Fish & shellfish immunology最新文献

{"title":"Surface-displayed MCP-3 vaccine in Bacillus subtilis elicits protective immune responses against LMBV infection in largemouth bass.","authors":"Ruiqi Lin, Zhihao Jiang, Qianqian Zhang, Shun Li, Xueying Qin, Xinyou Wang, Gaofeng Cheng, Zhen Xu, Weiguang Kong","doi":"10.1016/j.fsi.2026.111126","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111126","url":null,"abstract":"<p><p>Largemouth bass virus (LMBV) is a major pathogen threatening the aquaculture of largemouth bass, causing significant economic losses. Oral vaccination offers a practical and efficient strategy for disease prevention in farmed fish. In this study, a fusion CotC-MCP-3 gene was introduced into Bacillus subtilis 168 (Bs168) to enable surface display of the MCP-3 protein on bacterial spores through the anchoring protein CotC, thereby generating a candidate oral vaccine. At 28 days post-vaccination (dpv), qPCR analysis revealed pronounced upregulation of associated innate and adaptive immunity genes in the gut and head kidney of largemouth bass immunized with the MCP-3 vaccine. Vaccination markedly increased the abundance of IgM⁺ B cells in both the gut and head kidney, as well as total IgM levels in serum and gut mucus. Concomitantly, LMBV-specific IgM titers and neutralizing activities in both serum and gut mucus were significantly enhanced. Following the experimental LMBV challenge, fish in the MCP-3 vaccine group achieved a relative percent survival (RPS) of 68.7%, accompanied by substantially lower viral loads in the head kidney, gut, and spleen, as well as notably attenuated histopathological lesions compared with the other groups. The Bs168-based MCP-3 oral vaccine provides strong protection against LMBV infection in largemouth bass, as demonstrated by these results, highlighting its potential as a promising strategy for managing viral diseases in aquaculture.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111126"},"PeriodicalIF":3.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145984971","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":"The E3 ligase RNF5 facilitates viral replication by suppressing innate immune responses in grouper","authors":"Yanqi Zhao ,&nbsp;Xiaohui Zheng ,&nbsp;Siting Wu ,&nbsp;Minyao Bi ,&nbsp;Jiaming Hu ,&nbsp;Shaojie Liu ,&nbsp;Jingguang Wei ,&nbsp;Qiwei Qin","doi":"10.1016/j.fsi.2026.111123","DOIUrl":"10.1016/j.fsi.2026.111123","url":null,"abstract":"<div><div>Singapore grouper iridovirus (SGIV) and red-spotted grouper nervous necrosis virus (RGNNV) are major pathogens that cause high mortality and substantial economic losses in grouper aquaculture. The role of ring finger protein 5 (RNF5), an E3 ubiquitin ligase, in the antiviral innate immunity of teleosts remains poorly understood. In this study, a homolog of the RNF5 gene was identified and functionally characterized from <em>Epinephelus coioides</em>, which was designated EcRNF5. The open reading frame (ORF) of EcRNF5 is 645 nucleotides in length, encoding a 214-amino acid protein that contains a characteristic RING domain. Phylogenetic analysis revealed that EcRNF5 shares the closest evolutionary relationship with its ortholog in <em>Epinephelus fuscoguttatus</em>. EcRNF5 was ubiquitously expressed in all examined tissues. Furthermore, its transcription level was significantly upregulated in grouper spleen (GS) cells following challenge with SGIV or RGNNV. Overexpression of EcRNF5 enhanced SGIV and RGNNV replication in vitro. Concurrently, it suppressed the expression of interferon-related genes and pro-inflammatory cytokines. The promoter activities of interferon 3 (IFN3), interferon-stimulated response element (ISRE), and nuclear factor kappa B (NF-κB) were also inhibited. In addition, EcRNF5 attenuated IFN3 promoter activation induced by the key signaling molecules: EcSTING, EcTBK1, EcIRF3, and EcIRF7. Co-immunoprecipitation (Co-IP) assays confirmed physical interactions between EcRNF5 and these four innate immune signaling molecules. Collectively, these findings provide novel insights into the functional role of RNF5 in fish-virus interactions and shed light on the molecular mechanisms underlying SGIV and RGNNV pathogenicity in grouper.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111123"},"PeriodicalIF":3.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974592","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":"Yorkie antagonizes innate antiviral immunity through regulating the IRF and Dorsal mediated antiviral pathways in Litopenaeus vannamei","authors":"Guoqing Dai ,&nbsp;Wei Xiao ,&nbsp;Huiling Xing ,&nbsp;Lili Shi","doi":"10.1016/j.fsi.2026.111121","DOIUrl":"10.1016/j.fsi.2026.111121","url":null,"abstract":"<div><h3>Yorkie</h3><div>(<em>Yki</em>), a key effector of the Hippo signaling pathway, plays important roles in the regulation of cell proliferation and immune responses. In this study, two splice variants of the Yorkie gene (designated as <em>LvYki-long</em> and <em>LvYki-short</em>, respectively) were identified from <em>Litopenaeus vannamei.</em> The open reading frame (ORF) of <em>LvYki-long is</em> 1650 bp that encodes a putative protein of 549 amino acids. Compared with the amino acid sequence of LvYki-long, the amino acid sequence of LvYki-short is reduced by 78 amino acids (positions 416–493). Both <em>LvYki-long</em> and <em>LvYki-short</em> were universally expressed in all tested tissues. Following WSSV and DIV1 infection, their expression was significantly up-regulated in hemocytes and hepatopancreas but down-regulated in gills. The dsRNA-mediated knockdown of <em>LvYki</em> substantially enhanced the shrimp survival rate and reduced viral loads after WSSV and DIV1 infection. Besides, silencing of <em>LvYki</em> led to the down-regulation of <em>Cactus</em>, the up-regulation of <em>Dorsal,</em> as well as several AMPs (<em>ALF1</em>, <em>ALF2, ALF4,</em> and <em>SWD3</em>). Furthermore, silencing of <em>LvYki</em> also resulted in increased expression levels of Vago-JAK/STAT pathway components (<em>Vago4, Vago5,</em> and <em>STAT</em>)<em>,</em> and the Co-IP results showed that LvYki could interact with LvIRF. The dual luciferase assay verified that LvYki significantly inhibited the activation of the Vago4 promoter by LvIRF. These results indicated that <em>LvYki</em> might antagonize the innate antiviral immunity through regulating the IRF and Dorsal-mediated antiviral pathways.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111121"},"PeriodicalIF":3.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974593","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":"Recombinant phage-display monoclonal antibody against starry flounder (Platichthys stellatus) IgM enables quantitative ELISA for vaccine-induced humoral responses","authors":"Min-Young Sohn ,&nbsp;Jun-ichi Hikima ,&nbsp;Gyoungsik Kang ,&nbsp;Kyung-Ho Kim ,&nbsp;Ha-Jeong Son ,&nbsp;Chan-Il Park","doi":"10.1016/j.fsi.2026.111127","DOIUrl":"10.1016/j.fsi.2026.111127","url":null,"abstract":"<div><div>Species-matched serological reagents are scarce for many aquaculture species, limiting quantitative assessment of vaccine responses. Here, we developed and validated monoclonal antibodies (MAbs) specific to starry flounder (<em>Platichthys stellatus</em>) immunoglobulin M (IgM) using a recombinant phage-display approach. IgM purified from immune serum was used as the antigen for bio-panning, yielding multiple IgM-reactive scFv candidates, all of which recognized the IgM heavy chain by Western blot analysis. A lead clone (1T1A11) was reformatted as an scFv-Fc minibody, expressed in mammalian cells, purified by Protein A affinity chromatography, and verified as a single band of the expected molecular size. The 1T1A11 minibody specifically immunoprecipitated IgM from both purified preparations and serum, confirming its functional specificity. Using this monoclonal antibody, we established an optimized indirect ELISA to quantitatively monitor humoral immune responses following <em>Streptococcus parauberis</em> formalin-killed cell vaccination. The assay revealed clear dose- and time-dependent increases in serum IgM levels, which were further quantified using a purified starry flounder IgM standard curve. Collectively, these results establish 1T1A11 as a specific and scalable reagent that enables standardized, quantitative serological analysis for vaccine evaluation and diagnostic applications in flatfish aquaculture.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111127"},"PeriodicalIF":3.9,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974559","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":"Genomic selection accelerates genetic improvement of tolerance to visceral nodular disease in the half-smooth tongue sole (Cynoglossus semilaevis)","authors":"Mengyang Chang ,&nbsp;Kunpeng Shi ,&nbsp;Jibin Shen ,&nbsp;Yu Yang ,&nbsp;Yishuai Li ,&nbsp;Jiayu Cheng ,&nbsp;Xiangming Cheng ,&nbsp;Yingming Yang ,&nbsp;Zhongkai Cui ,&nbsp;Songlin Chen ,&nbsp;Zhenxia Sha","doi":"10.1016/j.fsi.2026.111115","DOIUrl":"10.1016/j.fsi.2026.111115","url":null,"abstract":"<div><div>The half-smooth tongue sole (<em>Cynoglossus semilaevis</em>) is an economically important marine fish in China, but its vulnerability to visceral nodular disease (VND) caused by <em>Mycobacterium marinum</em> poses a significant threat to aquaculture. Based on traditional breeding methods, it is slowly to improve disease tolerance and then may lead to inbreeding depression. This study aimed to accelerate the development of VND-tolerant strains of <em>C. semilaevis</em> through genomic selection (GS). In this study, individuals from both reference and candidate populations were genotyped, and more than 7 million high-quality SNPs were identified by whole genome sequencing (WGS). Heritability estimates for VND tolerance, based on binary survival status and survival time, were 0.37 and 0.39, respectively, indicating moderate genetic control. To improve breeding efficiency, six GS models (Bayes A, Bayes B, BayesCpi, ssGBLUP, GBLUP, and rrBLUP) were evaluated, of which GBLUP showed the highest prediction accuracy (0.4925 for binary state and 0.5477 for survival time). Furthermore,the effect of SNP density on genomic prediction accuracy was investigated and it was found that 40K SNPs, selected via GWAS, provided the most reliable predictions. Through the GBLUP model with 40K SNPs, genomic estimated breeding values (GEBVs) were estimated for the candidate population and top 20 % was selected for breeding. Progeny from these selected individuals showed significantly higher survival rates in response to VND challenge, with 19.7 % increase compared to the control group, and these results confirmed the effectiveness of GS in enhancing disease tolerance. This study provides a promising approach to developing VND-tolerant <em>C. semilaevis</em>, which could significantly improve the sustainability of aquaculture.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111115"},"PeriodicalIF":3.9,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923760","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":"The Atlantic salmon tongue mucosa functions as an active mucosal immune site capable of responding to a pathogen.","authors":"Carlo C Lazado, Elisabeth Ytteborg, Hanne Brenne, Muhammad Salman Malik, Malene Soleng, Erik Burgerhout, Aleksei Krasnov, Marianne Iversen","doi":"10.1016/j.fsi.2026.111120","DOIUrl":"10.1016/j.fsi.2026.111120","url":null,"abstract":"<p><p>The tongue of teleost fish is a mucosal organ whose role in immunity remains largely understudied. Here, we performed transcriptomic analyses of the Atlantic salmon (Salmo salar) smolt tongue to investigate its baseline gene expression profile and its immune response to a bacterial challenge with Yersinia ruckeri. In the unstimulated state, transcriptomic profiling revealed that the tongue is a highly metabolically active organ with enrichment of genes involved in cytoskeletal organisation, transport, and metabolism. Gene ontology (GO) analysis identified terms associated with immune system processes indicating that the tongue maintains a state of immune readiness even in the absence of infection or pathogenic stimulation. The transcriptional body map further revealed that the tongue shares gene expression features at the naïve state with both muscular and mucosal tissues including genes related to immunity. Following bacterial exposure both ex vivo and in vivo, an immune response was observed and was characterised by the upregulation of cytokines, chemokines, and antimicrobial effectors. GO and KEGG pathway enrichment analyses identified activation of immune- and metabolism-related pathways, including immune signalling, oxidative phosphorylation, lysosome, and phagosome pathways, thus reflecting the high energetic demand of the immune response to the bacterial pathogen. These findings collectively reveal that a transient bacterial challenge elicits a metabolically demanding immune response in the salmon tongue driven by coordinated regulation of immune signalling and cellular metabolic pathways. This study demonstrates that the Atlantic salmon tongue is an active component of the mucosal immune system and provides novel insights into the intersection of metabolism and immunity in fish mucosal organs, particularly in response to a transient bacterial challenge.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111120"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145951781","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":"The identification of SiMyD88 confirms the presence of a functional TLR-MyD88-IRAK signaling axis in the sea urchin Strongylocentrotus intermedius","authors":"Haikun Zhang ,&nbsp;Xuewei Qu ,&nbsp;Xuan Ding ,&nbsp;Guoshun Ren ,&nbsp;Vengatesen Thiyagarajan ,&nbsp;Xiaolong Chu ,&nbsp;Fengchen Liu ,&nbsp;Jie Cui ,&nbsp;Yifan Qu ,&nbsp;Yaqiong Liu ,&nbsp;Yijing Han ,&nbsp;Baoyu Huang ,&nbsp;Xiaotong Wang","doi":"10.1016/j.fsi.2026.111118","DOIUrl":"10.1016/j.fsi.2026.111118","url":null,"abstract":"<div><div>Myeloid differentiation primary response gene 88 (MyD88), a central adaptor protein in the Toll-like receptor (TLR) signaling pathway, plays a key role in the innate immune responses of animals. However, the signal transduction pathway mediated by MyD88 and the associated immune functions of the protein in echinoderms are not well characterized. In this study, a novel <em>MyD88</em> gene (<em>SiMyD88</em>) was cloned from the sea urchin <em>Strongylocentrotus intermedius</em>. Bioinformatics analysis revealed that <em>SiMyD88</em> contains a 1,101-bp-long open reading frame encoding a polypeptide of 366 amino acids. The N-terminal region of SiMyD88 harbors a death domain followed by a Toll/interleukin-1 receptor (TIR) domain, both of which were found through multiple sequence alignment to be highly conserved across species. Phylogenetic analysis revealed that SiMyD88 clustered closely with MyD88 proteins from other echinoderm species, suggesting a high degree of evolutionary conservation within this protein family. RT-qPCR analysis showed that the esophagus expressed the highest level of <em>SiMyD88</em> transcripts, whereas subcellular localization studies indicated that the protein was predominantly localized in the cytoplasm. The induction of <em>SiMyD88</em> mRNA expression by lipopolysaccharide and poly(I:C) suggests that this gene plays a critical role in mediating the immune response of sea urchins to bacterial and viral stimuli. More importantly, co-immunoprecipitation experiments revealed that SiMyD88 interacted with multiple TLR proteins in sea urchins and was capable of self-association. Furthermore, SiMyD88 interacted directly with interleukin-1 receptor-associated kinase (IRAK). Dual-luciferase reporter gene assays showed that <em>SiMyD88</em> overexpression in HEK293T cells significantly activated the transcriptional activities of activator protein-1, interleukin-6, and nuclear factor-kappa B (NF-κB) reporter genes, indicating its potential involvement in multiple signaling pathways. Collectively, these results suggest that SiMyD88 responds to pathogen-associated molecular patterns in TLR–MyD88–IRAK immune signaling, and potentially regulates downstream effector proteins such as the transcription factor NF-κB. These findings contribute to our understanding of innate immunity in echinoderms and provide a foundation for future research on strategies for breeding disease-resistant sea urchins.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111118"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923763","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":"Combined effects of temperature and metals on immunity of juveniles of European oyster Ostrea edulis","authors":"Halina Falfushynska ,&nbsp;Dominique Noetzel ,&nbsp;Bernd Sures ,&nbsp;Milen Nachev ,&nbsp;Bernadette Pogoda ,&nbsp;Bérenger Colsoul ,&nbsp;Inna M. Sokolova","doi":"10.1016/j.fsi.2026.111119","DOIUrl":"10.1016/j.fsi.2026.111119","url":null,"abstract":"<div><div>The European flat oyster (<em>Ostrea edulis</em>) is a foundational ecosystem engineer that has suffered widespread population declines due to overfishing, habitat degradation, and disease. Effective restoration requires understanding how environmental stressors impact juvenile oysters, a critical life stage for survival and recruitment. While trace metals such as zinc (Zn) and copper (Cu) are essential micronutrients, elevated concentrations can disrupt cellular physiology and immune function, particularly under temperature fluctuations associated with climate change. In this study, we investigated the combined effects of dissolved Zn (100 and 1000 μg L⁻¹) and Cu (10 and 100 μg L⁻¹) at three temperatures (5 °C, 15 °C, 22 °C) on immune defenses in juvenile <em>O. edulis</em>. Baseline tissue concentrations in controls were 73.0 ± 9.5 μg g⁻¹ Cu and 1240.5 ± 113.7 μg g⁻¹ Zn and were unaffected by temperature. Low metal exposures did not alter tissue concentrations, whereas high exposures induced temperature-dependent accumulation, peaking at 22 °C (CuH: 381.9 ± 78.6 μg g⁻¹; ZnH: 4573.6 ± 603.8 μg g⁻¹). Temperature strongly modulated cellular immunity: hemocyte abundance was highest at 15 °C, phagocytosis and acid phosphatase activity increased at 22 °C, while lipid peroxidation levels were elevated at 5 °C and 22 °C, indicating stress-induced responses at thermal extremes. Zn stimulated acid phosphatase but suppressed phenoloxidase activity, whereas Cu increased hemocyte mortality and modestly stimulated phenoloxidase. Lysozyme activity was elevated at cold exposure (5 °C), suggesting enhanced antibacterial defenses. Multivariate PLS-DA analyses revealed clearer separation of immune profiles by temperature than by metal exposure. These results demonstrate that temperature is the dominant factor shaping immune competence in juvenile <em>O. edulis</em>, while metal contamination at environmentally realistic levels exerts only minor effects, with implications for restoration and management under climate change.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111119"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145951754","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":"Protective efficacy of the optimized GluB-MTAP fusion subunit vaccine against Nocardia seriolae infection in largemouth bass (Micropterus salmoides)","authors":"Kuiquan Pan ,&nbsp;Xianzhe Peng ,&nbsp;Yuhang Li ,&nbsp;Tian Bai ,&nbsp;Zhongyu Zhang ,&nbsp;Xiaozhou Qi ,&nbsp;Tao Liu ,&nbsp;Gaoxue Wang ,&nbsp;Fei Ling","doi":"10.1016/j.fsi.2026.111117","DOIUrl":"10.1016/j.fsi.2026.111117","url":null,"abstract":"<div><div><em>Nocardia seriolae</em> is the predominant causative agent of piscine nocardiosis, exhibiting broad piscine host specificity along with prolonged latency periods and high mortality rates, thereby posing a severe threat to global fish health. However, reliably effective control measures remain limited. Subunit vaccines, derived from virulence factors or immunodominant proteins of the pathogen, are widely acknowledged as one of the most secure and potent strategies for mitigating disease outbreaks. Here we focused on five T7SS gene cluster proteins (MTAP, HP05, HP23, HP24, and VST) and the dominant <em>N. seriolae</em> secretory protein (GluB) as subunit vaccine candidates through whole-genome sequencing and HPLC-MS analysis, identifying GluB and MTAP as superior antigens through efficacy-based screening assessing immunogenicity, serum antibody titers, and protective efficacy. To further enhance the protective efficacy, we engineered a novel fusion antigen composed of GluB and MTAP. In <em>Micropterus salmoides</em>, immunization with the GluB-MTAP fusion antigen elicited robust defensive responses at 28 days post-immunization, characterized by enhanced antioxidant capacity and amplified inflammatory and humoral immunity. The fusion vaccine conferred significant protection against <em>N. seriolae</em> challenge with a relative percentage survival (RPS_21d) of 70 %, achieving 72.3 % absolute survival compared to 8 % in controls, which represented absolute survival improvements of 6.3 % over GluB-monovalent (66 %) and 18.3 % over MTAP-monovalent immunization (54 %). Collectively, the GluB-MTAP subunit vaccine demonstrates substantial efficacy against nocardiosis in <em>M. salmoides</em>, providing a mechanistic platform for investigating <em>Nocardia</em>-host interplay. This study further establishes a rational framework for anti-<em>Nocardia seriolae</em> vaccine development and advances sustainable aquaculture disease control strategies.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111117"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923761","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":"Activation of the Nrf2-Keap1 pathway is associated with NAC-mediated alleviation of nitrite-induced oxidative and endoplasmic reticulum stress and apoptosis in Marsupenaeus japonicus","authors":"Yexin Lei,&nbsp;Rui Xu,&nbsp;Jinlong Zhan,&nbsp;Jianyong Liu","doi":"10.1016/j.fsi.2026.111114","DOIUrl":"10.1016/j.fsi.2026.111114","url":null,"abstract":"<div><div>Nitrite accumulation poses a serious threat to aquatic animals in intensive aquaculture systems. Although the antioxidant role of the Nrf2-Keap1 pathway is well established, its regulatory mechanisms under nitrite stress in crustaceans remain poorly understood. This investigation focused on the protective impact of N-acetylcysteine (NAC) on <em>Marsupenaeus japonicus</em> exposed to nitrite toxicity. Shrimp were injected with NAC or PBS and then exposed to 100 mg/L of nitrite nitrogen for 72 h. The findings revealed that pretreatment with NAC markedly reduced tissue damage in both the hepatopancreas and gills, in comparison to the PBS control group. Additionally, the NAC-treated <em>M. japonicus</em> exhibited upregulated mRNA levels of <em>Nrf2</em> and its associated antioxidant genes including <em>NQO1</em>, <em>HO-1</em>, <em>CAT</em>, <em>GPx</em>, <em>GST</em>, and <em>SOD</em>, while <em>Keap1</em> expression was notably suppressed. Additionally, the NAC group downregulated endoplasmic reticulum stress (ERS)-related genes (<em>PERK</em>, <em>eIF2α</em>, <em>ATF4</em>, <em>GRP78</em>, <em>CHOP</em>, <em>IRE1</em>, <em>XBP1</em>, <em>ATF6</em>) and apoptosis-related genes (<em>Caspase-3</em>, <em>Caspase-9</em>, <em>p53</em>, <em>Bax</em>, <em>Apaf-1</em>), while upregulating <em>Bcl-2</em>. Additionally, the NAC group improved total antioxidant capacity (T-AOC) and SOD activity, reduced malondialdehyde (MDA) content and Caspase-3 activity, and decreased the apoptosis rate in the hepatopancreas. The results indicate that NAC alleviates oxidative stress, ERS, and apoptosis triggered by nitrite in <em>M. japonicus</em>. This protective effect is associated with the activation of the Nrf2-Keap1 signaling pathway, suggesting its potential as a therapeutic strategy for nitrite toxicity in crustacean aquaculture.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"170 ","pages":"Article 111114"},"PeriodicalIF":3.9,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923758","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}