Journal of fish diseases最新文献

{"title":"Outbreaks of Granulomatous Disease Associated With Vibrio harveyi Infection in Grouper (Epinephelus fuscoguttatus × E. lanceolatus) Aquaculture in Taiwan","authors":"Shang-Ting Wu,&nbsp;Chia-Yu Hsieh","doi":"10.1111/jfd.70213","DOIUrl":"10.1111/jfd.70213","url":null,"abstract":"<p>Between 2015 and 2024, outbreaks of muscular and visceral granulomatous disease, resulting in moderate-to-severe mortality in farmed groupers, occurred in southern Taiwan. Initially, affected groupers were screened for granuloma-associated pathogens, including <i>Mycobacterium</i> spp., <i>Nocardia</i> spp., <i>Photobacterium damselae</i> and <i>Edwardsiella</i> spp., using PCR methods at local animal disease prevention and control centres. Twenty-five hybrid groupers (<i>Epinephelus fuscoguttatus</i> × <i>E. lanceolatus</i>) that tested negative for these pathogens were submitted to our laboratory for further examination. Infected fish exhibited multiple grey-white nodules on the body surface and visceral organs, particularly the kidneys. Large numbers of Gram-negative bacilli, measuring 2–3 μm in length, were observed in organ smears. Microscopic examination revealed multifocal granulomatous lesions in the subcutaneous muscle, kidneys, spleen and liver. Sequencing of the 16S rRNA gene and the <i>Vibrio harveyi</i> hemolysin (<i>vhh</i>) gene from all isolates confirmed their identity as <i>V. harveyi</i>. The pathogen was definitively localised within the lesions via in situ hybridisation using a digoxigenin (DIG)-labelled probe. This is the first report of natural <i>V. harveyi</i> infection causing muscular and visceral granulomatous disease in Taiwanese grouper farms. These findings underscore the emerging pathological relevance of <i>V. harveyi</i> and provide a practical diagnostic framework for granulomatous diseases in aquaculture.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfd.70213","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147987722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Renal Trichodinosis in the Japanese Rice Fish, Oryzias latipes: First Report and Phylogenetic Classification","authors":"J. Harl,&nbsp;K. Lipnik,&nbsp;S. Thalguter,&nbsp;E. Lewisch","doi":"10.1111/jfd.70212","DOIUrl":"10.1111/jfd.70212","url":null,"abstract":"<p>Investigation of a disease outbreak in a hobbyist's medaka (<i>Oryzias latipes</i>) collection led to the detection of <i>Trichodina</i> sp. in the kidney tubuli of individual fish. Based on this observation, a thorough clinical workup, including native microscopy, histopathology and molecular genetics, was conducted. Besides the trichodinids, <i>Ichtyobodo necator</i> and microsporidian gill infection were found in one out of the eight fish, and all of them were infected with <i>Mycobacterium</i> sp. Morphological description of the renal <i>Trichodina</i> sp. was based on the parasites found in renal tubules. For molecular genetic characterization and phylogenetic analysis, primers targeting the 18S rRNA gene of all members of the order Mobilida were designed. The phylogenetic analysis of the 18S rRNA sequences showed a close relationship to <i>Trichodina ruditapicis</i> (FJ499385), <i>Trichodina glossogobae</i> (ON042773) and <i>Trichodina sinonovaculae</i> (FJ499386) sampled from fish and mussels in China, differing by 2.2%–2.5%. Here we report for the first time renal trichodinosis of <i>O. latipes</i> and molecular data of a fish-endozoic <i>Trichodina</i> sp.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfd.70212","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148143556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enrichment-Based Duplex PCR for Early Detection of Potentially Virulent Vibrio harveyi in Aquaculture","authors":"Javier Barriga-Cuartero,&nbsp;Carla Hernández-Cabanyero,&nbsp;Pablo Ibanyez-Paya,&nbsp;Carmen Amaro,&nbsp;Belen Fouz","doi":"10.1111/jfd.70224","DOIUrl":"10.1111/jfd.70224","url":null,"abstract":"<p><i>Vibrio harveyi</i> is an important bacterial pathogen in marine aquaculture, responsible for outbreaks affecting a wide range of fish species. Early detection of potentially virulent isolates in fish and environmental samples is essential for effective disease prevention and management, particularly under field conditions where the pathogen may be present at low abundance. In this study, we developed and evaluated the analytical and diagnostic performance of a two-step detection protocol that combines a short alkaline peptone water (APW-1) enrichment step with a duplex PCR assay targeting the species-specific <i>toxR</i> gene and the plasmid-associated <i>fpcrp</i> gene, a putative marker linked to increased virulence in some fish-pathogenic vibrios. This marker was detected in a diverse set of publicly available genomes from virulent <i>V. harveyi</i> isolates as well as in virulent isolates used in this study. This integrated approach enables reliable detection of <i>V. harveyi</i> in complex biological and environmental matrices while simultaneously providing virulence-associated screening. The duplex PCR showed high analytical specificity for <i>V. harveyi</i> based on <i>toxR</i> amplification when tested against a panel of closely related <i>Vibrio</i> species and allowed the identification of <i>V. harveyi</i> isolates carrying the putative virulence-associated marker. Without enrichment, the limit of detection was approximately 10⁵ CFU/g or CFU/mL in fish tissues and water samples, whereas incorporation of an 8 h APW-1 enrichment step improved the analytical sensitivity to around 10² CFU/g or CFU/mL. The diagnostic performance of the complete two-step protocol was evaluated using experimentally spiked samples and field samples from Mediterranean aquaculture settings, including fish tissues and aquatic environments. Overall, this enrichment-duplex PCR assay provides a rapid, sensitive and practical tool for the early detection and risk-oriented monitoring of potentially virulent <i>V. harveyi</i> isolates in aquaculture environments, supporting surveillance programmes and control strategies.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfd.70224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148308446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Passive Protective Effects of Chicken Egg Yolk Immunoglobulins (IgY) Against Anguillid Herpesvirus Infection in American Eel (Anguilla rostrata)","authors":"Ying-Ying Li,&nbsp;Qiang Chen,&nbsp;Wen-Zhong Chen,&nbsp;Jin-Xian Yang,&nbsp;Jun-Qing Ge","doi":"10.1111/jfd.70230","DOIUrl":"10.1111/jfd.70230","url":null,"abstract":"<div>\u0000 \u0000 <p>Anguillid herpesvirus (AngHV) is the causative agent of ‘mucus sloughing and hemorrhagic septicemia disease’ in eels. Egg yolk immunoglobulin (IgY) has been reported to serve as oral administration of antibodies against bacterial and viral pathogens. In this study, an inactivated vaccine of AngHV was developed to immunise the laying hens, thereby facilitating the production of anti-AngHV IgY. The yolks were subsequently collected and processed into a dry yolk powder, and IgY was extracted from the yolk powder. The anti-AngHV efficacy of the IgY was assessed through both in vitro and in vivo assays. In vitro analyses showed that the purified IgY was capable of neutralizing AngHV in an antibody concentration-dependent manner. In the in vivo experiment, the incorporation of 6‰ yolk powder into the diet of eels exhibited no negative impact on growth performance, intestinal tissue morphology, intestinal microbiota, and metabolic profiles. However, the incidence of morbidity in AngHV-infected eels decreased from 100% to 71%, while mortality rates declined from 57.14% to 28.57%. Additionally, the concentration of AngHV in the skin mucus was significantly reduced. This study provides the evidence that the anti-AngHV IgY can effectively confer protection to eels against AngHV infection, thereby establishing a foundation for the development of anti-AngHV therapy products using the yolk powder.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148375907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficacy of Ultraviolet Light Disinfection of the Waterborne Microsporidian Pathogen Ecytonucleospora hepatopenaei (EHP)","authors":"Yuan Wang,&nbsp;Shi-ting Lin,&nbsp;Xi-yu Jin,&nbsp;Juan Zhang,&nbsp;Zong-qin Yuan,&nbsp;Assaf Lowenthal,&nbsp;Hong-xin Tan","doi":"10.1111/jfd.70221","DOIUrl":"10.1111/jfd.70221","url":null,"abstract":"<div>\u0000 \u0000 <p>The microsporidian <i>Ecytonucleospora hepatopenaei</i> (EHP) is an environmentally persistent, waterborne pathogen that threatens global shrimp aquaculture. This study evaluated the effectiveness of medium-pressure ultraviolet (MPUV) irradiation for disinfecting the unculturable EHP spores in water. Spore viability was assessed using a modified dual-fluorescence staining method. MPUV-induced DNA damage of spores was evaluated through both conventional PCR and quantitative PCR (qPCR) targeting the spore wall protein (SWP1) and small subunit ribosomal RNA (SSU) genes. Results showed that MPUV irradiation induced a significant, dose-dependent inactivation of EHP spores. A low dose of 27.6 mJ/cm² did not significantly increase mortality compared to the control, whereas doses of 55.2–273.0 mJ/cm² produced progressively higher mortality. At intermediate exposures, some spores initiated but failed to complete polar tube ejection, forming only small buds, indicating the loss of infectivity. High doses of 216.0 and 273.0 mJ/cm² yielded spore mortality rates of 95.67% and 97.14%, respectively, with no spore germination or budding observed. Molecular analyses confirmed that substantial DNA damage in EHP spores and suggested that the SWP1 gene is a more reliable indicator of this damage than the SSU gene. These findings establish MPUV as an effective, chemical-free disinfection strategy, providing practical dosing guidelines for preventing EHP transmission in water treatment and aquaculture biosecurity.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148308430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification, Molecular Characterisation, Expression and Functional Analysis of FADD in Response to Streptococcus agalactiae Infection in Nile Tilapia","authors":"Jingjing Ran,&nbsp;Hui Du,&nbsp;Longkun Gao,&nbsp;Chuizheng Kong,&nbsp;Erlei Zhang,&nbsp;Mingzhu Liu,&nbsp;Qing Yu,&nbsp;Dengfeng Yang,&nbsp;Gaoxue Wang,&nbsp;Tianqiang Liu,&nbsp;Erlong Wang","doi":"10.1111/jfd.70217","DOIUrl":"10.1111/jfd.70217","url":null,"abstract":"<div>\u0000 \u0000 <p>Fas-associated death domain protein (FADD) was initially identified for its involvement in apoptosis signal transduction, while subsequent research has revealed its additional functions in proliferation, cell cycle regulation, inflammation, and innate immunity. However, current research on <i>FADD</i> predominantly focuses on mammals, with only limited studies conducted on fish. In this study, we cloned <i>FADD</i> from Nile tilapia (<i>Oreochromis niloticus</i>) and analysed its sequence characteristics. Subsequently, qPCR was used to detect the gene expression of <i>FADD</i> in healthy tissues and its changes in <i>Streptococcus agalactiae</i> infected tissues. After obtaining FADD through prokaryotic expression, its ability to bind to <i>S. agalactiae</i> was assessed using ELISA. Finally, the growth of <i>S. agalactiae</i> was assessed by adding FADD to the bacterial culture medium. The results indicate that the coding sequence of <i>FADD</i> spans 585 bp, encoding 194 amino acids. Predicted to be an intracellular protein, FADD exhibits high hydrophilicity and lacks transmembrane regions, with a structure predominantly composed of α-helices. <i>FADD</i> is widely expressed, with the highest levels found in the gill. Notably, the expression of <i>FADD</i> in peripheral blood, spleen, head kidney, and brain tissues changed significantly with the invasion of <i>S. agalactiae</i>. Furthermore, ELISA and absorbance assays confirmed that FADD binds to <i>S. agalactiae</i> and inhibits its growth, indicating the participation in tilapia resistance against <i>S. agalactiae</i> infection.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148031299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Two-Step PCR Workflow Reveals Predominance of Flavobacterium covae in Ornamental Fish With Clinical Signs of Columnaris Disease","authors":"Pedro Henrique Magalhães Cardoso,&nbsp;Emy Yano,&nbsp;Simone de Carvalho Balian,&nbsp;André Pegoraro Poor,&nbsp;Kawany Miyazaki Araujo,&nbsp;Marianna Vaz Rodrigues,&nbsp;Andrea Micke Moreno","doi":"10.1111/jfd.70228","DOIUrl":"10.1111/jfd.70228","url":null,"abstract":"<p>Columnaris is an important bacterial disease of freshwater fish and is increasingly recognised as being caused by a species complex historically referred to as <i>Flavobacterium columnare</i>. A two-step molecular workflow was applied to ornamental fish with clinical signs of columnaris disease from a multispecies commercial distributor operating a shared recirculating system in São Paulo, Brazil. Skin and fin lesion scrapings were Gram stained, and lesion-derived tissue DNA was screened by ISR-PCR for the columnaris disease complex. ISR-PCR yielded the expected amplicon in 61/123 samples (49.6%) from 28 ornamental fish species. All ISR-PCR-positive samples were then analysed by multiplex PCR for species assignment. Group-specific amplicons were obtained from 29/61 samples (47.5%): <i>Flavobacterium covae</i> in 27/61 (44.3%) and <i>F. davisii</i> in 2/61 (3.3%); no GG1 or GG4 amplicons were detected. The remaining 32/61 samples (52.5%) were not typeable by multiplex PCR. These findings provide baseline species-level data and support combined molecular surveillance in multispecies ornamental fish systems.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfd.70228","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148338726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gut Microbiota Dysbiosis Drives Lethal Bacterial Enteritis in Sturgeons: Insights From Ex Vivo Cultivation and Metagenomic Investigations","authors":"Dike Peng,&nbsp;Jiachen Zhou,&nbsp;Mengting Xiong,&nbsp;Yining Chen,&nbsp;Ye Zhang,&nbsp;Yacheng Hu,&nbsp;Yuanjin Yang,&nbsp;Jianan Xu,&nbsp;Yueping Zheng,&nbsp;Dan Xu","doi":"10.1111/jfd.70218","DOIUrl":"10.1111/jfd.70218","url":null,"abstract":"<div>\u0000 \u0000 <p>The Chinese sturgeon (<i>Acipenser sinensis</i>) and Yangtze sturgeon (<i>A. dabryanus</i>) are critically endangered flagship species. To investigate the intestinal microbial changes associated with bacterial enteritis in captive populations, we integrated bacterial isolation with metagenomic sequencing to characterize both healthy and maladjusted gut microbiomes. Healthy sturgeons exhibited a stable microbiota dominated by the beneficial <i>Cetobacterium</i>. In contrast, enteritis was consistently associated with severe dysbiosis, characterized by the depletion of these commensals and the massive expansion of opportunistic pathogens, notably <i>Aeromonas</i> and <i>Citrobacter</i>. Culture-based analyses identified <i>A. veronii</i>, <i>C. freundii</i> and <i>Plesiomonas shigelloides</i> as the dominant cultivable bacteria from diseased individuals; these isolates harboured diverse virulence traits and were multidrug-resistant. Crucially, both sturgeon species showed highly similar microbial responses and pathogenic profiles during enteritis. These findings indicate that sturgeon enteritis is closely correlated with a dysbiosis-driven syndrome. Establishing the healthy baseline provides a critical theoretical foundation for screening autochthonous probiotics and developing targeted pathogen control strategies. Furthermore, the striking cross-species commonality validates the Yangtze sturgeon as a viable surrogate model for advancing disease management and conservation in the difficult-to-breed Chinese sturgeon.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148176039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-of-Day-Dependent Host Defence Against Edwardsiella Infection in Medaka (Oryzias latipes)","authors":"Takahiko Hata,&nbsp;Miyu Hirayoshi,&nbsp;Hiyori Iwai,&nbsp;Yuiko Kuroyanagi,&nbsp;Minato Funakura,&nbsp;Jun-ichi Hikima,&nbsp;Tomoya Kono","doi":"10.1111/jfd.70226","DOIUrl":"10.1111/jfd.70226","url":null,"abstract":"<div>\u0000 \u0000 <p>Circadian rhythms regulate immune function in vertebrates; however, their contribution to infection outcomes in teleost fish remains unclear. Here, we examined whether infection timing influences host defence against <i>Edwardsiella piscicida</i> in Japanese medaka (<i>Oryzias latipes</i>). Fish were challenged by immersion with <i>E. piscicida</i> at ZT2 or ZT14 under a 12 h:12 h light–dark cycle, and survival was monitored for 16 days. To evaluate early immune responses, the expression of Toll-like receptors (TLRs) and pro-inflammatory cytokines in head kidney was analysed 6 h after infection by quantitative real-time PCR. Mortality began on day 3 post-infection, and survival differed significantly based on infection time: fish infected at ZT2 showed 75% survival, whereas those infected at ZT14 exhibited 25% survival. Expression levels of <i>tlr1</i>, <i>tlr5m</i>, <i>tlr21</i>, <i>il1b</i> and <i>tnfa</i> were significantly higher in fish infected at ZT2 than in those infected at ZT14, while <i>tlr9</i> showed a similar, but non-significant trend. These results indicate that early induction of pathogen recognition receptors and inflammatory cytokines in medaka differs according to the time of infection and is associated with different outcomes in host survival. Our findings suggest that time-of-day-dependent factors are important determinants of <i>E. piscicida</i> infection outcomes in teleost fish.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 11","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148301828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Protective Efficacy of Formalin-Killed and Auxotrophic-Live Vibrio anguillarum Against Homologous and Heterologous Strains in Rainbow Trout (Oncorhynchus mykiss).","authors":"Kyung Min Lee, Jong Min Lee, Ki Hong Kim","doi":"10.1111/jfd.70210","DOIUrl":"10.1111/jfd.70210","url":null,"abstract":"<p><p>Vibrio anguillarum infection poses a significant threat to freshwater and marine aquaculture. Although whole-cell killed and live attenuated vaccines are used to control vibriosis, their comparative efficacy against homologous and heterologous V. anguillarum strains remains limited. Here, we compared the protective efficacy and antibody responses of a formalin-killed V. anguillarum (FKC) and an alanine racemase gene knockout auxotrophic-live V. anguillarum (Δalr1Δalr2 V. anguillarum, LAV), both derived from the V. anguillarum JJ strain, in rainbow trout against homologous (JJ strain) and heterologous (V. anguillarum 90-11-287) strains. The LAV conferred superior protection compared to the FKC against both strains under high-dose challenge conditions. Despite this, ELISA antibody levels were comparable between vaccine groups and did not correlate with protective outcomes. No agglutination activity against the JJ strain was detected in vaccinated fish or rabbit antisera, suggesting limited assay sensitivity rather than absence of antibody binding. Analysis of the O-antigen biosynthesis-related genes revealed no genetic differences between strains; however, the JJ strain exhibited a shorter O-antigen, which may contribute to the reduced agglutination of the JJ strain. In conclusion, our results underscore the need for a comprehensive evaluation of vaccine performance, extending beyond antibody quantification, when developing effective vaccination strategies for aquaculture.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70210"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13532589/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147930380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}