Fish & shellfish immunology最新文献

{"title":"TLR18 Mediates Antibacterial Immunity via MyD88-Dependent NF-κB and IRF Pathways in Turbot (Scophthalmus maximus).","authors":"Honghong Li, Zhongyi Wang, Yang Li, Chao Li, Ning Yang","doi":"10.1016/j.fsi.2026.111379","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111379","url":null,"abstract":"<p><p>Toll-like receptors (TLRs), as core pattern recognition receptors (PRRs), play pivotal roles in pathogen detection during innate immune defense and are critical for initiating immune responses. In this study, we investigated a novel member of the TLR1 subfamily, TLR18, in the economically significant species Scophthalmus maximus, aiming to elucidate its molecular mechanisms in antibacterial immunity and provide insights into innate immune regulation in fish. In our results, SmTLR18 (2652 bp) ‌encoded‌ an 883-amino-acid protein sharing high identity with Paralichthys olivaceus TLR14 (84.15%). SmTLR18 localizes to the cytoplasm and cell membrane and is ubiquitously expressed with the highest expression level in spleen and lowest expression level in ‌the‌ blood. In vitro, SmTLR18 was upregulated by PGN and LTA but downregulated by LPS. The extracellular domain of SmTLR18 bound all tested ligands and bacteria, exhibiting the highest affinity for Vibrio anguillarum, and immunohistochemical analysis revealed strong positive SmTLR18 signals within hyperplastic hemocytes. Molecular docking, co-localization, and co-immunoprecipitation assays revealed that SmTLR18 recruits MyD88 to activate downstream signaling. Transcriptomics following SmTLR18 overexpression suggested regulation of IRF, ZBTB, MYSM, STAT, and zf-C2H pathways, upregulating MyD88 and IL-1β while downregulating TNF-α. Conversely, knockdown increased TNF-α and downregulated MyD88 and IL-1β. Mechanistically, dual-luciferase assays demonstrated SmTLR18-mediated NF-κB activation. Results demonstrated SmTLR18 recognizes PAMPs, specifically Vibrio anguillarum, and recruits MyD88 to activate NF-κB and IRF pathways driving cytokine production. These findings underscore the critical role of SmTLR18 in turbot antibacterial immunity.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111379"},"PeriodicalIF":3.9,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147856111","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":"A ceRNA axis of lncRNA MSTRG.14394.1/miR-144-3p/NR1H3 responds to diverse bacterial PAMPs in teleost fish.","authors":"Yishuai Li, Mengyang Chang, Suxu Tan, Wenwen Wang, Kunpeng Shi, Shaoqing Zang, Yiming Hu, Qingyang Fu, Songlin Chen, Zhenxia Sha","doi":"10.1016/j.fsi.2026.111396","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111396","url":null,"abstract":"<p><p>Precise post-transcriptional regulation is essential for balancing antibacterial defense and inflammatory homeostasis in teleost innate immunity. Here, we identified a competing endogenous RNA (ceRNA) axis involving lncRNA MSTRG.14394.1, miR-144-3p, and the nuclear receptor NR1H3 in Cynoglossus semilaevis. miR-144-3p was markedly induced by bacterial pathogen-associated molecular patterns (PAMPs), including lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN), and promoted hepatocyte injury and pro-inflammatory cytokine mRNA expression. Mechanistically, miR-144-3p directly targeted NR1H3 mRNA, whereas MSTRG.14394.1 acted as a ceRNA to sequester miR-144-3p and partially restore NR1H3 mRNA expression. These interactions were supported by luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. In vivo experiments in Danio rerio further showed that modulation of this axis significantly affected host survival following Vibrio anguillarum infection. Collectively, these findings identify a ceRNA-mediated regulatory network that modulates inflammatory responses in teleost fish and provide potential molecular targets for improving disease resistance in aquaculture.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111396"},"PeriodicalIF":3.9,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147856132","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":"Intraperitoneal extracellular trap-derived proteins mediate the amplification of vaccine-induced immune responses in flounder (Paralichthys olivaceus).","authors":"Jiahui Zhang, Qian Li, Xiaoqian Tang, Chengxu Ha, Jing Xing, Xiuzhen Sheng, Wenbin Zhan, Heng Chi","doi":"10.1016/j.fsi.2026.111399","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111399","url":null,"abstract":"<p><p>Myeloid cells are capable of releasing web-like extracellular structures composed of DNA and granular proteins, known as extracellular traps (ETs), which function to eliminate invading pathogens and modulate immune responses. Intraperitoneal vaccine administration has been demonstrated to induce ETs, but their roles in vaccine-mediated immune responses remain largely unknown. In this study, we show that a protein subunit vaccine triggers the release of ETs in the peritoneal cavity of teleost fish. Pharmacological inhibition of ET formation by 4-aminobenzoic acid hydrazide (ABAH) or enzymatic degradation of ETs by DNase I significantly reduces CD4-1⁺ and CD4-2⁺ T cell proportions in immune organs, decreases IgM⁺ B cell frequency in peripheral blood, and lowers antigen-specific antibody titers. Proteomic profiling of ETs generated in vivo and in vitro reveals that ET-derived proteins are enriched in molecules involved in immune regulatory pathways associated with macrophage activation, antigen presentation, and T cell proliferation and differentiation. Collectively, our findings indicate that ET-derived proteins act as core molecular scaffolds to boost vaccine-induced adaptive immune responses, offering novel insight into the bridging mechanisms between innate and adaptive immunity.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111399"},"PeriodicalIF":3.9,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147856180","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 IRF2 and IRF2a in Japanese eel (Anguilla japonica) identifies dual pathways suppressing interferon responses.","authors":"Haijun Qin, Dongli Li, Gejie Zhao, Pin Nie, Wenshu Huang, Bei Huang","doi":"10.1016/j.fsi.2026.111393","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111393","url":null,"abstract":"<p><p>Interferon regulatory factor 2 (IRF2) is a transcription factor that critically modulates innate antiviral immunity through regulation of interferon (IFN). In this study, two IRF2 homologs, AjIRF2 and AjIRF2a, were identified and characterized from Japanese eel (Anguilla japonica). Sequence analysis revealed that both proteins harbor a highly conserved DNA-binding domain (DBD). Expression analysis demonstrated that AjIRF2 and AjIRF2a are ubiquitously expressed across tissues, with AjIRF2a exhibiting consistently higher basal expression, particularly in the kidney. Upon infection with Anguillid herpesvirus 1 (AngHV-1), as well as stimulation with poly I:C, both AjIRF2 and AjIRF2a were markedly upregulated. Functional analyses showed that AjIRF2/2a attenuate the induction of AjIFNs and interferon-stimulated genes triggered by AngHV-1 or poly I:C, thereby facilitating viral replication. Dual-luciferase reporter assays further demonstrated that AjIRF2/2a antagonize AjIRF1- and AjIRF11-mediated activation of the AjIFN promoter by competing for interferon-stimulated response element (ISRE) binding, which depends on four key residues (Arg82, Cys83, Asn86, and Ser87) located within the α3 helix of the DBD. Notably, DBD-deficient mutants of AjIRF2/2a retained the ability to suppress AjIFN promoter activity following poly I:C stimulation, indicating the involvement of ISRE-independent mechanisms. Further studies revealed AjIRF2/2a facilitate the ubiquitination-dependent degradation of AjSTAT1a, thereby dampening IFN signaling output. Taken together, these findings establish AjIRF2 and AjIRF2a as negative regulators of antiviral innate immunity in Japanese eel, acting through both direct transcriptional interference and post-translational modulation of key signaling components to constrain IFN responses.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111393"},"PeriodicalIF":3.9,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147835780","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 function of stearoyl-CoA desaturase in unsaturated fatty acid biosynthesis and cold tolerance in Haliotis discus hannai.","authors":"Jie Qi, Wentong Hao, Ming Li, Hailin Zhao, Shiqing Sun, Lixin Feng, Ning Kong, Lingling Wang, Linsheng Song","doi":"10.1016/j.fsi.2026.111388","DOIUrl":"https://doi.org/10.1016/j.fsi.2026.111388","url":null,"abstract":"<p><p>The Pacific abalone Haliotis discus hannai is a nutritionally and economically important mollusk species predominantly cultivated in northern China. In recent years, recurrent winter cold spells have severely impaired the survival and growth of abalone, thereby constraining the development of its aquaculture industry. Unsaturated fatty acids (UFAs) play a vital role in cold tolerance, with stearoyl-CoA desaturase (SCD) acting as the rate-limiting enzyme in de novo UFA synthesis. In the present study, both UFA level and SCD activity in the hepatopancreas of H. discus hannai were significantly elevated after low temperature exposure. An SCD homolog HdSCD1, containing a conserved FA_desaturase domain, was identified in H. discus hannai. HdSCD1 mRNA was predominantly expressed in the hepatopancreas of abalone and increased significantly after low temperature exposure (p < 0.001). Recombinant HdSCD1 protein can catalyze the conversion of saturated fatty acids (SFAs) to UFAs. Overexpression of HdSCD1 in HEK293T cells increased UFA content by 72%, whereas knockdown of HdSCD1 by RNA interference (RNAi) decreased UFA content by 32% in the abalone hepatopancreas. Under cold stress, HdSCD1 knockdown significantly suppressed UFA accumulation in the hepatopancreas and resulted in a 2.88-fold increase in abalone mortality compared to the EGFP group. Moreover, HdSCD1 knockdown impaired the antioxidant system in abalone, as evidenced by decreased superoxide dismutase (SOD) and catalase (CAT) activities (0.61- and 0.56-fold of the EGFP group, respectively), reduced total antioxidant capacity (T-AOC; 0.92-fold of the EGFP group) and elevated malondialdehyde (MDA) content (1.23-fold of the EGFP group). In addition, the mRNA expression levels of HdNRF2, HdSOD and HdCAT were significantly decreased, while that of HdKEAP1 was significantly increased. Concurrently, compared to the EGFP group, the mRNA expression levels of inflammation-related genes (HdTLR4, HdMyD88, HdTNF-α, HdNF-κB, HdIL-6 and HdIL-1β) and apoptosis-related genes (HdCaspase3, HdCaspase7 and HdBax) were significantly upregulated. These results demonstrated that HdSCD1 functions as a fatty acid desaturase involved in UFA biosynthesis and plays an essential role in cold tolerance in H. discus hannai.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111388"},"PeriodicalIF":3.9,"publicationDate":"2026-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147835755","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":"Identification and expression profile of serotonin receptors in the developmental stages and hemocytes of the Pacific oyster (Crassostrea gigas)","authors":"Minhui Xu ,&nbsp;Miren Dong ,&nbsp;Xiaolong Gao ,&nbsp;Wei Wu ,&nbsp;Lingling Wang ,&nbsp;Chunlin Wang","doi":"10.1016/j.fsi.2026.111148","DOIUrl":"10.1016/j.fsi.2026.111148","url":null,"abstract":"<div><div>Serotonin (5-hydroxytryptamine, 5-HT), a pleiotropic biogenic monoamine, modulates immune response through interactions with its distinct receptors (5-HTRs). In this study, thirteen 5-HTRs were identified in the Pacific oyster (<em>Crassostrea gigas</em>) to elucidate their functions in immune response to <em>Vibrio</em> stimulation. Except for the unique ligand-gated cation channels (<em>Cg</em>5-HTR3A-like), the other twelve 5-HTRs (Two <em>Cg</em>5-HTR, <em>Cg</em>5-HTR-like, <em>Cg</em>5-HTR1, <em>Cg</em>5-HTR1A-like, <em>Cg</em>5-HTR1B, <em>Cg</em>5-HTR1B-like, <em>Cg</em>5-HTR2A-like, <em>Cg</em>5-HTR2B, <em>Cg</em>5-HTR4, <em>Cg</em>5-HTR5, and <em>Cg</em>5-HTR6) all belong to G protein-coupled receptor (GPCR) superfamily. Among those twelve 5-HTRs, most are non-canonical members lacking complete seven-transmembrane (7TM) domains; only <em>Cg</em>5-HTR2B and <em>Cg</em>5-HTR6 retain the canonical GPCR architecture. Ten conserved motifs were identified in oyster 5-HTRs, with motif 2 being universal across all receptors and motif 10 unique to <em>Cg</em>5-HTR3A-like, indicating subtype-specific divergence. Molecular docking revealed significant differences in binding affinity and residue interaction among <em>Cg</em>5-HTRs, with <em>Cg</em>5-HTR6 exhibiting the highest binding affinity for 5-HT. Analysis across developmental stages revealed that <em>Cg</em>5-HTR1A-like transcripts were enriched in early gastrula, gastrula and trochophore, <em>Cg</em>5-HTR4, <em>Cg</em>5-HTR1B, and <em>Cg</em>5-HTR-like enriched specifically in the D-shape stage, while <em>Cg</em>5-HTR2B and <em>Cg</em>5-HTR1 transcripts enriched during the pediveliger, spat, and juvenile stages. Furthermore, <em>Cg</em>5-HTR-like and <em>Cg</em>5-HTR1 were primarily expressed in granulocytes, <em>Cg</em>5-HTR1A-like and <em>Cg</em>5-HTR2B in agranulocytes, and <em>Cg</em>5-HTR6 and <em>Cg</em>5-HTR1B in semi-granulocytes. Crucially, following secondary <em>Vibrio splendidus</em> stimulation, the expression levels of <em>Cg</em>5-HTR-like, <em>Cg</em>5-HTR1, <em>Cg</em>5-HTR1A-like, <em>Cg</em>5-HTR1B and <em>Cg</em>5-HTR2B mRNA in hemocytes upregulated significantly, indicating their potential role in immune priming. These findings suggested the potential mechanisms of 5-HTRs in regulating the immune response of hemocytes in <em>C. gigas</em>, which offered insights into the evolutionary conservation and immunoregulation divergence of these receptors in invertebrates.</div></div>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":"172 ","pages":"Article 111148"},"PeriodicalIF":3.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146100076","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":"Immune divergence in rainbow trout lines selectively bred for F. psychrophilum resistance or susceptibility revealed by challenge with Weissella tructae.","authors":"Gregory D Wiens, Christopher C Chadwick, Keira Osbourn, Qin Fu, Ross M Reid, Travis Moreland, Timothy J Welch, Timothy D Leeds, David P Marancik","doi":"10.1016/j.fsi.2026.111387","DOIUrl":"10.1016/j.fsi.2026.111387","url":null,"abstract":"<p><p>Host genetic resistance can be improved through selective breeding, yet underlying immune mechanisms often remain unknown due to varying pathogen burden. In previous research, rainbow trout lines, ARS-Fp-R (resistant, R-line) and ARS-Fp-S (susceptible, S-line), were bred for differential resistance to Flavobacterium psychrophilum, but mechanisms remain unclear and study has been confounded by the higher F. psychrophilum load in the susceptible line. Here, we separate line-specific traits from pathogen-load driven effects, by challenging with Weissella tructae, a pathogen for which both lines exhibit equivalent susceptibility. After 3 to 6 days post-challenge with W. tructae, we report the divergent and shared cellular and cytokine profiles. The infected R-line fish exhibited higher granulocyte levels post-challenge, a trait also observed in its response to F. psychrophilum, while S-line fish had a more severe depletion of circulating leukocytes and IgM + B cells. Proteomic analysis identified 50 infection-induced blood proteins. Using novel salmonid biomarker assays, the S-line exhibited a 6-fold higher tumor necrosis factor-alpha (TNFα) and elevated precerebellin (PCB). In contrast, the R-line showed 3-fold higher baseline complement factor H-like-1 protein (CFHL-1), and a trend toward elevated serum amyloid A (SAA). Other biomarkers, including Cath2, GDF-15, haptoglobin, and C1q-LP3 increased post-infection but did not differ between lines. Both lines exhibited similar granulomatous epicarditis and decreased plasma fibrinogen. Despite equivalent susceptibility to W. tructae, these lines demonstrate divergent cellular and cytokine responses, suggesting a shift in immune architecture due to selective breeding. The novel biomarker assays provide valuable tools for monitoring immune health and precision breeding in salmonid aquaculture.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111387"},"PeriodicalIF":3.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147812645","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":"FlgE-TLR5 interaction and its association with immune and microbiota responses in Asian swamp eel fed Bacillus velezensis.","authors":"Nourhan Nassar, Ibrar Muhammad Khan, Samiullah Khan, Abdul Qadeer, Ni Du, Zaigui Wang","doi":"10.1016/j.fsi.2026.111352","DOIUrl":"10.1016/j.fsi.2026.111352","url":null,"abstract":"<p><p>Bacillus velezensis has emerged as a promising probiotic in aquaculture; however, the mechanisms by which it modulates host innate immunity and gut homeostasis in teleost fish remain poorly understood. In this study, interactions among B. velezensis D1, TLR5-associated immune signaling, and gut microbiota dynamics were investigated using an integrated in vitro and in vivo model in Asian swamp eel. In vitro interaction assays demonstrated a selective interaction between eel TLR5 and the flagellar hook protein FlgE, which was validated by co-immunoprecipitation, showing a distinct band at approximately 48 kDa. No interaction was detected with FliC or FliD, and all negative controls were non-reactive, indicating selective association between FlgE and eel TLR5. This interaction suggests a potential link between TLR5-mediated probiotic sensing and downstream immune responses, which may be associated with subsequent intestinal remodeling and gut microbiota restructuring Dietary supplementation altered TLR5, IL-6, IL-1β, and TNF-α expression in spleen, liver, and gut, showing significant early upregulation (6-12 h, p < 0.01) and peak responses at 24-48 h (p < 0.001), with gene- and tissue-specific patterns. Histomorphological analysis revealed significant improvements in gut structure, including increased villus height and width, as well as intestinal wall and muscle layer thickness. Furthermore, 16S rRNA gene sequencing showed that probiotic supplementation significantly altered gut microbial communities. The probiotic group exhibited higher microbial richness, with 527 distinct OTUs compared to 239 in the control group. Beneficial phyla, including Firmicutes and Actinobacteria, increased, while Proteobacteria decreased. These findings suggest that TLR5-associated immune responses may be linked to the observed restructuring of gut microbiota, indicating a coordinated relationship between host immune activation and microbial community modulation following probiotic supplementation. Overall, this study provides insights into host-microbe interactions and supports the potential application of B. velezensis as a probiotic in sustainable aquaculture.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111352"},"PeriodicalIF":3.9,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147812430","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":"Identification of the inhibitors of apoptosis proteins (IAPs) gene family in Portunus trituberculatus and its immune defense under Vibrio parahaemolyticus stress.","authors":"Jiayi Pan, Hangfeng Pan, Bingjie Zhang, Xianfa Zhou, Jianjian Lv, Xuezhong Wang, Dongfang Sun, Baoquan Gao","doi":"10.1016/j.fsi.2026.111384","DOIUrl":"10.1016/j.fsi.2026.111384","url":null,"abstract":"<p><p>Inhibitors of apoptosis proteins (IAPs) are endogenous apoptosis regulators conserved in many species. We used bioinformatics approaches, identified six members of the IAP gene family (named PtIAP-01 to PtIAP-06) in the genome of Portunus trituberculatus. We phylogenetically classified these PtIAPs into four distinct subfamilies, namely BIRC5, BIRC6, BIRC7-A, and BIRC7-B. All identified PtIAPs contained the characteristic baculoviral IAP repeat (BIR) domain. In addition, some PtIAP members were found to possess additional functional domains, including RING finger or UBC. The expression levels of the PtIAPs were tissue-specific. PtIAP-01 was highly expressed in immune-related tissues (intestine and hepatopancreas), PtIAP-05 dominated in muscle, while PtIAP-02, -03, -04, and -06 showed preferential expression in the eyestalk. Following Vibrio parahaemolyticus injection, the expression levels of PtIAP-01, -02 and -05 were significantly upregulated, reaching 1.64-, 3.48-, and 4.18-fold of the control group, respectively, indicating their potential involvement in anti-pathogen immunity. Fluorescence in situ hybridization (FISH), RNA interference (RNAi) and terminal deoxynucleotidyl transferase nick-end-labeling (TUNEL) apoptosis assays validated their function. FISH confirmed that PtIAP-01, -02, and -05 were in both the nucleus and cytoplasm of hepatopancreatic cells. Their fluorescence signals got stronger after V. parahaemolyticus infection (PtIAP-05 strongest). RNAi and TUNEL demonstrated that knockdown of PtIAP-01, -02, and -05 significantly increased the mortality and apoptosis rates of P. trituberculatus after V. parahaemolyticus challenge, and significant upregulation of downstream apoptotic effector genes (PtCaspase-1, -3, -8). These findings offer new insights into the innate immune mechanisms of crustaceans and lay a foundation for breeding disease-resistant strains.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111384"},"PeriodicalIF":3.9,"publicationDate":"2026-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147812660","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 host endogenous reverse transcriptase in response to white spot syndrome virus infection in Penaeus monodon.","authors":"Prapatsorn Wongkhaluang, Suparat Taengchaiyaphum, Thanaporn Wongpim, Suchitraporn Sukthaworn, Hideki Nakayama, Siripong Thitamadee, Kallaya Sritunyalucksana","doi":"10.1016/j.fsi.2026.111380","DOIUrl":"10.1016/j.fsi.2026.111380","url":null,"abstract":"<p><p>It was first hypothesized in 2009 that endogenous host reverse transcriptase (eRT) arising from retrotransposon elements in arthropod genomes would be critical for defense against viral pathogens in crustaceans and insects. This was not proven until 2016 in insects. In the succeeding 20 years, insect studies have confirmed the eRT role in antiviral defenses that result in tolerated, persistent infections via viral accommodation mechanisms (VAM). In insects, eRT transcribes viral RNA fragments into viral copy DNA (vcDNA) in both linear (lvcDNA) and circular (cvcDNA) forms. These, in turn, give rise to small interfering RNA (siRNA) fragments to feed the host RNA interference (RNAi) mechanism. At the same time, some vcDNA fragments are integrated into the host genome as endogenous viral elements (EVE), that can also give rise to siRNA. Studies with shrimp have progressed more slowly but results so far have mimicked those revealed with insects. Here we describe the presence and functional activity of a 5383 bp-RT-related gene from a retrotransposon in the black tiger shrimp Penaeus monodon upon challenge with white spot syndrome virus (WSSV). It encompasses four conserved domains of protease (retropepsin), reverse transcriptase (RT-RNase H), transposase, and integrase as a single ORF of 1248 deduced amino acids. The recombinant protein of a conserved 408-amino acid RT-RNase H domain, designated as Pm-eRT was expressed and found to possess reverse transcriptase activity. During WSSV infection, Pm-eRT was upregulated in shrimp hemocytes and pleopods and DNA/RNA hybrids in hemocytes were detected. The DNA/RNA hybrid signals were translocated from the plasma membrane to the nuclear membrane in the shrimp that survived WSSV infection with low viral loads. Pharmacological inhibition of Pm-eRT activity using azidothymidine (AZT) resulted in enhanced viral replication and accelerated shrimp mortality. Collectively, these findings support those described for insects, paving the way to further work on details of VAM in shrimp with the ultimate aim of developing genetically viral-tolerant breeding stocks for shrimp cultivation.</p>","PeriodicalId":12127,"journal":{"name":"Fish & shellfish immunology","volume":" ","pages":"111380"},"PeriodicalIF":3.9,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147766626","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}