方法の開発
毛利文香・西木一生・吉田照豊
令和4年度日本水産学会九州支部大会
Event date： 2023.1.7
Language：Japanese Presentation type：Oral presentation (general)
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海面養殖魚から分離した血清型不明の Lactococcus garvieae に関する研究 I
俵 佑誠・南 隆之・西木一生・吉田照豊
令和4年度日本魚病学会春季大会
Event date： 2022.3.5 - 2022.3.6
Presentation type：Oral presentation (general)
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Lactococcus garvieae Ⅱ 型の薬剤感受性に関する研究
Muhammad Akmal・阿部京香・西木一生・吉田照豊
令和4年度日本魚病学会春季大会
Event date： 2022.3.5 - 2022.3.6
Presentation type：Oral presentation (general)
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国内で分離された Lactococcus garvieae II 型株の遺伝学的特性および抗原性に関する研究
嶋原佳子・高野倫一・中川徹優・佐藤 純・中易千早・釜石 隆・福田耕平・高野良子・西木 一生
令和4年度日本魚病学会春季大会
Event date： 2022.3.5 - 2022.3.6
Presentation type：Oral presentation (general)
Grant-in-Aid for Scientific Research 【 display / non-display 】
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新型Lactococcus garvieae感染症の疫学調査およびワクチン開発に関する研究
Grant number：23K05396 2023.04 - 2026.03
独立行政法人日本学術振興会 科学研究費基金 基盤研究(C)
Authorship：Principal investigator
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ノカルジアの魚類マクロファージ内における生存戦略に関する研究
Grant number：18K05805 2018 - 2023
独立行政法人日本学術振興会 科学研究費基金 基盤研究(C)
Authorship：Coinvestigator(s)