Pub Date : 2026-01-27DOI: 10.1016/j.jip.2026.108551
Xiaohui Zou , Haiyan Zhang , Sheng Liu , Junchao Xu , Zhihua Lin , Qinggang Xue
Several Vibrio spp. are important shellfish pathogens. Vibrio mediterranei, notorious for its pathogenicity to bivalve larvae, contains a pathogenicity island, TCP-PAI, homologous to the Vibrio cholerae TCP gene cluster. This study explored the role of TCP-PAI in V. mediterranei pathogenicity by comparing TCP-PAI (+) and TCP-PAI (−) strains isolated from larval and juvenile Chinese razor clams (Sinonovacula constricta) and blood clams (Tegillarca granosa). Three independent PCR assays were developed to detect TCP-PAI, tcpA, and tcpB, respectively. The assay amplified a 949 bp band for TCP-PAI (−) strains, a 13375 bp band for TCP-PAI (+) strains, a 415 bp band for tcpA, and a 400 bp band for tcpB, with detection limits of 1.98 × 103 copies/µL for TCP-PAI and 1.38 × 103 copies/µL for tcpA and tcpB. A total of 352 Vibrio spp. isolates were collected from larval clams, including 300 from healthy razor clams, 6 from healthy blood clams, and 46 from diseased blood clams. Three isolates (1% of total) from healthy razor clams were identified as V. mediterranei and all were determined to be TCP-PAI (−). Ten isolates (21.7% of total) from diseased blood clams were identified as V. mediterranei and all were TCP-PAI (+). No V. mediterranei was detected in healthy blood clams. Infection experiments showed TCP-PAI (+) strains were associated with up to 99% and 96.67% mortality in razor clams and blood clams, respectively, significantly higher than TCP-PAI (−) strains (71% and 48.89%). These findings highlight TCP-PAI as a key virulence factor in V. mediterranei pathogenicity. The developed PCR assays provide a tool for further studies on TCP-PAI’s role and transmission, offering insights into V. mediterranei pathogenesis in bivalves.
{"title":"Elevated virulence in TCP-PAI carrying strains indicates the pathogenicity island’s important role in Vibrio mediterranei pathogenicity to bivalves","authors":"Xiaohui Zou , Haiyan Zhang , Sheng Liu , Junchao Xu , Zhihua Lin , Qinggang Xue","doi":"10.1016/j.jip.2026.108551","DOIUrl":"10.1016/j.jip.2026.108551","url":null,"abstract":"<div><div>Several <em>Vibrio</em> spp. are important shellfish pathogens. <em>Vibrio mediterranei</em>, notorious for its pathogenicity to bivalve larvae, contains a pathogenicity island, TCP-PAI, homologous to the <em>Vibrio cholerae</em> TCP gene cluster. This study explored the role of TCP-PAI in <em>V. mediterranei</em> pathogenicity by comparing TCP-PAI (+) and TCP-PAI (−) strains isolated from larval and juvenile Chinese razor clams (<em>Sinonovacula constricta</em>) and blood clams (<em>Tegillarca granosa</em>). Three independent PCR assays were developed to detect TCP-PAI, <em>tcpA</em>, and <em>tcpB</em>, respectively. The assay amplified a 949 bp band for TCP-PAI (−) strains, a 13375 bp band for TCP-PAI (+) strains, a 415 bp band for <em>tcpA</em>, and a 400 bp band for <em>tcpB</em>, with detection limits of 1.98 × 10<sup>3</sup> copies/µL for TCP-PAI and 1.38 × 10<sup>3</sup> copies/µL for <em>tcpA</em> and <em>tcpB</em>. A total of 352 <em>Vibrio</em> spp. isolates were collected from larval clams, including 300 from healthy razor clams, 6 from healthy blood clams, and 46 from diseased blood clams. Three isolates (1% of total) from healthy razor clams were identified as <em>V. mediterranei</em> and all were determined to be TCP-PAI (−). Ten isolates (21.7% of total) from diseased blood clams were identified as <em>V. mediterranei</em> and all were TCP-PAI (+). No <em>V. mediterranei</em> was detected in healthy blood clams. Infection experiments showed TCP-PAI (+) strains were associated with up to 99% and 96.67% mortality in razor clams and blood clams, respectively, significantly higher than TCP-PAI (−) strains (71% and 48.89%). These findings highlight TCP-PAI as a key virulence factor in <em>V. mediterranei</em> pathogenicity. The developed PCR assays provide a tool for further studies on TCP-PAI’s role and transmission, offering insights into <em>V. mediterranei</em> pathogenesis in bivalves.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108551"},"PeriodicalIF":2.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.jip.2026.108556
Nuria Vázquez, Gustavo Mariluan, Pablo E Penchaszadeh, Silvina Van der Molen, Nicolás Ortíz, Eunji Park, Brian Leander, Florencia Cremonte
Dicyemids are highly specialized parasites found in the renal sacs of most cephalopod species. In this study, the description of Dicyemaplatycephalum is expanded from specimens infecting Octopus tehuelchus from the Patagonian coasts. The species is redescribed with histological sections, scanning electron microscopy, and molecular phylogenetic analysis of 18S rDNA sequences. This species had a distinctive disk shaped calotte with a configuration of ten cells (4 + 4 + 2), which is typical for the cephalic swelling of the genus. Histological sections revealed renal epithelial tissue with no signs of severe tissue damage, except in cases of heavy infection, where deformation of the epithelial folds and renal tubule obstruction were observed. Scanning electron micrographs showed the ciliated calotte inserted in renal crypts of host tissue. Many aspects of the dicyemid biology remain unknown, including how an infusoriform larva searches for and infects a new host. Attempts were made to infect uninfected juvenile octopuses experimentally reared, with potential infective larvae using three different exposure assays, but the attempts were unsuccessful. Nonetheless, this study broadens the description of D. platycephalum in the southern hemisphere using molecular phylogenetic data and contributes to the general understanding of the associations between dicyemid parasites and their cephalopod hosts.
{"title":"First Record and extended description of Dicyema platycephalum Penchaszadeh1969 (Dicyemida: Dicyemidae) in Octopus tehuelchus from northern Patagonia, SW Atlantic.","authors":"Nuria Vázquez, Gustavo Mariluan, Pablo E Penchaszadeh, Silvina Van der Molen, Nicolás Ortíz, Eunji Park, Brian Leander, Florencia Cremonte","doi":"10.1016/j.jip.2026.108556","DOIUrl":"10.1016/j.jip.2026.108556","url":null,"abstract":"<p><p>Dicyemids are highly specialized parasites found in the renal sacs of most cephalopod species. In this study, the description of Dicyemaplatycephalum is expanded from specimens infecting Octopus tehuelchus from the Patagonian coasts. The species is redescribed with histological sections, scanning electron microscopy, and molecular phylogenetic analysis of 18S rDNA sequences. This species had a distinctive disk shaped calotte with a configuration of ten cells (4 + 4 + 2), which is typical for the cephalic swelling of the genus. Histological sections revealed renal epithelial tissue with no signs of severe tissue damage, except in cases of heavy infection, where deformation of the epithelial folds and renal tubule obstruction were observed. Scanning electron micrographs showed the ciliated calotte inserted in renal crypts of host tissue. Many aspects of the dicyemid biology remain unknown, including how an infusoriform larva searches for and infects a new host. Attempts were made to infect uninfected juvenile octopuses experimentally reared, with potential infective larvae using three different exposure assays, but the attempts were unsuccessful. Nonetheless, this study broadens the description of D. platycephalum in the southern hemisphere using molecular phylogenetic data and contributes to the general understanding of the associations between dicyemid parasites and their cephalopod hosts.</p>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":" ","pages":"108556"},"PeriodicalIF":2.4,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146086015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1016/j.jip.2026.108552
Qiong Yu, Qingsheng Qu, Shiyi Lu, Pingyang Wang, Li Sui, Jie Cheng, Xudong Tang, Ping Qian
Alternative splicing is a crucial mechanism in higher eukaryotes that enhances the structural complexity of the transcriptome and augments protein functional diversity. The regulation of alternative splicing is governed by splicing factors, which influence disease development by modulating this process. Pebrine disease, caused by Nosema bombycis (N. bombycis) infection, is a significant disease affecting the sericulture industry. Recent years have seen an increase in omics research, with numerous biochemical and molecular biological studies focusing on the complex interactions among various biomolecules (genes, RNA, proteins, metabolites) within the silkworm (Bombyx mori). However, there is a paucity of research on the alternative splicing gene response of silkworm during N. bombycis infection, and the role of alternative splicing genes in this process remains unclear. This study analyzes a differential alternative spliced gene Bmupp1, which responds to N. bombycis infection in silkworm. Subcellular localization revealed that Bmupp1-X1 is located in the cytoplasm, while Bmupp1-X2, X3, and X4 are localized in the nucleus. Overexpression of Bmupp1 demonstrated that Bmupp1-X2 and Bmupp1-X4 exhibit uridine phosphorylase (UPP) enzymatic activity. Bmupp1-X2 and Bmupp1-X4 inhibit N. bombycis replication, while Bmupp1-X1 and Bmupp1-X3 have no effect. Mini-gene assays and RNA interference of the splicing factor SC35 revealed that SC35 regulates the alternative splicing of Bmupp1 in a dose-dependent manner, specifically influencing the splicing of Bmupp1-X2 and Bmupp1-X4. RT-qPCR analysis suggested that splicing factor SC35 may play distinct roles during the early and late stages of N. bombycis infection. In conclusion, during the early and late stages of N. bombycis infection, splicing factor SC35 regulates the alternative splicing of Bmupp1, thereby enhancing uridine phosphorylase enzymatic activity to suppress N. bombycis proliferation.
选择性剪接是高等真核生物的一个重要机制，它增强了转录组结构的复杂性，增加了蛋白质功能的多样性。选择性剪接的调节是由剪接因子控制的，剪接因子通过调节这一过程来影响疾病的发展。由家蚕微孢子虫（Nosema bombycis， N. bombycis）感染引起的微孢子虫病（Pebrine disease）是影响蚕业的重大病害。近年来，组学研究有所增加，大量的生化和分子生物学研究集中在家蚕（Bombyx mori）体内各种生物分子（基因、RNA、蛋白质、代谢物）之间复杂的相互作用。然而，目前关于家蚕在感染蚕蛾过程中选择性剪接基因反应的研究还很缺乏，也不清楚选择性剪接基因在这一过程中的作用。本研究分析了家蚕对家蝇感染的差异选择性剪接基因Bmupp1。亚细胞定位显示Bmupp1-X1位于细胞质中，而Bmupp1-X2、X3和X4位于细胞核中。Bmupp1的过表达表明Bmupp1- x2和Bmupp1- x4具有尿苷磷酸化酶（UPP）活性。Bmupp1-X2和Bmupp1-X4对家蚕复制有抑制作用，而Bmupp1-X1和Bmupp1-X3对家蚕复制无影响。剪接因子SC35的Mini-gene实验和RNA干扰显示，SC35以剂量依赖的方式调节Bmupp1的选择性剪接，特别是影响Bmupp1- x2和Bmupp1- x4的剪接。RT-qPCR分析表明，剪接因子SC35在家蚕感染的早期和晚期可能发挥着不同的作用。综上所述，在家蚕感染的早期和后期，剪接因子SC35调控Bmupp1的选择性剪接，从而增强尿苷磷酸化酶活性，抑制家蚕增殖。
{"title":"Splicing factor SC35 inhibits Nosema bombycis proliferation by regulating the alternative splicing of Bmupp1.","authors":"Qiong Yu, Qingsheng Qu, Shiyi Lu, Pingyang Wang, Li Sui, Jie Cheng, Xudong Tang, Ping Qian","doi":"10.1016/j.jip.2026.108552","DOIUrl":"https://doi.org/10.1016/j.jip.2026.108552","url":null,"abstract":"<p><p>Alternative splicing is a crucial mechanism in higher eukaryotes that enhances the structural complexity of the transcriptome and augments protein functional diversity. The regulation of alternative splicing is governed by splicing factors, which influence disease development by modulating this process. Pebrine disease, caused by Nosema bombycis (N. bombycis) infection, is a significant disease affecting the sericulture industry. Recent years have seen an increase in omics research, with numerous biochemical and molecular biological studies focusing on the complex interactions among various biomolecules (genes, RNA, proteins, metabolites) within the silkworm (Bombyx mori). However, there is a paucity of research on the alternative splicing gene response of silkworm during N. bombycis infection, and the role of alternative splicing genes in this process remains unclear. This study analyzes a differential alternative spliced gene Bmupp1, which responds to N. bombycis infection in silkworm. Subcellular localization revealed that Bmupp1-X1 is located in the cytoplasm, while Bmupp1-X2, X3, and X4 are localized in the nucleus. Overexpression of Bmupp1 demonstrated that Bmupp1-X2 and Bmupp1-X4 exhibit uridine phosphorylase (UPP) enzymatic activity. Bmupp1-X2 and Bmupp1-X4 inhibit N. bombycis replication, while Bmupp1-X1 and Bmupp1-X3 have no effect. Mini-gene assays and RNA interference of the splicing factor SC35 revealed that SC35 regulates the alternative splicing of Bmupp1 in a dose-dependent manner, specifically influencing the splicing of Bmupp1-X2 and Bmupp1-X4. RT-qPCR analysis suggested that splicing factor SC35 may play distinct roles during the early and late stages of N. bombycis infection. In conclusion, during the early and late stages of N. bombycis infection, splicing factor SC35 regulates the alternative splicing of Bmupp1, thereby enhancing uridine phosphorylase enzymatic activity to suppress N. bombycis proliferation.</p>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"108552"},"PeriodicalIF":2.4,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146113300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1016/j.jip.2026.108554
Jacinta R. Agius , Danielle Ackerly , Angus C. Watson , Monique L Smith , Lachlan Hulands , Joshua McIntyre , Travis Beddoe , Karla J Helbig
Abalone (Haliotis sp.) are marine organisms of significant ecological and economic importance. However, disease outbreaks, particularly caused by Haliotid herpesvirus (HaHV-1), pose a major threat to the global aquaculture industry. HaHV-1 causes Abalone Viral Ganglioneuritis (AVG) and has led to significant economic losses due to mass mortality in farmed and wild abalone in regions such as China, Taiwan, and Australia. The current study investigated the effect of age on the susceptibility of Australian hybrid abalone to HaHV-1 and the potential of immune priming as a strategy to protect abalone from HaHV-1 infection. Using a co-housed immersion challenge model, we found that abalone less than one year of age were significantly less susceptible to HaHV-1 infection and exhibit less pronounced clinical signs of HaHV-1 infection when compared to adults. Additionally, immune priming adult abalone with poly(I:C) prior to viral challenge provided protection against HaHV-1 when compared to abalone primed with a bacterial antigen, Flagellin-A and unprimed controls. We also determined that the use of pedal swabs is a less invasive method for confirming positive HaHV-1 infections, but not for determining comparative viral loads. These findings are pivotal in developing preventative strategies against HaHV-1 in aquaculture and highlight the need for further research on immune priming and age-related susceptibility in abalone.
{"title":"Reducing the impact of HaHV-1 in Australian abalone: The role of age and immune priming","authors":"Jacinta R. Agius , Danielle Ackerly , Angus C. Watson , Monique L Smith , Lachlan Hulands , Joshua McIntyre , Travis Beddoe , Karla J Helbig","doi":"10.1016/j.jip.2026.108554","DOIUrl":"10.1016/j.jip.2026.108554","url":null,"abstract":"<div><div>Abalone (<em>Haliotis sp</em>.) are marine organisms of significant ecological and economic importance. However, disease outbreaks, particularly caused by Haliotid herpesvirus (HaHV-1), pose a major threat to the global aquaculture industry. HaHV-1 causes Abalone Viral Ganglioneuritis (AVG) and has led to significant economic losses due to mass mortality in farmed and wild abalone in regions such as China, Taiwan, and Australia. The current study investigated the effect of age on the susceptibility of Australian hybrid abalone to HaHV-1 and the potential of immune priming as a strategy to protect abalone from HaHV-1 infection. Using a co-housed immersion challenge model, we found that abalone less than one year of age were significantly less susceptible to HaHV-1 infection and exhibit less pronounced clinical signs of HaHV-1 infection when compared to adults. Additionally, immune priming adult abalone with poly(I:C) prior to viral challenge provided protection against HaHV-1 when compared to abalone primed with a bacterial antigen, Flagellin-A and unprimed controls. We also determined that the use of pedal swabs is a less invasive method for confirming positive HaHV-1 infections, but not for determining comparative viral loads. These findings are pivotal in developing preventative strategies against HaHV-1 in aquaculture and highlight the need for further research on immune priming and age-related susceptibility in abalone.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108554"},"PeriodicalIF":2.4,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Penaeid shrimp aquaculture is expanding worldwide, but recurrent infectious diseases remain a major threat to production. Interestingly, some farming environments sustain long-term stable production performance. To investigate the microbial basis of this condition, we performed 16S rRNA gene-based bacterial community analysis of rearing water from two farms with different reported disease histories. The stable production performance farm (Taketomijima) was characterized by a low-diversity bacterial community dominated by unclassified Rhodobacteraceae, whereas the variable production performance farm (Tanegashima) harbored a highly diverse and heterogeneous community. Despite the higher diversity, the variable production performance environment showed less stability across ponds, while the stable production performance farm exhibited a uniform and resilient microbiome structure. These results demonstrate that community composition and dominance of specific taxa, rather than overall diversity, are critical for disease prevalence. Our findings provide new insight into microbial factors of disease outcomes and lay the foundation for microbiome-informed management strategies to improve the sustainability and resilience of shrimp aquaculture.
{"title":"Bacterial communities in pond water of kuruma shrimp Penaeus japonicus farms with different reported disease histories","authors":"Hajime Yuasa , Denise Angelina Bermudez , Kayo Konishi , Miho Furukawa , Reiko Nozaki , Shotaro Morita , Kenichi Ozaki , Hidehiro Kondo , Ikuo Hirono , Keiichiro Koiwai","doi":"10.1016/j.jip.2026.108555","DOIUrl":"10.1016/j.jip.2026.108555","url":null,"abstract":"<div><div>Penaeid shrimp aquaculture is expanding worldwide, but recurrent infectious diseases remain a major threat to production. Interestingly, some farming environments sustain long-term stable production performance. To investigate the microbial basis of this condition, we performed 16S rRNA gene-based bacterial community analysis of rearing water from two farms with different reported disease histories. The stable production performance farm (Taketomijima) was characterized by a low-diversity bacterial community dominated by unclassified Rhodobacteraceae, whereas the variable production performance farm (Tanegashima) harbored a highly diverse and heterogeneous community. Despite the higher diversity, the variable production performance environment showed less stability across ponds, while the stable production performance farm exhibited a uniform and resilient microbiome structure. These results demonstrate that community composition and dominance of specific taxa, rather than overall diversity, are critical for disease prevalence. Our findings provide new insight into microbial factors of disease outcomes and lay the foundation for microbiome-informed management strategies to improve the sustainability and resilience of shrimp aquaculture.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108555"},"PeriodicalIF":2.4,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1016/j.jip.2026.108553
Motahareh Amiri Domari , Abbas Khani , Najmeh Sahebzadeh , Mohsen Najimi , Mohammad Mehrabadi
Emerging research underscores the critical roles of host-associated microbiota in modulating immunity and disease resistance in insects. However, the interplay between gut microbes and innate immune pathways remains incompletely understood in lepidopteran pests. This study investigates if manipulation of the gut microbiome affects immune responses and pathogen susceptibility in Helicoverpa armigera larvae. To do this, the gut microbiome of the larvae was removed using antibiotic treatment. Subsequently, the expression of antimicrobial peptides (AMPs) including attacin and defensin, and antioxidant genes including superoxide dismutase (SOD), dual oxidase (DUOX) and NADPH oxidase (NOX) were assessed following challenge with Bacillus thuringiensis (Bt) and Beauveria bassiana (Bb). Our results revealed that microbiome depletion reduced the expression of attacin and defensin in fat body and gut, and suppressed SOD gene expression in the gut. The bioassay tests showed that depletion of microbiota resulted in increased larval vulnerability to the pathogens compared to the control larvae. We also tested whether microbial infection affects gut microbiota and found that intrahemocoelic microbial injection induced both humoral and gut immunity, resulting in suppression of gut microbiota, highlighting a crosslink between humoral and gut immunity. Together, these results underscore a conserved requirement for microbiota-derived signals in priming specific innate immune pathways and provide insight into how microbiome manipulation may impact the success of biological control strategies. These findings suggest that targeted manipulation of the gut microbiome could be harnessed to enhance pest susceptibility to biocontrol agents, thereby offering a promising avenue for improving microbial pest control.
{"title":"Gut microbes modulate Helicoverpa armigera immunity and affect its susceptibility to microbial pathogens","authors":"Motahareh Amiri Domari , Abbas Khani , Najmeh Sahebzadeh , Mohsen Najimi , Mohammad Mehrabadi","doi":"10.1016/j.jip.2026.108553","DOIUrl":"10.1016/j.jip.2026.108553","url":null,"abstract":"<div><div>Emerging research underscores the critical roles of host-associated microbiota in modulating immunity and disease resistance in insects. However, the interplay between gut microbes and innate immune pathways remains incompletely understood in lepidopteran pests. This study investigates if manipulation of the gut microbiome affects immune responses and pathogen susceptibility in <em>Helicoverpa armigera</em> larvae. To do this, the gut microbiome of the larvae was removed using antibiotic treatment. Subsequently, the expression of antimicrobial peptides (AMPs) including attacin and defensin, and antioxidant genes including superoxide dismutase (SOD), dual oxidase (DUOX) and NADPH oxidase (NOX)<!--> <!-->were assessed following challenge with <em>Bacillus thuringiensis</em> (Bt) and <em>Beauveria bassiana</em> (Bb). Our results revealed that microbiome depletion reduced the expression of attacin and defensin in fat body and gut, and suppressed SOD gene expression in the gut. The bioassay tests showed that depletion of microbiota resulted in increased larval vulnerability to the pathogens compared to the control larvae. We also tested whether microbial infection affects gut microbiota and found that intrahemocoelic microbial injection induced both humoral and gut immunity, resulting in suppression of gut microbiota, highlighting a crosslink between humoral and gut immunity. Together, these results underscore a conserved requirement for microbiota-derived signals in priming specific innate immune pathways and provide insight into how microbiome manipulation may impact the success of biological control strategies. These findings suggest that targeted manipulation of the gut microbiome could be harnessed to enhance pest susceptibility to biocontrol agents, thereby offering a promising avenue for improving microbial pest control.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108553"},"PeriodicalIF":2.4,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chalkbrood fungus Ascosphaera apis (A. apis) produces miRNA-like small RNAs (milRNAs) that may modulate honey bee (Apis mellifera) larval biology through cross-kingdom RNA interference (ckRNAi). We identified 380, 106, 107, and 110 highly expressed milRNAs (HmilRNAs) in pure spores and infected larval guts at days 4, 5, and 6, respectively. Eighteen HmilRNAs were conserved across all groups, forming a complex regulatory network predicted to target 188 host genes (6,057 mRNAs) associated with critical signaling pathways, including Wnt, Hippo, mTOR, MAPK, and Toll/Imd. Among these, aap-milR-11980-x was validated to directly target the ecdysone-inducible gene E75 and the transcriptional repressor tramtrack (TTK). Dual-luciferase assays confirmed that aap-milR-11980-x represses these targets via specific binding to their 3'-UTR. In vivo modulation of aap-milR-11980-x in 6-day-old larval guts using agomirs and antagomirs successfully altered E75, TTK, and antimicrobial peptide (AMP) transcript levels. However, despite significant molecular regulation, no statistically significant difference in larval survival was observed between treatment groups (P > 0.05). This discrepancy suggests that while aap-milR-11980-x effectively rewires host gene expression, its primary function may be to induce sub-lethal physiological changes, such as developmental delay or immune modulation, rather than acute lethality. These findings indicate that A. apis HmilRNAs fine-tune host cellular responses, potentially to extend the temporal window for fungal development or resource acquisition, highlighting a sophisticated layer of molecular manipulation in the A. apis-honey bee interaction.
{"title":"Ascosphaera apis-derived microRNA-like RNAs mediate cross-kingdom regulation of gene expression in western honeybee larvae.","authors":"Xiaoxue Fan, Nian Fan, Tao Wu, Jing Kang, Jiarun Yang, Jing Tian, Xihan Luo, Dafu Chen, Jianfeng Qiu, Rui Guo","doi":"10.1016/j.jip.2026.108534","DOIUrl":"10.1016/j.jip.2026.108534","url":null,"abstract":"<p><p>Chalkbrood fungus Ascosphaera apis (A. apis) produces miRNA-like small RNAs (milRNAs) that may modulate honey bee (Apis mellifera) larval biology through cross-kingdom RNA interference (ckRNAi). We identified 380, 106, 107, and 110 highly expressed milRNAs (HmilRNAs) in pure spores and infected larval guts at days 4, 5, and 6, respectively. Eighteen HmilRNAs were conserved across all groups, forming a complex regulatory network predicted to target 188 host genes (6,057 mRNAs) associated with critical signaling pathways, including Wnt, Hippo, mTOR, MAPK, and Toll/Imd. Among these, aap-milR-11980-x was validated to directly target the ecdysone-inducible gene E75 and the transcriptional repressor tramtrack (TTK). Dual-luciferase assays confirmed that aap-milR-11980-x represses these targets via specific binding to their 3'-UTR. In vivo modulation of aap-milR-11980-x in 6-day-old larval guts using agomirs and antagomirs successfully altered E75, TTK, and antimicrobial peptide (AMP) transcript levels. However, despite significant molecular regulation, no statistically significant difference in larval survival was observed between treatment groups (P > 0.05). This discrepancy suggests that while aap-milR-11980-x effectively rewires host gene expression, its primary function may be to induce sub-lethal physiological changes, such as developmental delay or immune modulation, rather than acute lethality. These findings indicate that A. apis HmilRNAs fine-tune host cellular responses, potentially to extend the temporal window for fungal development or resource acquisition, highlighting a sophisticated layer of molecular manipulation in the A. apis-honey bee interaction.</p>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":" ","pages":"108534"},"PeriodicalIF":2.4,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146046679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.jip.2026.108533
Clara Martínez , Sergio Rodriguez , Alba Trueba , Diego Rey-Varela , Alicia E. Toranzo , Ana L. Dieguez , Javier Dubert
Bivalve aquaculture is a major component of global seafood production. However, its sustainability is severely threatened by recurrent outbreaks of vibriosis, caused by Vibrio europaeus that has emerged as a significant threat worldwide, affecting key aquaculture shellfish species. This study presents the first comprehensive characterization of the extracellular products (ECPs) and secretome of the mollusk pathogen Vibrio europaeus. A total of 108 different proteins were identified in the wild-type (WT) secretome, with the extracellular proteins VemA, VepA, and GbpA, accounting for nearly 70% of the total secreted protein content. A significant proportion of cytoplasmic proteins were also detected in the WT secretome, consistent with their secretion through outer membrane vesicles (OMVs) observed by electron microscopy. Functional assays confirmed that VemA is essential for virulence toward Manila clam juveniles (Ruditapes philippinarum), whereas VepA and GbpA appear to play complementary or modulatory roles. Surprisingly, simultaneous deletion of vemA, vepA, and gbpA genes induced extensive secretory reprogramming, with this mutant secreting 823 proteins, nearly eight times more than the WT, and exhibiting novel enzymatic activities. Approximately half of the secreted proteins in the triple mutant were cytoplasmic in origin, likely associated with a hypervesiculation phenotype observed by electron microscopy. Despite its expanded repertoire of virulence-associated proteins, the triple mutant displayed the lowest virulence in challenge assays, suggesting that the loss of the main ECPs triggers compensatory stress responses that remodel secretion but does not restore the virulence phenotype. Overall, these findings demonstrate that VemA, VepA, and GbpA are key determinants of virulence and secretory homeostasis in V. europaeus, revealing an adaptive mechanism linking OMV-mediated secretion, proteomic plasticity, and pathogenic potential in marine Vibrio species and provide better understanding how pathogens evolve to maintain or expand their virulence capacity.
{"title":"Uncovering how major extracellular proteins drive virulence and functional compensation in the mollusk pathogen Vibrio europaeus","authors":"Clara Martínez , Sergio Rodriguez , Alba Trueba , Diego Rey-Varela , Alicia E. Toranzo , Ana L. Dieguez , Javier Dubert","doi":"10.1016/j.jip.2026.108533","DOIUrl":"10.1016/j.jip.2026.108533","url":null,"abstract":"<div><div>Bivalve aquaculture is a major component of global seafood production. However, its sustainability is severely threatened by recurrent outbreaks of vibriosis, caused by <em>Vibrio europaeus</em> that has emerged as a significant threat worldwide, affecting key aquaculture shellfish species. This study presents the first comprehensive characterization of the extracellular products (ECPs) and secretome of the mollusk pathogen <em>Vibrio europaeus</em>. A total of 108 different proteins were identified in the wild-type (WT) secretome, with the extracellular proteins VemA, VepA, and GbpA, accounting for nearly 70% of the total secreted protein content. A significant proportion of cytoplasmic proteins were also detected in the WT secretome, consistent with their secretion through outer membrane vesicles (OMVs) observed by electron microscopy. Functional assays confirmed that VemA is essential for virulence toward Manila clam juveniles (<em>Ruditapes philippinarum</em>), whereas VepA and GbpA appear to play complementary or modulatory roles. Surprisingly, simultaneous deletion of <em>vemA</em>, <em>vepA</em>, and <em>gbpA</em> genes induced extensive secretory reprogramming, with this mutant secreting 823 proteins, nearly eight times more than the WT, and exhibiting novel enzymatic activities. Approximately half of the secreted proteins in the triple mutant were cytoplasmic in origin, likely associated with a hypervesiculation phenotype observed by electron microscopy. Despite its expanded repertoire of virulence-associated proteins, the triple mutant displayed the lowest virulence in challenge assays, suggesting that the loss of the main ECPs triggers compensatory stress responses that remodel secretion but does not restore the virulence phenotype. Overall, these findings demonstrate that VemA, VepA, and GbpA are key determinants of virulence and secretory homeostasis in <em>V. europaeus</em>, revealing an adaptive mechanism linking OMV-mediated secretion, proteomic plasticity, and pathogenic potential in marine <em>Vibrio</em> species and provide better understanding how pathogens evolve to maintain or expand their virulence capacity.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108533"},"PeriodicalIF":2.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146044193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.jip.2026.108549
Jianfeng Qiu , Fangji Wang , Xiang Li , Tao Wu , Xin Jing , Zhenzhen Zuo , Jing Tian , Dafu Chen , Rui Guo
The Ascosphaera apis infects the honeybee larval gut and causes chalkbrood disease, which impacts colony health and beekeeping production. Currently, the innate immune mechanisms by which honeybee larvae resist A. apis infection remain unclear. This study utilized nanopore sequencing technology to analyze differentially expressed transcripts (DETs) in A. apis-infected and uninfected Apis cerana cerana larval guts, and identified alternative splicing (AS) and alternative polyadenylation (APA) in honeybee genes. The results showed that 1,642, 1,281, and 1,377 DETs were detected on 1–3 days post-infection, respectively. Ten DETs were randomly selected from each group for RT-qPCR validation, and 26 DETs exhibited expression trends consistent with the nanopore sequencing results. A total of 5,476 AS events from 2,430 genes were identified in the larval guts during 1–3 days post-infection, with the number of AS events in the A. apis-infected group being higher than in the control group. Five randomly validated AS events matched the sequencing results. Additionally, 7,310 genes containing APA sites were identified, with the majority having more than five APA sites. Three genes were randomly selected, and their APA sites were validated. These findings provide preliminary insights into the roles of AS and APA at the transcript level in honeybee responses to A. apis infection.
api Ascosphaera感染蜜蜂幼虫肠道并引起白垩病，影响蜂群健康和养蜂生产。目前，蜜蜂幼虫抵抗蜜蜂感染的先天免疫机制尚不清楚。本研究利用纳米孔测序技术分析了蜜蜂感染和未感染的中华蜜蜂幼虫肠道的差异表达转录物（DETs），并鉴定了蜜蜂基因的选择性剪接（AS）和选择性聚腺苷酸化（APA）。结果显示，感染后1-3天，分别检测到1,642、1,281和1,377只DETs。从每组随机抽取10个DETs进行RT-qPCR验证，其中26个DETs的表达趋势与纳米孔测序结果一致。在感染后1-3天内，在幼虫肠道中共鉴定出2430个基因的5476个AS事件，其中蜜蜂感染组的AS事件数量高于对照组。5个随机验证的AS事件与测序结果相匹配。此外，7310个含有APA位点的基因被鉴定出来，其中大多数具有5个以上的APA位点。随机选取3个基因，对其APA位点进行验证。这些发现提供了AS和APA在转录水平上在蜜蜂对蜜蜂感染反应中的作用的初步见解。
{"title":"Ascosphaera apis invasion alters the expression pattern, alternative splicing and alternative polyadenylation of transcripts in the eastern honeybee larval gut","authors":"Jianfeng Qiu , Fangji Wang , Xiang Li , Tao Wu , Xin Jing , Zhenzhen Zuo , Jing Tian , Dafu Chen , Rui Guo","doi":"10.1016/j.jip.2026.108549","DOIUrl":"10.1016/j.jip.2026.108549","url":null,"abstract":"<div><div>The <em>Ascosphaera apis</em> infects the honeybee larval gut and causes chalkbrood disease, which impacts colony health and beekeeping production. Currently, the innate immune mechanisms by which honeybee larvae resist <em>A. apis</em> infection remain unclear. This study utilized nanopore sequencing technology to analyze differentially expressed transcripts (DETs) in <em>A. apis</em>-infected and uninfected <em>Apis cerana cerana</em> larval guts, and identified alternative splicing (AS) and alternative polyadenylation (APA) in honeybee genes. The results showed that 1,642, 1,281, and 1,377 DETs were detected on 1–3 days post-infection, respectively. Ten DETs were randomly selected from each group for RT-qPCR validation, and 26 DETs exhibited expression trends consistent with the nanopore sequencing results. A total of 5,476 AS events from 2,430 genes were identified in the larval guts during 1–3 days post-infection, with the number of AS events in the <em>A. apis</em>-infected group being higher than in the control group. Five randomly validated AS events matched the sequencing results. Additionally, 7,310 genes containing APA sites were identified, with the majority having more than five APA sites. Three genes were randomly selected, and their APA sites were validated. These findings provide preliminary insights into the roles of AS and APA at the transcript level in honeybee responses to <em>A. apis</em> infection.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108549"},"PeriodicalIF":2.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.jip.2026.108547
Rayan Nasreddine , Gül Ayyildiz , Tayssir El Hammar , Zhanerke Amangeldi , Rim El Jeni , Asime Filiz Caliskan Keçe , Luc Fillaudeau , Dietrich Stephan
The intensive damage caused by citrus pests such as Phyllocnistis citrella and Prays citri requires the use of efficient, safe, and eco-friendly control measures. This study reports the development, characterization, and evaluation of a novel fluid bed-dried formulation based on Bacillus thuringiensis kurstaki (Btk) strains, namely Lip and Blb1, produced via submerged fermentation on wheat bran. The concentrated pellets using Lip achieved mean values of 9.93 Log10 CFU/g dry matter (gdm) spores and 117 mg/gdm proteins, with post-formulation of 9.51 Log10 CFU/gdm and 15 mg/gdm, respectively. Number- and volume-based size distribution functions were analysed for dry formulations (Btk Lip, Btk Blb1, and Delfin®) and solubilized suspensions, demonstrating critical safety and application criteria associated with “fine” and “coarse” populations. For the Delfin® suspension, remaining “coarse” particles (>100 µm: 21.7 %) were specifically reported. Laboratory bioassays against P. citrella, confirmed no significant differences across all formulations, whereas for P. citri, and Spodoptera frugiperda the lethal concentration of 50 % (LC50) of Delfin® was significantly lower than Lip- and Blb1 formulations (p < 0.001). In a field trial against P. citrella, Lip and Blb1 induced significantly faster mortality (LT50 = 1.67 d and 1.61 d, respectively) than Delfin® (LT50 = 2.89 d, p < 0.001). This study addresses whether fluid bed–dried formulations of locally isolated Btk strains produced on wheat bran–based media can combine physicochemical robustness, effective dispersion, and high insecticidal efficacy against citrus pests, offering a sustainable alternative to commercial Btk products.
{"title":"Bioactivity and physical investigation of a novel fluid bed-dried Bacillus thuringiensis kurstaki formulation","authors":"Rayan Nasreddine , Gül Ayyildiz , Tayssir El Hammar , Zhanerke Amangeldi , Rim El Jeni , Asime Filiz Caliskan Keçe , Luc Fillaudeau , Dietrich Stephan","doi":"10.1016/j.jip.2026.108547","DOIUrl":"10.1016/j.jip.2026.108547","url":null,"abstract":"<div><div>The intensive damage caused by citrus pests such as <em>Phyllocnistis citrella</em> and <em>Prays citri</em> requires the use of efficient, safe, and eco-friendly control measures. This study reports the development, characterization, and evaluation of a novel fluid bed-dried formulation based on <em>Bacillus thuringiensis kurstaki</em> (Btk) strains, namely Lip and Blb1, produced via submerged fermentation on wheat bran. The concentrated pellets using Lip achieved mean values of 9.93 Log<sub>10</sub> CFU/g dry matter (gdm) spores and 117 mg/gdm proteins, with post-formulation of 9.51 Log<sub>10</sub> CFU/gdm and 15 mg/gdm, respectively. Number- and volume-based size distribution functions were analysed for dry formulations (Btk Lip, Btk Blb1, and Delfin®) and solubilized suspensions, demonstrating critical safety and application criteria associated with “fine” and “coarse” populations. For the Delfin® suspension, remaining “coarse” particles (>100 µm: 21.7 %) were specifically reported. Laboratory bioassays against <em>P. citrella</em>, confirmed no significant differences across all formulations, whereas for <em>P. citri</em>, and <em>Spodoptera frugiperda</em> the lethal concentration of 50 % (LC<sub>50</sub>) of Delfin® was significantly lower than Lip- and Blb1 formulations (p < 0.001). In a field trial against <em>P. citrella</em>, Lip and Blb1 induced significantly faster mortality (LT<sub>50</sub> = 1.67 d and 1.61 d, respectively) than Delfin® (LT<sub>50</sub> = 2.89 d, p < 0.001). This study addresses whether fluid bed–dried formulations of locally isolated Btk strains produced on wheat bran–based media can combine physicochemical robustness, effective dispersion, and high insecticidal efficacy against citrus pests, offering a sustainable alternative to commercial Btk products.</div></div>","PeriodicalId":16296,"journal":{"name":"Journal of invertebrate pathology","volume":"216 ","pages":"Article 108547"},"PeriodicalIF":2.4,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146040954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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