{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,19]],"date-time":"2026-07-19T02:52:19Z","timestamp":1784429539951,"version":"3.55.0"},"reference-count":42,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,10,31]],"date-time":"2025-10-31T00:00:00Z","timestamp":1761868800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Vet. Sci."],"abstract":"\n Background<\/jats:title>\n \n Fish nocardiosis caused by\n Nocardia seriolae<\/jats:italic>\n is a severe bacterial disease in aquaculture, causing significant economic losses. The effectiveness of antibiotics in dealing with nocardiosis induced by\n N. seriolae<\/jats:italic>\n is not satisfactory. NsICL is a potential virulence factor in\n N. seriolae<\/jats:italic>\n based on its crucial role in the glyoxylate cycle, its identity as a secreted protein, and its established role in virulence and intracellular survival in homologous pathogens such as\n Mycobacterium tuberculosis<\/jats:italic>\n . so, the NS-\u0394ICL deletion strain was constructed to investigate its function.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n The\n NsICL<\/jats:italic>\n gene was knocked out via homologous recombination to generate the mutant strain NS-\u0394ICL. Comparative analysis of morphology, growth, and virulence was performed between the mutant and wild-type strains. The NS-\u0394ICL strain was used to immunize hybrid snakehead (\n Channa maculata<\/jats:italic>\n \u2640 \u00d7\n Channa argus<\/jats:italic>\n \u2642), with immune responses evaluated through non-specific immune parameters, specific antibodies, and expression levels of immune-related genes. Protective efficacy was assessed by challenge tests.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n NS-\u0394ICL showed reduced virulence (LD\n 50<\/jats:sub>\n = 2.60 \u00d7 10\n 5<\/jats:sup>\n cfu\/fish) compared to the wild-type strain (LD\n 50<\/jats:sub>\n = 4.32 \u00d7 10\n 4<\/jats:sup>\n cfu\/fish). Immunized fish exhibited significantly higher levels of non-specific immune factors (AKP, ACP, POD, LZM) and specific IgM antibodies. Immune-related genes (\n MHCI<\/jats:italic>\n \u03b1,\n CD4, IL-8<\/jats:italic>\n ) were upregulated in vaccinated fish. Relative percentage survival (RPS) was 77.03% in vaccinated fish after challenge tests, which indicating strong protective efficacy.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n \n The NS-\u0394ICL deletion strain was successfully constructed in this study. It can not only induce humoral and cellular immunity in fish but also effectively protect fish against\n N. seriolae<\/jats:italic>\n infection. These results provide a foundation for the development of a live attenuated vaccine for treating fish nocardiosis.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fvets.2025.1664034","type":"journal-article","created":{"date-parts":[[2025,10,31]],"date-time":"2025-10-31T05:24:17Z","timestamp":1761888257000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["An isocitrate lyase gene-deleted strain of Nocardia seriolae in live attenuated vaccine development against fish nocardiosis"],"prefix":"10.3389","volume":"12","author":[{"given":"Guanying","family":"Lin","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yan","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Suying","family":"Hou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yiming","family":"Wen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoya","family":"Lei","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ting","family":"Huang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuben","family":"Chen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianlin","family":"Chen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liqun","family":"Xia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,10,31]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"4901","DOI":"10.1111\/are.15988","article-title":"Pathogenicity, diagnosis, prevention strategies and immune response of bacterium Nocardia seriolae: a critical review","volume":"53","author":"Nawaz","year":"2022","journal-title":"Aquac Res."},{"key":"B2","doi-asserted-by":"publisher","first-page":"659","DOI":"10.1128\/jb.58.5.659-664.1949","article-title":"A streptomycete pathogenic to fish","volume":"58","author":"Rucker","year":"1949","journal-title":"J bacterial."},{"key":"B3","doi-asserted-by":"publisher","first-page":"e00656","DOI":"10.1002\/mbo3.656","article-title":"Ha Sm, Yang SJ, Kim JD, Cho Kh, et al. 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