Fish & shellfish immunology最新文献

{"title":"Spotted knifejaw (Oplegnathus punctatus) TARBP2 negatively regulates type I IFN responses to promote RGNNV replication","authors":"Yijie Lin ,&nbsp;Weifu Mo ,&nbsp;Xinyu Liao ,&nbsp;Minyao Bi ,&nbsp;Siting Wu ,&nbsp;Qiwei Qin ,&nbsp;Jingguang Wei","doi":"10.1016/j.fsi.2025.110892","DOIUrl":"10.1016/j.fsi.2025.110892","url":null,"abstract":"<div><div>Trans-Activation-Responsive RNA-Binding Protein (TARBP), a dsRNA-binding protein family member, serves as a hub for regulating gene expression and influencing diverse biological processes. While current research primarily focuses on its cytoplasmic interactions with factors like Dicer, protein kinase RNA-activated (PKR), and PKR activator (PACT), its role in teleost antiviral immunity remains less explored. In this study, we cloned and characterized an ortholog of TARBP2 from spotted knifejaw (<em>Oplegnathus punctatus</em>), designated OpTARBP2. Its open reading frame (ORF) spans 1038 bp, encoding a 345-amino acid protein with a predicted molecular weight of 37.1 kDa. Sequence analysis revealed that OpTARBP2 possesses three conserved dsRNA-binding domains and shares 96.81 % sequence homology with giant grouper (<em>Epinephelus lanceolatus</em>) TARBP2. Expression profiling indicated widespread OpTARBP2 distribution across tissues, with highest levels in the liver and intestine. Fluorescence microscopy confirmed its cytoplasmic localization. Functionally, overexpression of OpTARBP2 in grouper spleen (GS) cells reduced the transcription of pro-inflammatory cytokines and interferon-related genes, and thereby promoting replication of the red-spotted grouper nervous necrosis virus (RGNNV). Furthermore, OpTARBP2 significantly inhibited <em>E. coioides</em> Melanoma differentiation-associated gene 5 (MDA5), Mitochondrial anti viral signaling protein (MAVS), and TANK-Binding Kinase 1 (TBK1)-induced luciferase activity driven by the Interferon-stimulated response elements (ISRE) and NF-κB promoters. Collectively, these results demonstrate that OpTARBP2 enhanced viral replication by negatively regulating type I interferon responses, laying a foundation for understanding the antiviral immune role of TARBP2 in teleosts.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110892"},"PeriodicalIF":3.9,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated metabolome-SNP-gut microbiome analysis deciphers the molecular basis of EHP resistance in Penaeus vannamei","authors":"Yang Du ,&nbsp;Xiangrong Tian ,&nbsp;Jiong Chen","doi":"10.1016/j.fsi.2025.110893","DOIUrl":"10.1016/j.fsi.2025.110893","url":null,"abstract":"<div><div><em>Enterocytozoon hepatopenaei</em> (EHP) has emerged as a highly virulent pathogen in shrimp aquaculture, yet the molecular determinants governing host resistance remain incompletely characterized. This study employed an integrated multi-omics strategy (metabolome, transcriptome, and microbiome) to elucidate the molecular basis of EHP resistance in <em>Penaeus vannamei</em>. Comparative metabolomic profiling of EHP-resistant (R4029) and susceptible (S4104) family lines identified 1614 metabolites, primarily organic acids (35.07 %) and lipids (21.56 %). Orthogonal partial least squares discriminant analysis (OPLS-DA) revealed significant intergroup metabolic differentiation (Q² &gt; 0.9), with 428 and 388 metabolites exhibiting differential abundance (variable importance in projection |VIP| &gt; 1, false discovery rate-adjusted <em>P &lt;</em> 0.05) identified in uninfected (S4104-D vs R4029-D) and infected (S4104-G vs R4029-G) states, respectively. Joint KEGG pathway enrichment analysis of transcriptomic and metabolomic datasets identified 661 commonly dysregulated genes (DEGs) and 205 differentially abundant metabolites (DEMs), with glycine/serine/threonine metabolism (ko00260) and cysteine/methionine metabolism (ko00270) emerging as pivotal pathways underpining resistance. Integrative multi-omics analysis using O2PLS modelling revealed robust correlations between 12 key DEGs and 15 DEMs, thereby prioritizing macrophage mannose receptor 1 (<em>MRC1</em>) and betaine-homocysteine S-methyltransferase (<em>BHMT</em>) as principal candidate genes. Single-nucleotide polymorphism (SNP) screening identified seven <em>BHMT</em> sequence variants, including three variants significantly associated with resistance (<em>BHMT</em>-8159 in intron 3; <em>BHMT</em>-12167 and <em>BHMT</em>-12710 in exonic regions), as well as fourteen <em>MRC1</em> variants, of which six showed significant associations (<em>P &lt;</em> 0.05), most notably the missense mutation <em>MRC1</em>-759 (A &gt; C) inducing a Thr253Pro substitution (full-length <em>MRC1</em> sequence) that alters protein secondary structure. Gut microbiome characterization demonstrated elevated α-diversity (<em>P &lt;</em> 0.05) and enhanced community stability in resistant shrimp, with selective enrichment of putatively beneficial taxa (<em>Photobacterium</em>, <em>Ralstonia</em>). Collectively, these findings suggest that EHP resistance is mediated by coordinated transcriptional and metabolic reprogramming, functionally consequential genetic polymorphisms, and stable microbial community dynamics, thereby establishing a multi-omics framework for the selective breeding of EHP-resistant shrimp.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110893"},"PeriodicalIF":3.9,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foreword to \"The 5^th conference of the international society of fish and shellfish immunology (5^th ISFSI) in Tainan, Taiwan (R.O.C.) (November 4^th - 8^th, 2025)\".","authors":"Han-Ching Wang","doi":"10.1016/j.fsi.2025.110891","DOIUrl":"10.1016/j.fsi.2025.110891","url":null,"abstract":"","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"110891"},"PeriodicalIF":3.9,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145124645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pufferfish insulin-like growth factor binding protein 5 regulates host antimicrobial immune responses by modulating cytokines expression","authors":"Linchao Wang ,&nbsp;Tong Chen ,&nbsp;Wenjing Du ,&nbsp;Yongqi Jin ,&nbsp;Faling Zhang ,&nbsp;Guosong Zhang ,&nbsp;Fenfei Liang","doi":"10.1016/j.fsi.2025.110890","DOIUrl":"10.1016/j.fsi.2025.110890","url":null,"abstract":"<div><div>Insulin-like growth factor binding protein 5 (IGFBP5) plays crucial roles in growth and development, but its immunological functions in teleosts remain poorly understood. This study characterized the molecular features and immune function of IGFBP5 (<em>ToIGFBP5</em>) in pufferfish <em>Takifugu obscurus</em>. Bioinformatic analysis revealed the ToIGFBP5 coding sequence spans 798 bp, encoding a 265-amino acid protein featuring a signal peptide, an IGF-binding domain, and a thyroglobulin type-1 domain, with predicted tertiary structure comprising seven α-helices and seven β-strands. Basal tissue expression profiling via RT-qPCR detected <em>ToIGFBP5</em> transcripts ubiquitously, with the highest abundance in liver, followed by head kidney, intestine, and gills. Following <em>Vibrio</em> challenge, <em>ToIGFBP5</em> exhibited rapid, significant upregulation in head kidney and liver tissues. To functionally dissect a predicted heparin-binding motif (HBM), recombinant plasmids expressing wild-type or HBM-deleted protein were constructed. Overexpression of pToIGFBP5-WT prior to bacterial challenge significantly amplified pro-inflammatory cytokines (<em>IL-1β</em>, <em>IL-8</em>, and <em>TNF-α</em>) expression in head kidney and liver at 12 hpi and significantly enhanced bacterial clearance compared to controls. Crucially, these immunomodulatory and antibacterial effects were markedly attenuated in fish overexpressing pToIGFBP5-ΔHBM. These results indicate that ToIGFBP5 acts as an immune mediator in <em>T. obscurus</em>, modulating innate immunity against pathogenic <em>Vibrio</em> species primarily through its HBM-dependent mechanism.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110890"},"PeriodicalIF":3.9,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis on antioxidant capacity, immunity and histopathological changes of largemouth bass (Micropterus salmoides) in response to mono- or co-infection with Aeromonas veronii and Nocardia seriolae","authors":"Gaofeng Cheng ,&nbsp;Nengbin Zhu ,&nbsp;Ruiping Xu ,&nbsp;Eakapol Wangkahart ,&nbsp;Lin Zhang ,&nbsp;Lihe Liu ,&nbsp;Rui Wang ,&nbsp;Zhen Xu ,&nbsp;Weiguang Kong ,&nbsp;Hongsen Xu","doi":"10.1016/j.fsi.2025.110886","DOIUrl":"10.1016/j.fsi.2025.110886","url":null,"abstract":"<div><div>Previous research has found that largemouth bass co-infected with <em>Aeromonas veronii</em> and <em>Nocardia seriolae</em> caused quicker and higher mortality than those infected by one single bacteria. Whereas, the pathogenic mechanism of co-infection with <em>A</em>. <em>veronii</em> and <em>N</em>. <em>seriolae</em> is still unclear. To explore this reason, the bacterial load in liver, spleen and head kidney, as well as the antioxidant capacity, non-specific immunity, histopathological changes and gene expression profiles of largemouth bass were both investigated and comparatively analyzed following mono- and co-infections. The results revealed that the total amount of <em>A. veronii</em> and <em>N. seriolae</em> in liver, spleen and head kidney of co-infected fish was significantly (<em>P</em> &lt; 0.05) higher than that of every single infected fish at 7^th and 14^th days post-infection (dpi). Meanwhile, the activities of SOD, GSH-Px, AKP and LZM were remarkably (<em>P</em> &lt; 0.05) decreased in infected fish, whereas the CAT and ACP capacities were increased. Moreover, the expression levels of immune-related genes in the spleen and head kidney increased initially and then decreased during 96 h after infection, whereas apoptosis-related genes showed a continuous rise. Especially, the mRNA profile of genes from co-infected fish was higher than that of each single infected fish at the time when the maximum expression appeared. In addition, the liver, spleen, head kidney and intestine of largemouth bass exhibited severe tissue lesions after infection. Particularly, the degree of damage in co-infected fish was more serious than that of each single infected fish. The results will advance our knowledge on the interaction between pathogenic bacteria and host immune system during mono- or co-infection with <em>A. veronii</em> and <em>N. seriolae</em>, and then help to develop management strategies to mitigate the impact of bacterial infection on largemouth bass production.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110886"},"PeriodicalIF":3.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to \"Mucosal barrier status in Atlantic salmon fed rapeseed oil and Schizochytrium oil partly or fully replacing fish oil through winter depression\" [Fish Shellfish Immunol. 149 (2024) 109549].","authors":"Sm Majharul Islam, Florence Perera Willora, Mette Sørensen, Golam Rbbani, Muhammad A B Siddik, Kyla Zatti, Shruti Gupta, Ian Carr, Ester Santigosa, Monica F Brinchmann, Kim D Thompson, Ioannis N Vatsos","doi":"10.1016/j.fsi.2025.110884","DOIUrl":"https://doi.org/10.1016/j.fsi.2025.110884","url":null,"abstract":"","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"110884"},"PeriodicalIF":3.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mucosal defences of salmonids in complex RAS environments","authors":"Carlo C. Lazado ,&nbsp;Juan Bosco Ara-Díaz ,&nbsp;Kevin T. Stiller","doi":"10.1016/j.fsi.2025.110889","DOIUrl":"10.1016/j.fsi.2025.110889","url":null,"abstract":"<div><div>Defences at mucosal sites play a critical role in forming robust primary barriers of fish. Because of their close contact with the aquatic environment, these mucosal immune structures and mechanisms are under constant pressure from environmental challenges, especially in intensive aquaculture systems. As recirculating aquaculture systems (RAS) become more widely adopted, there is increasing interest in understanding how these controlled, complex, land-based environments affect mucosal defences in cultured species, particularly salmonids. Modern intensive RAS are highly intricate systems characterised by minimal water exchange and extensive water treatment processes to maintain water quality that supports the biological requirements of fish. However, the unique and dynamic nature of RAS environments exposes fish to a suite of physical, chemical, and microbial pressures that directly affect mucosal surfaces, including skin, gills, gut and olfactory organ. This review consolidates current knowledge on the primary environmental variables monitored in RAS and evaluates their known and potential impacts on the mucosal defences in fish, focusing on salmonids. While the health impacts of these parameters are documented to some extent, the specific consequences for mucosal health are unclear. The majority of these studies have focused on mucosal defences in the gills, with limited understanding of other mucosal organs. Moreover, current knowledge is largely based on histological evaluations, making it challenging to draw functional conclusions about the immunological processes and mechanisms influenced by RAS-related environmental factors. Given the integral role of mucosal barriers in disease resistance and immunity, deepening our understanding of how the RAS environment influences these surfaces is crucial for optimising production practices. As direct interfaces with the environment, mucosal surfaces provide valuable insights into rearing conditions, making their interaction with the RAS environment essential to ensuring fish health and welfare in intensive aquaculture.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110889"},"PeriodicalIF":3.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional characterization of two CCL20 chemokines in black rockfish (Sebastes schlegelii): dual roles in immune cell recruitment and direct antimicrobial defense","authors":"Fengjun Lin ,&nbsp;Yiying Liu ,&nbsp;Chonghui Chen,&nbsp;Xiaoxu Zhang,&nbsp;Pei Zhang,&nbsp;Huijun Huo,&nbsp;Chao Li,&nbsp;Qiang Fu","doi":"10.1016/j.fsi.2025.110879","DOIUrl":"10.1016/j.fsi.2025.110879","url":null,"abstract":"<div><div>Chemokines are cytokines with chemotactic capacities that regulate immune cell migration under both inflammatory and homeostatic conditions. To date, reports about the role of CCL20 in the fish immune system have been limited. In this study, we identified two CCL20 homologs (CCL20a.1/2) from black rockfish (<em>Sebastes schlegelii</em>), investigating their expression profiles post-<em>Aeromonas salmonicida</em> infection, chemotactic properties, antimicrobial mechanisms, and immunoregulatory functions. Structural characterization revealed <em>Ss</em>CCL20a.1 possesses a 369-bp ORF encoding 122 amino acids, whereas <em>Ss</em>CCL20a.2 contains a 309-bp ORF encoding 102 amino acids. Phylogenetic analysis demonstrated the closest homology to honeycomb rockfish CCL20, supported by conserved syntenic patterns across vertebrates. Tissue distribution analysis showed constitutive expression of both genes across all nine tissues, with peak expression in gill (<em>Ss</em>CCL20a.1) and liver (<em>Ss</em>CCL20a.2), and minimal levels in brain and spleen, respectively. Following bacterial challenge, both genes displayed significant upregulation in liver, kidney, and gill at multiple timepoints. In <em>vitro</em> functional assays revealed potent chemotactic activity toward spleen leukocytes and peripheral blood leukocytes. Notably, <em>Ss</em>CCL20a.1/2 exhibited strong binding capacity to microbial ligands (LPS, PGN, LTA) and Poly (I:C), and broad-spectrum bacterial agglutination. Mechanistic studies indicated direct bactericidal effects mediated through membrane disruption, as evidenced by structural damage to pathogen membranes. This investigation highlights the dual functionality of teleost CCL20 in orchestrating immune cell recruitment and executing direct antimicrobial defense, providing novel insights for developing therapeutic strategies against aquaculture pathogens.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110879"},"PeriodicalIF":3.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SGIV and RGNNV regulate fish innate immune responses by mediating ubiquitinated modifications of proteasome and ribosomal proteins","authors":"Siting Wu ,&nbsp;Zheng Zhu ,&nbsp;Yijie Lin ,&nbsp;Qiongyue Xu ,&nbsp;Xiaoxia Lei ,&nbsp;Jingguang Wei ,&nbsp;Qiwei Qin","doi":"10.1016/j.fsi.2025.110887","DOIUrl":"10.1016/j.fsi.2025.110887","url":null,"abstract":"<div><div>Singapore grouper iridovirus (SGIV) and red-spotted grouper nervous necrosis virus (RGNNV) have been identified as the predominant DNA and RNA viral pathogens, respectively, affecting grouper populations. Protein ubiquitination, a crucial post-translational modification, plays pivotal regulatory roles in both host innate immune responses and viral replication processes. In the present study, we employed quantitative proteomics approaches to systematically identify and characterize alterations in ubiquitination-modified proteins in grouper spleen (<em>Epinephelus akaara</em>, GS) cells following SGIV and RGNNV infection. Proteomic analysis revealed that differentially expressed proteins were predominantly enriched in ribosome- and proteasome-related signaling pathways and associated biological processes. STRING analysis and correlation analysis revealed ubiquitin-40S ribosomal protein S27a (RPS27a) as a key regulatory molecule demonstrating significant interactions and functional correlations with proteins involved in ribosome biogenesis and proteasome-mediated degradation during both SGIV and RGNNV infection. Mechanistic investigations demonstrated that the replication processes of both SGIV and RGNNV are critically dependent on the host proteasome system, with viral regulation of the NF-κB signaling pathway being mediated through the ubiquitin-proteasome system (UPS). Functional validation through overexpression and RNA interference approaches demonstrated that grouper ub-RPS27a (Ecub-RPS27a) significantly inhibits viral replication while modulating innate immune responses in virus-infected GS cells. Collectively, these findings provide novel insights into the molecular mechanisms governing viral pathogenesis and host-pathogen interactions during SGIV and RGNNV infection.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110887"},"PeriodicalIF":3.9,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic effects of co-infection with Flavobacterium psychrophilum and Aeromonas salmonicida on mortality, pathophysiology, and immune responses in rainbow trout (Oncorhynchus mykiss)","authors":"Jing Wang ,&nbsp;Ran Zhao ,&nbsp;Yanan Wang ,&nbsp;Bingchen Guo ,&nbsp;Shaowu Li ,&nbsp;Di Wang","doi":"10.1016/j.fsi.2025.110881","DOIUrl":"10.1016/j.fsi.2025.110881","url":null,"abstract":"<div><div>Bacterial co-infections pose a significant threat to aquaculture, often leading to more severe outcomes compared than mono-infections. Understanding the underlying mechanisms is essential to preventing and controlling diseases. In this study, we investigated the effects of mono-infection and co-infection with <em>Flavobacterium psychrophilum</em> (Fp) and <em>Aeromonas salmonicida</em> (As) on rainbow trout (<em>Oncorhynchus mykiss</em>). Results indicated that the mortality rate in the co-infection group was significantly higher than that in the mono-infected groups, with more severe histopathological damage observed in the liver and muscle tissues. On day 7 post-infection, the antioxidant enzyme (SOD and CAT) activity in the liver of the co-infection group peaked and subsequently declined. Transcriptomic analysis revealed that Fp mono-infection primarily activated the Toll-like receptor signaling pathway, whereas As mono-infection activated the MAPK signaling pathway. In contrast, co-infection (Fp + As) showed significant enrichment of DEGs in the p53 pathway, suggesting a unique apoptotic response potentially contributing to host defense through the elimination of compromised cells. This study demonstrates that co-infection with <em>F. psychrophilum</em> and <em>A. salmonicida</em> synergistically exacerbates disease progression in rainbow trout. These findings provide novel insights into co-infection risks, elucidate key immunopathological pathways, and establish a scientific basis for developing targeted disease interventions in aquaculture.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"167 ","pages":"Article 110881"},"PeriodicalIF":3.9,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}