Pub Date : 2026-01-23DOI: 10.1016/j.vetmic.2026.110883
Alec Truswell , David Jordan , Stanley Pang , Tanya Cherrington , David J. Hampson , John Blinco , Sandy Adsett , Rebecca Abraham , Marc Stegger , Sam Abraham
Exudative epidermitis (EE) causes substantial morbidity and mortality in piglets. This study investigated the microbial ecology, antimicrobial resistance (AMR), and genomic diversity of Staphylococcus hyicus associated with an EE outbreak in an Australian piggery.
Lesion swabs from 20 affected piglets yielded 160 bacterial isolates (including S. hyicus and cohabiting species). Isolates underwent species identification, antimicrobial susceptibility testing, and whole-genome sequencing (WGS) of S. hyicus for AMR/virulence gene profiling and core-genome SNP analysis to assess genomic relatedness.
S. hyicus predominated among lesion isolates. Phenotypic testing showed varied AMR, with frequent resistance to erythromycin and tetracycline. WGS of 27 S. hyicus isolates identified five distinct genotypic AMR profiles, including combinations spanning multiple drug classes. All S. hyicus carried the exfoliative toxin gene shetA, and 24 also carried exhD.
Core-genome analysis indicated a highly clonal outbreak: 24/27 genomes differed by 0 core SNPs, with the remaining three closely related. Despite this clonality, resistance gene carriage varied across isolates. Consequently, reliance on a single colony to represent an outbreak could understate resistance and overstate treatability.
These findings support routine multi-isolate sampling to capture within-clone AMR variability, bolster antimicrobial selection during EE management, and inform consideration of autogenous vaccines targeting dominant outbreak clones.
{"title":"Genomic analysis of a porcine exudative epidermitis outbreak caused by Staphylococcus hyicus","authors":"Alec Truswell , David Jordan , Stanley Pang , Tanya Cherrington , David J. Hampson , John Blinco , Sandy Adsett , Rebecca Abraham , Marc Stegger , Sam Abraham","doi":"10.1016/j.vetmic.2026.110883","DOIUrl":"10.1016/j.vetmic.2026.110883","url":null,"abstract":"<div><div>Exudative epidermitis (EE) causes substantial morbidity and mortality in piglets. This study investigated the microbial ecology, antimicrobial resistance (AMR), and genomic diversity of <em>Staphylococcus hyicus</em> associated with an EE outbreak in an Australian piggery.</div><div>Lesion swabs from 20 affected piglets yielded 160 bacterial isolates (including <em>S. hyicus</em> and cohabiting species). Isolates underwent species identification, antimicrobial susceptibility testing, and whole-genome sequencing (WGS) of <em>S. hyicus</em> for AMR/virulence gene profiling and core-genome SNP analysis to assess genomic relatedness.</div><div><em>S. hyicus</em> predominated among lesion isolates. Phenotypic testing showed varied AMR, with frequent resistance to erythromycin and tetracycline. WGS of 27 <em>S. hyicus</em> isolates identified five distinct genotypic AMR profiles, including combinations spanning multiple drug classes. All <em>S. hyicus</em> carried the exfoliative toxin gene <em>shetA</em>, and 24 also carried <em>exhD</em>.</div><div>Core-genome analysis indicated a highly clonal outbreak: 24/27 genomes differed by 0 core SNPs, with the remaining three closely related. Despite this clonality, resistance gene carriage varied across isolates. Consequently, reliance on a single colony to represent an outbreak could understate resistance and overstate treatability.</div><div>These findings support routine multi-isolate sampling to capture within-clone AMR variability, bolster antimicrobial selection during EE management, and inform consideration of autogenous vaccines targeting dominant outbreak clones.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110883"},"PeriodicalIF":2.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079298","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}
Pub Date : 2026-01-22DOI: 10.1016/j.vetmic.2026.110893
Guangli Hu , Zhiqing Zhao , Liguo Gao , Rui Geng , Shengjin Liu , Hao Zhang , Yongchang Cao , Hanqin Shen , Chunyi Xue
Porcine group A rotavirus (PoRVA) is a widespread enteric pathogen that causes severe diarrheal outbreaks in swine herds, leading to considerable economic losses in China’s pig farming industry. From 2022–2024, a systematic surveillance was conducted across southern China, during which 5425 diarrheic samples were collected to assess the epidemiology of PoRVA. The results showed that PoRVA infections peaked in winter and spring, with monthly positivity rates ranging from 36 % to 68 % in southern regions. Genotyping of 103 VP4/VP7 sequences revealed the predominant VP7 genotypes G5 (43.69 %), G4 (23.39 %), and G9 (15.53 %), as well as the major VP4 genotypes P[13] (68.93 %), P[6] (10.68 %), and P[23] (9.71 %). Two PoRVA strains were successfully isolated from positive intestinal samples collected in Guangdong and Jiangsu provinces, designated RVA/Pig/China/JS/2024/G9P[23] (JS2024) and RVA/Pig/China/GD/2024/G5P[13] (GD2024), respectively. Experimental infection demonstrated that both isolates caused severe watery diarrhea in 3-day-old colostrum-deprived piglets, resulting in mortality rates of 40 % (2/5) for JS2024 and 20 % (1/5) for GD2024. A bivalent inactivated vaccine prepared with the two isolates (10^8 TCID50/mL per antigen, administered twice at a 14-day interval) elicited robust neutralizing antibody responses against both G5 and G9 genotypes. Furthermore, maternal immunization with the bivalent vaccine in pregnant sows resulted in efficient transfer of maternal antibodies to neonatal piglets. Piglets born to vaccinated sows exhibited significantly higher pre-challenge neutralizing antibody titers, developed only mild clinical diarrhea following JS2024 or GD2024 challenge, displayed substantially reduced fecal viral shedding, and showed 100 % survival, in contrast to unvaccinated litters, which experienced severe diarrhea, high viral loads, and mortality. Collectively, these findings suggest that both isolates are promising vaccine candidates and provide essential data for future PoRVA prevention and control strategies.
{"title":"Assessment of genetic diversity and pathogenicity of porcine rotavirus A, and immunogenicity of a bivalent inactivated vaccine in southern China","authors":"Guangli Hu , Zhiqing Zhao , Liguo Gao , Rui Geng , Shengjin Liu , Hao Zhang , Yongchang Cao , Hanqin Shen , Chunyi Xue","doi":"10.1016/j.vetmic.2026.110893","DOIUrl":"10.1016/j.vetmic.2026.110893","url":null,"abstract":"<div><div>Porcine group A rotavirus (PoRVA) is a widespread enteric pathogen that causes severe diarrheal outbreaks in swine herds, leading to considerable economic losses in China’s pig farming industry. From 2022–2024, a systematic surveillance was conducted across southern China, during which 5425 diarrheic samples were collected to assess the epidemiology of PoRVA. The results showed that PoRVA infections peaked in winter and spring, with monthly positivity rates ranging from 36 % to 68 % in southern regions. Genotyping of 103 VP4/VP7 sequences revealed the predominant VP7 genotypes G5 (43.69 %), G4 (23.39 %), and G9 (15.53 %), as well as the major VP4 genotypes P[13] (68.93 %), P[6] (10.68 %), and P[23] (9.71 %). Two PoRVA strains were successfully isolated from positive intestinal samples collected in Guangdong and Jiangsu provinces, designated RVA/Pig/China/JS/2024/G9P[23] (JS2024) and RVA/Pig/China/GD/2024/G5P[13] (GD2024), respectively. Experimental infection demonstrated that both isolates caused severe watery diarrhea in 3-day-old colostrum-deprived piglets, resulting in mortality rates of 40 % (2/5) for JS2024 and 20 % (1/5) for GD2024. A bivalent inactivated vaccine prepared with the two isolates (10^8 TCID<sub>50</sub>/mL per antigen, administered twice at a 14-day interval) elicited robust neutralizing antibody responses against both G5 and G9 genotypes. Furthermore, maternal immunization with the bivalent vaccine in pregnant sows resulted in efficient transfer of maternal antibodies to neonatal piglets. Piglets born to vaccinated sows exhibited significantly higher pre-challenge neutralizing antibody titers, developed only mild clinical diarrhea following JS2024 or GD2024 challenge, displayed substantially reduced fecal viral shedding, and showed 100 % survival, in contrast to unvaccinated litters, which experienced severe diarrhea, high viral loads, and mortality. Collectively, these findings suggest that both isolates are promising vaccine candidates and provide essential data for future PoRVA prevention and control strategies.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110893"},"PeriodicalIF":2.7,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079313","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}
Pub Date : 2026-01-22DOI: 10.1016/j.vetmic.2026.110894
Raúl Fernández-Delgado , Rafael Gutiérrez-López , David Romero-Trancón , Pilar Aguilera-Sepúlveda , Desirée Dafouz-Bustos , Núria Busquets , Miguel Ángel Jiménez-Clavero , Francisco Llorente
West Nile virus (WNV) is one of the most widespread emerging arboviruses in the world. Recently, Europe has undergone a significant increase in WNV incidence and geographic extension, with two genetic lineages, lineage 1 and lineage 2, actively circulating. In Spain, lineage 1 was first identified in 2007, and subsequently spread through the southwest and central regions of the country. Since 2010, it has affected both horses and humans (mainly in southern Spain), including two large human outbreaks of WNV meningoencephalitis in 2020 and 2024. Lineage 2 was first identified in Catalonia (northeastern Spain) in 2017, spreading through this region, primarily affecting birds, but with low incidence in humans and horses. In this study, the infectivity and disease severity of Spanish WNV isolates obtained between 2007 and 2020, representing both the southwestern and northeastern variants, was examined by in vivo inoculation in mice, with the aim of inferring their pathogenicity in mammalian hosts. The results demonstrated that the analysed isolates from northeastern Spain consistently induced lower virulence profiles in mice compared to the isolates from the southwest. Differences in mortality rates, median survival times, and survival curves, the latter being statistically significant allowed the classification of northeastern (lineage 2) and southwestern (lineage 1) Spanish isolates as moderately virulent and highly virulent, respectively. In vitro replication assays did not reveal significant differences between the Spanish isolates. Although biological and genetic differences between species could limit the extrapolation of mice data to other mammals, our findings are consistent with virulence patterns observed in humans and horses in the geographic regions where the examined isolates originated.
{"title":"Pathogenicity assessment of Spanish West Nile virus isolates of lineages 1 and 2 in a Swiss mouse model","authors":"Raúl Fernández-Delgado , Rafael Gutiérrez-López , David Romero-Trancón , Pilar Aguilera-Sepúlveda , Desirée Dafouz-Bustos , Núria Busquets , Miguel Ángel Jiménez-Clavero , Francisco Llorente","doi":"10.1016/j.vetmic.2026.110894","DOIUrl":"10.1016/j.vetmic.2026.110894","url":null,"abstract":"<div><div>West Nile virus (WNV) is one of the most widespread emerging arboviruses in the world. Recently, Europe has undergone a significant increase in WNV incidence and geographic extension, with two genetic lineages, lineage 1 and lineage 2, actively circulating. In Spain, lineage 1 was first identified in 2007, and subsequently spread through the southwest and central regions of the country. Since 2010, it has affected both horses and humans (mainly in southern Spain), including two large human outbreaks of WNV meningoencephalitis in 2020 and 2024. Lineage 2 was first identified in Catalonia (northeastern Spain) in 2017, spreading through this region, primarily affecting birds, but with low incidence in humans and horses. In this study, the infectivity and disease severity of Spanish WNV isolates obtained between 2007 and 2020, representing both the southwestern and northeastern variants, was examined by <em>in vivo</em> inoculation in mice, with the aim of inferring their pathogenicity in mammalian hosts. The results demonstrated that the analysed isolates from northeastern Spain consistently induced lower virulence profiles in mice compared to the isolates from the southwest. Differences in mortality rates, median survival times, and survival curves, the latter being statistically significant allowed the classification of northeastern (lineage 2) and southwestern (lineage 1) Spanish isolates as moderately virulent and highly virulent, respectively. <em>In vitro</em> replication assays did not reveal significant differences between the Spanish isolates. Although biological and genetic differences between species could limit the extrapolation of mice data to other mammals, our findings are consistent with virulence patterns observed in humans and horses in the geographic regions where the examined isolates originated.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110894"},"PeriodicalIF":2.7,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079297","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}
Pub Date : 2026-01-22DOI: 10.1016/j.vetmic.2026.110903
Yunzhe Kang , Xiuwen Yang , Rui Wang , Wenhui Zhu , Lulu Yao , Lijie Lv , Yongkun Du , Guoqing Zhuang , Aijun Sun
Marek’s disease virus (MDV), a highly oncogenic alphaherpesvirus of chickens, causes severe immunosuppression and fatal T-cell lymphomas. The UL24 gene is conserved among alphaherpesviruses and contributes to viral replication and pathogenesis in several members of this subfamily; however, its role in MDV remains undefined. Here, we constructed a UL24-deletion mutant (Md5BACΔUL24) and its repaired revertant (Md5BACΔUL24-Re) in the virulent Md5 strain using Red-mediated recombination. In vitro, UL24 deletion significantly impaired viral replication, as evidenced by smaller plaque size and reduced viral genome copies compared to parental and revertant viruses. In specific pathogen-free (SPF) chickens, UL24 deficiency markedly decreased viral loads in the spleen, prevented lymphoid organ atrophy, and abolished tumor development, indicating a profound attenuation of virulence. Bioinformatic analyses revealed a putative nuclear localization signal and a conserved PD-(D/E)XK endonuclease motif within MDV UL24, suggesting involvement in nuclear processes critical for replication. Collectively, these findings establish UL24 as a critical role of MDV replication and pathogenesis and represent a promising target for the rational design of attenuated or recombinant MDV vaccine vectors.
{"title":"UL24 deletion attenuates Marek's disease virus replication and pathogenicity","authors":"Yunzhe Kang , Xiuwen Yang , Rui Wang , Wenhui Zhu , Lulu Yao , Lijie Lv , Yongkun Du , Guoqing Zhuang , Aijun Sun","doi":"10.1016/j.vetmic.2026.110903","DOIUrl":"10.1016/j.vetmic.2026.110903","url":null,"abstract":"<div><div>Marek’s disease virus (MDV), a highly oncogenic alphaherpesvirus of chickens, causes severe immunosuppression and fatal T-cell lymphomas. The <em>UL24</em> gene is conserved among alphaherpesviruses and contributes to viral replication and pathogenesis in several members of this subfamily; however, its role in MDV remains undefined. Here, we constructed a <em>UL24</em>-deletion mutant (Md5BACΔUL24) and its repaired revertant (Md5BACΔUL24-Re) in the virulent Md5 strain using Red-mediated recombination. <em>In vitro</em>, <em>UL24</em> deletion significantly impaired viral replication, as evidenced by smaller plaque size and reduced viral genome copies compared to parental and revertant viruses. In specific pathogen-free (SPF) chickens, <em>UL24</em> deficiency markedly decreased viral loads in the spleen, prevented lymphoid organ atrophy, and abolished tumor development, indicating a profound attenuation of virulence. Bioinformatic analyses revealed a putative nuclear localization signal and a conserved PD-(D/E)XK endonuclease motif within MDV <em>UL24</em>, suggesting involvement in nuclear processes critical for replication. Collectively, these findings establish <em>UL24</em> as a critical role of MDV replication and pathogenesis and represent a promising target for the rational design of attenuated or recombinant MDV vaccine vectors.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110903"},"PeriodicalIF":2.7,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079314","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}
Pub Date : 2026-01-20DOI: 10.1016/j.vetmic.2026.110900
Lei-lei Yang , Min Sun , Wen-wen Zhang , Hai-yan Wang , Zi-long Cheng , Mao-jun Liu , Zhi-xin Feng , Wen-liang Li
The respiratory epithelium acts as the airway's first physical barrier against invading pathogens, mainly relying on mucociliary clearance (MCC) and apical junctional complexes (tight junctions/TJs and adherens junctions/AJs) for barrier function. Primary airway epithelial cells cultured in the air-liquid interface (ALI) system can well mimic these characteristics in vitro. This study established and characterized well-differentiated ALI-cultured goat airway epithelial cells (ALI-GAECs), and developed a CPIV3 infection model therein, verifying the apical infection and release of CPIV3 in ALI-GAECs. CPIV3 infection impaired the barrier function of ALI-GAECs, as reflected by decreased trans-epithelial electrical resistance (TEER), increased FITC-Dextran permeability, and reorganization of the ZO-1 and F-actin meshwork. Mechanistically, RT-qPCR and Western blot analyses demonstrated that CPIV3 downregulated major TJ proteins (ZO-1, occludin, claudin-1) while upregulated the expression of proinflammatory cytokines (TNF-α, IL-1β, IL-4, IL-6). The NF-κB signaling pathway, but not the MAPK pathways, was activated upon viral infection. Treatment with the NF-κB inhibitor BAY 11–7082 partially restored the expression of TJ proteins and proinflammatory cytokines. Collectively, the activation of the NF-κB pathway and subsequent production of proinflammatory cytokines is responsible for CPIV3-induced TJ disruption. In addition, the developed ALI-GAECs model provides a valuable in vitro tool for investigating the pathogenesis of CPIV3 and other caprine respiratory pathogens.
{"title":"Disruption of goat airway epithelial barrier function by caprine parainfluenza virus type 3 infection in an ALI model","authors":"Lei-lei Yang , Min Sun , Wen-wen Zhang , Hai-yan Wang , Zi-long Cheng , Mao-jun Liu , Zhi-xin Feng , Wen-liang Li","doi":"10.1016/j.vetmic.2026.110900","DOIUrl":"10.1016/j.vetmic.2026.110900","url":null,"abstract":"<div><div>The respiratory epithelium acts as the airway's first physical barrier against invading pathogens, mainly relying on mucociliary clearance (MCC) and apical junctional complexes (tight junctions/TJs and adherens junctions/AJs) for barrier function. Primary airway epithelial cells cultured in the air-liquid interface (ALI) system can well mimic these characteristics <em>in vitro</em>. This study established and characterized well-differentiated ALI-cultured goat airway epithelial cells (ALI-GAECs), and developed a CPIV3 infection model therein, verifying the apical infection and release of CPIV3 in ALI-GAECs. CPIV3 infection impaired the barrier function of ALI-GAECs, as reflected by decreased trans-epithelial electrical resistance (TEER), increased FITC-Dextran permeability, and reorganization of the ZO-1 and F-actin meshwork. Mechanistically, RT-qPCR and Western blot analyses demonstrated that CPIV3 downregulated major TJ proteins (ZO-1, occludin, claudin-1) while upregulated the expression of proinflammatory cytokines (TNF-α, IL-1β, IL-4, IL-6). The NF-κB signaling pathway, but not the MAPK pathways, was activated upon viral infection. Treatment with the NF-κB inhibitor BAY 11–7082 partially restored the expression of TJ proteins and proinflammatory cytokines. Collectively, the activation of the NF-κB pathway and subsequent production of proinflammatory cytokines is responsible for CPIV3-induced TJ disruption. In addition, the developed ALI-GAECs model provides a valuable <em>in vitro</em> tool for investigating the pathogenesis of CPIV3 and other caprine respiratory pathogens.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110900"},"PeriodicalIF":2.7,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038670","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}
Pub Date : 2026-01-20DOI: 10.1016/j.vetmic.2026.110897
Chathuri H. Rodrigo , Sathya N. Kulappu Arachchige , Sahar Zare , Rhys N. Bushell , Arif Anwar , Jiongrui Huang , Peter Scott , Amir H. Noormohammadi , Marc S. Marenda
The bacterium Ornithobacterium rhinotracheale causes upper respiratory tract infections (URTI) in commercial poultry worldwide. Efficient diagnostic and control of this emerging pathogen require accurate understanding of its classification, prevalence and distribution. The present study explores the genetic diversity of sixty-seven organisms presumptively identified as Ornithobacterium and recovered from chickens with URTIs in Australian free-range layer farms. Rep-PCR fingerprinting revealed wide diversity of isolates between and within farms and sites of infection. Forty representative isolates were sequenced entirely and compared to published genomes. Sequence alignments of the rpoB gene supported their classification into the genus Ornithobacterium, and 16S rRNA analysis revealed 98.08 % to 100 % identity with O. rhinotracheale type-strain DMS15997. However, most isolates gave non-interpretable profiles with the current Multi Locus Sequence Typing (MLST) scheme. Average Nucleotide Identity (ANI) analysis separated the dataset into four genetically divergent clusters. Most of the published O. rhinotracheale genomes, including DMS15997, belonged to the largest group, whereas the other clusters contained isolates with ANI values ranging from 84 % to 92 % against DMS15997, suggesting the presence of new species or sub-species. Pan-genome analysis was consistent with these observations, identifying only a small set of core genes (n = 254) in the dataset, while delineating distinct subsets of accessory proteins for each ANI cluster. Core single nucleotide polymorphism phylogeny confirmed further the substantial genetic diversity of the isolates. This study underlines the complex epidemiology and taxonomy of Ornithobacterium-associated URTIs in poultry farms, and is expected to improve diagnostic and control programs for this pathogen.
{"title":"Comparative genomics of Ornithobacterium spp. isolated from free range layer chickens with respiratory infections unveils marked genetic diversity and putative new species","authors":"Chathuri H. Rodrigo , Sathya N. Kulappu Arachchige , Sahar Zare , Rhys N. Bushell , Arif Anwar , Jiongrui Huang , Peter Scott , Amir H. Noormohammadi , Marc S. Marenda","doi":"10.1016/j.vetmic.2026.110897","DOIUrl":"10.1016/j.vetmic.2026.110897","url":null,"abstract":"<div><div>The bacterium <em>Ornithobacterium rhinotracheale</em> causes upper respiratory tract infections (URTI) in commercial poultry worldwide. Efficient diagnostic and control of this emerging pathogen require accurate understanding of its classification, prevalence and distribution. The present study explores the genetic diversity of sixty-seven organisms presumptively identified as <em>Ornithobacterium</em> and recovered from chickens with URTIs in Australian free-range layer farms. Rep-PCR fingerprinting revealed wide diversity of isolates between and within farms and sites of infection. Forty representative isolates were sequenced entirely and compared to published genomes. Sequence alignments of the <em>rpoB</em> gene supported their classification into the genus <em>Ornithobacterium</em>, and 16S rRNA analysis revealed 98.08 % to 100 % identity with <em>O. rhinotracheale</em> type-strain DMS15997. However, most isolates gave non-interpretable profiles with the current Multi Locus Sequence Typing (MLST) scheme. Average Nucleotide Identity (ANI) analysis separated the dataset into four genetically divergent clusters. Most of the published <em>O. rhinotracheale</em> genomes, including DMS15997, belonged to the largest group, whereas the other clusters contained isolates with ANI values ranging from 84 % to 92 % against DMS15997, suggesting the presence of new species or sub-species. Pan-genome analysis was consistent with these observations, identifying only a small set of core genes (n = 254) in the dataset, while delineating distinct subsets of accessory proteins for each ANI cluster. Core single nucleotide polymorphism phylogeny confirmed further the substantial genetic diversity of the isolates. This study underlines the complex epidemiology and taxonomy of <em>Ornithobacterium</em>-associated URTIs in poultry farms, and is expected to improve diagnostic and control programs for this pathogen.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110897"},"PeriodicalIF":2.7,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039139","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}
Pub Date : 2026-01-19DOI: 10.1016/j.vetmic.2026.110898
Tong Xu , Hanyu Li , Baoling Liu , Lei Zhao , Yangming Dai , Xin Wu , Siyuan Lai , Jian-Bo Huang , Ling Zhu , Zhi-Wen Xu
Pseudorabies virus (PRV), an emerging zoonotic alphaherpesvirus, can cause severe central nervous system (CNS) injury in non-natural hosts. Although mice are widely used for PRV neuropathogenesis studies, strain-dependent differences remain incompletely characterized. In this study, we established both intranasal and intramuscular PRV infection models in three commonly used mouse strains, KM, BALB/c, and C57BL/6, and performed comparative evaluations at early fixed post-infection timepoints as well as at moribund stages. After intranasal infection, C57BL/6 mice exhibited the highest absolute LD50 value among the three strains. Consistently, C57BL/6 mice showed the earliest onset of neurological symptoms, the fastest decline in survival, and significantly higher neurological deficit scores compared with KM and BALB/c mice. Viral load measurements at both early and moribund stages revealed significantly higher PRV replication in the brains of C57BL/6 mice, accompanied by more severe histopathological lesions. Moreover, C57BL/6 mice displayed markedly greater Evans blue extravasation and more pronounced downregulation of tight-junction proteins ZO-1 and occludin, indicating more extensive blood–brain barrier (BBB) disruption. Across all strains, intranasal inoculation induced stronger CNS pathology and BBB damage compared with intramuscular injection. Collectively, these findings demonstrate that C57BL/6 mice exhibit the highest susceptibility to PRV, with more severe neuropathology and BBB impairment at both early and terminal stages. These results provide important guidance for selecting appropriate mouse models for PRV-induced CNS injury research.
{"title":"Comparative analysis of PRV-induced neuropathology and blood–brain barrier disruption identifies C57BL/6 as the most susceptible mouse model","authors":"Tong Xu , Hanyu Li , Baoling Liu , Lei Zhao , Yangming Dai , Xin Wu , Siyuan Lai , Jian-Bo Huang , Ling Zhu , Zhi-Wen Xu","doi":"10.1016/j.vetmic.2026.110898","DOIUrl":"10.1016/j.vetmic.2026.110898","url":null,"abstract":"<div><div>Pseudorabies virus (PRV), an emerging zoonotic alphaherpesvirus, can cause severe central nervous system (CNS) injury in non-natural hosts. Although mice are widely used for PRV neuropathogenesis studies, strain-dependent differences remain incompletely characterized. In this study, we established both intranasal and intramuscular PRV infection models in three commonly used mouse strains, KM, BALB/c, and C57BL/6, and performed comparative evaluations at early fixed post-infection timepoints as well as at moribund stages. After intranasal infection, C57BL/6 mice exhibited the highest absolute LD<sub>50</sub> value among the three strains. Consistently, C57BL/6 mice showed the earliest onset of neurological symptoms, the fastest decline in survival, and significantly higher neurological deficit scores compared with KM and BALB/c mice. Viral load measurements at both early and moribund stages revealed significantly higher PRV replication in the brains of C57BL/6 mice, accompanied by more severe histopathological lesions. Moreover, C57BL/6 mice displayed markedly greater Evans blue extravasation and more pronounced downregulation of tight-junction proteins ZO-1 and occludin, indicating more extensive blood–brain barrier (BBB) disruption. Across all strains, intranasal inoculation induced stronger CNS pathology and BBB damage compared with intramuscular injection. Collectively, these findings demonstrate that C57BL/6 mice exhibit the highest susceptibility to PRV, with more severe neuropathology and BBB impairment at both early and terminal stages. These results provide important guidance for selecting appropriate mouse models for PRV-induced CNS injury research.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110898"},"PeriodicalIF":2.7,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146030938","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}
Pub Date : 2026-01-19DOI: 10.1016/j.vetmic.2026.110899
Chaolun Fu , Hongyan Gao , Yingchao Li, Chang Liu, Yuzhong Zhao, Youbo Li, Zhong Liu, Man Lu, Yang Shen, Yajing Xing, Yu Wang, Xiaotong Wu, Pingping Yang, Yihong Xiao
Macrophage surface molecules critically regulate inflammatory responses. Porcine reproductive and respiratory syndrome virus (PRRSV), an immunosuppressive pathogen with marked tropism for porcine alveolar macrophages, modulates host surface receptor expression to facilitate infection. Here, we screened the expression of immunoregulatory molecules during PRRSV infection and identified CD40 as the most significantly upregulated transcript. We demonstrated that the PRRSV nucleocapsid protein (N) enhances CD40 promoter activity, whereas nonstructural proteins Nsp1α, Nsp11, and Nsp12 suppress it. Mechanistically, protein N upregulated CD40 via the transcription factor ATF-2, while Nsp1α, Nsp11, and Nsp12 downregulated CD40 through AP-1. CD40 overexpression restricted PRRSV replication, suggesting its potential as a target for antiviral strategies.
{"title":"PRRSV nucleocapsid and nonstructural proteins dual-regulate CD40 expression via ATF-2 and AP-1 pathways","authors":"Chaolun Fu , Hongyan Gao , Yingchao Li, Chang Liu, Yuzhong Zhao, Youbo Li, Zhong Liu, Man Lu, Yang Shen, Yajing Xing, Yu Wang, Xiaotong Wu, Pingping Yang, Yihong Xiao","doi":"10.1016/j.vetmic.2026.110899","DOIUrl":"10.1016/j.vetmic.2026.110899","url":null,"abstract":"<div><div>Macrophage surface molecules critically regulate inflammatory responses. Porcine reproductive and respiratory syndrome virus (PRRSV), an immunosuppressive pathogen with marked tropism for porcine alveolar macrophages, modulates host surface receptor expression to facilitate infection. Here, we screened the expression of immunoregulatory molecules during PRRSV infection and identified CD40 as the most significantly upregulated transcript. We demonstrated that the PRRSV nucleocapsid protein (N) enhances CD40 promoter activity, whereas nonstructural proteins Nsp1α, Nsp11, and Nsp12 suppress it. Mechanistically, protein N upregulated CD40 via the transcription factor ATF-2, while Nsp1α, Nsp11, and Nsp12 downregulated CD40 through AP-1. CD40 overexpression restricted PRRSV replication, suggesting its potential as a target for antiviral strategies.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110899"},"PeriodicalIF":2.7,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146030980","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}
Persistence of detectable Ehrlichia canis DNA after a full course of doxycycline treatment remains poorly described. Highly sensitive molecular tools are essential for monitoring this phenomenon. This study aimed to monitor E. canis DNAemia in naturally infected dogs over a 60-day follow-up period using droplet digital PCR (ddPCR) and to compare its performance with TaqMan real-time PCR (qPCR). Forty-one seropositive dogs (identified by the IDEXX SNAP 4Dx Plus test) exhibiting clinical signs consistent with canine monocytic ehrlichiosis (CME) were enrolled as the Day 0 group. Follow-up samples were collected during recovery from partially overlapping cohorts at Days 30 (n = 21) and 60 (n = 14). At Day 0, ddPCR detected E. canis in 33 of 41 dogs (82.92 %), outperforming qPCR (25/41; 60.97 %). At Days 30 and 60, ddPCR detected E. canis DNA in 12 of 21 (57.14 %) and 5 of 14 (35.71 %) dogs, respectively, while qPCR detected only 2 of 21 (9.52 %) at Day 30 and none at Day 60. Quantification of bacterial loads showed a significant decline from a median of 2.28 DNA copies/µL at Day 0–0.067 copies/µL at Day 30 (P < 0.05), and 0.0614 copies/µL by Day 60 (P < 0.05). Dogs with hematocrit (Hct) levels below 25 % on Day 0 were significantly more likely to have ddPCR-positive results at Day 30 (P = 0.035), suggesting a potential association between severe anemia at diagnosis and persistent DNAemia. The high sensitivity of ddPCR revealed persistence of detectable E. canis DNA with very low bacterial loads. These prolonged bacterial DNAemia require further studies incorporating viability assays to clarify whether residual DNAemia reflects persistent viable infection or non-viable bacterial DNA.
{"title":"Longitudinal assessment of Ehrlichia canis bacterial load in naturally infected dogs using droplet digital PCR","authors":"Peeravit Sumpavong , Krittanut Kanittakul , Sarawan Kaewmongkol , Gunn Kaewmongkol","doi":"10.1016/j.vetmic.2026.110896","DOIUrl":"10.1016/j.vetmic.2026.110896","url":null,"abstract":"<div><div>Persistence of detectable <em>Ehrlichia canis</em> DNA after a full course of doxycycline treatment remains poorly described. Highly sensitive molecular tools are essential for monitoring this phenomenon. This study aimed to monitor <em>E. canis</em> DNAemia in naturally infected dogs over a 60-day follow-up period using droplet digital PCR (ddPCR) and to compare its performance with TaqMan real-time PCR (qPCR). Forty-one seropositive dogs (identified by the IDEXX SNAP 4Dx Plus test) exhibiting clinical signs consistent with canine monocytic ehrlichiosis (CME) were enrolled as the Day 0 group. Follow-up samples were collected during recovery from partially overlapping cohorts at Days 30 (n = 21) and 60 (n = 14). At Day 0, ddPCR detected <em>E. canis</em> in 33 of 41 dogs (82.92 %), outperforming qPCR (25/41; 60.97 %). At Days 30 and 60, ddPCR detected <em>E. canis</em> DNA in 12 of 21 (57.14 %) and 5 of 14 (35.71 %) dogs, respectively, while qPCR detected only 2 of 21 (9.52 %) at Day 30 and none at Day 60. Quantification of bacterial loads showed a significant decline from a median of 2.28 DNA copies/µL at Day 0–0.067 copies/µL at Day 30 (<em>P</em> < 0.05), and 0.0614 copies/µL by Day 60 (<em>P</em> < 0.05). Dogs with hematocrit (Hct) levels below 25 % on Day 0 were significantly more likely to have ddPCR-positive results at Day 30 (<em>P</em> = 0.035), suggesting a potential association between severe anemia at diagnosis and persistent DNAemia. The high sensitivity of ddPCR revealed persistence of detectable <em>E. canis</em> DNA with very low bacterial loads. These prolonged bacterial DNAemia require further studies incorporating viability assays to clarify whether residual DNAemia reflects persistent viable infection or non-viable bacterial DNA.</div></div>","PeriodicalId":23551,"journal":{"name":"Veterinary microbiology","volume":"314 ","pages":"Article 110896"},"PeriodicalIF":2.7,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146012500","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}
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