Transboundary and Emerging Diseases最新文献

Pseudorabies virus (PRV) causes substantial economic losses in the global swine industry. Serological diagnosis plays a crucial role in its eradication. Here, we developed a competitive enzyme-linked immunosorbent assay (cELISA) to detect antibodies against PRV glycoprotein D (gD). First, the recombinant gD ectodomain was expressed and purified to immunize mice, resulting in the generation of a monoclonal antibody (mAb 1D11) that targets gD. Subsequently, this antibody was conjugated with horseradish peroxidase (HRP), serving as the competing reagent. The cELISA was optimized under ideal conditions. Furthermore, validation using 204 swine serum samples—comprising 110 PRV-positive and 94 PRV-negative samples—demonstrated a high sensitivity and specificity, with a cutoff value of 46.16% inhibition determined by receiver operating characteristic (ROC) analysis (area under the curve = 0.995). Importantly, no cross-reactivity was observed with antibodies against other tested swine viruses. Both intra- and inter-assay coefficients of variation were found to be less than 10%, confirming high reproducibility of the assay results. When compared to a commercial PRV glycoprotein B (gB) ELISA kit (IDEXX), our cELISA exhibited strong agreement with κ = 0.90. This robust, specific, and sensitive cELISA provides a reliable tool for large-scale monitoring of PRV antibodies.

Salmonella is one of the most prevalent foodborne and zoonotic pathogens threatening global public health and food safety. Salmonella enterica subspecies enterica serovar Abortusequi (S. Abortusequi) is frequently reported as the etiological agent of equine abortion, septicemia, and polyarthritis. Currently, comprehensive studies on the virulence traits, evolutionary dynamics, and genomic diversity of donkey S. Abortusequi are limited. In this study, we assessed the genomic epidemiology, antibiotic resistance, and pathogenic traits of a ST251 S. Abortusequi strain (XJP1), isolated from donkey, using the core genome single nucleotide polymorphism (cgSNP) phylogenetic analysis, core genome multilocus sequence typing (cgMLST), comparative genomic analysis, the antimicrobial susceptibility tests, and virulence assays. Our cgSNP and cgMLST analyses indicate that XJP1 is closely related to Salmonella enterica subspecies enterica strains isolated from humans, equines, donkeys, poultry, and associated with multiple serovars. Additionally, XJP1 exhibited a multidrug-resistant profile, showing resistance to seven antibiotics. In a mouse infection model, XJP1 showed significantly higher lethality compared to the XJS1 strain. Notably, XJP1 harbored a plasmid containing an IncFIB/IncFII incompatibility group replicon and carrying the spvBC operon, as well as the rck, TTSS, pefABCD, fdeC virulence genes, and gadX acid resistance transcriptional activators gene. Our findings suggest that this plasmid may be a critical virulence determinant in XJP1. In conclusion, our data on the epidemiology and pathogenicity of ST251 S. Abortusequi provide valuable insights into the genetic, virulence, and transmission dynamics of donkey Salmonella enterica, highlighting the need for attention to food safety measures and public health surveillance.

Japan experienced its largest outbreak of highly pathogenic avian influenza (HPAI) during the 2022–2023 season, with 84 cases on poultry farms and the culling of more than 17 million birds. Commercial layer farms were the most affected, with 58 cases caused by the H5N1 subtype of the HPAI virus. To identify the risk factors and support future outbreak preparedness, a case–control study was conducted. All 58 affected commercial layer farms were designated as case farms, whereas 26 unaffected farms located within a 5 km radius of the case farms served as control farms. Data were collected through structured interviews using a questionnaire for the control farms and from on-site investigation records for the case farms. For control farms, all poultry barns on the premises were included, whereas only the initially affected barns were analyzed in the case farms. Logistic regression using a generalized linear mixed model was performed to evaluate the associations between HPAI outbreaks and explanatory variables related to farm- and barn-level factors, such as farm characteristics, husbandry and hygiene practices, barn structure, and environmental factors, including wildlife presence. Farm location was included as a random effect. The analysis identified a large number of laying hens on the farm (≥100,000 birds) as a potential risk factor. In contrast, changing shoes at the barn entrance and changing shoes or avoiding the use of the back door were identified as potential protective factors. These findings provide evidence-based guidance for strengthening biosecurity measures and improving HPAI prevention strategies on poultry farms in Japan.

Canine distemper virus (CDV; Morbilivirus canis) is a morbillivirus with worldwide distribution. The virus belongs to the family Paramyxoviridae, which includes highly pathogenic viruses such as measles virus (MeV) (Measles virus) and rinderpest virus (Rinderpest morbillivirus). Canine distemper is primarily a disease in domestic dogs, but it has been described in terrestrial and aquatic wild mammals, demonstrating the ability of CDV to cross species barriers. Here, we describe a lethal CDV outbreak in free-ranging marmosets (Callithrix penicillata) in Brazil. The marmosets were captured during a targeted epidemiological surveillance program aimed at monitoring viral agents in wildlife in urban parks of Belo Horizonte, Minas Gerais, Brazil. Affected marmosets presented with neurological signs, and others were found dead in the same area. In this report, we detail the occurrence of the outbreak and describe clinical manifestations, gross and histopathological lesions, tissue distribution of the virus by immunohistochemistry (IHC) and molecular methods, and phylogenetic analyses of the virus. This study demonstrated that CDV can infect free-ranging black-tufted marmosets and lead to neurologic signs, cutaneous lesions, and death. Viral genomic sequences and antigens were detected in several organs, indicating a pantropic distribution of CDV in this neotropical primate species. Additionally, the marmosets were also tested for MeV and Lyssavirus, which yielded negative results. Coinfections with CDV and Callitrichinae gammaherpesvirus 3 were detected in three marmosets. The CDV sequences identified here were closely related to both South American sequences and Vero cell-adapted lineages. These findings have significant implications from a One Health perspective.

Porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and porcine rotavirus group A (PoRVA) are recognized as major enteric viral pathogens responsible for porcine viral diarrhea. These viruses exhibit similar clinical manifestations, including vomiting, diarrhea, and dehydration, which complicate differential diagnosis. Therefore, there is an urgent need for a highly sensitive and specific diagnostic method to differentiate these pathogens. In this study, we developed a TaqMan-based one-step quadruplex reverse transcription real-time PCR (RT-qPCR) assay for the simultaneous and differential detection of these four porcine diarrhea viruses. The standard curves demonstrated correlation coefficients (R²) exceeded 0.990 across a dynamic range of 10^7.5 – 10^2.5 TCID₅₀/mL, and amplification efficiency ranged from 90% to 110%. The limit of detection (LOD) were 10^1.5 TCID₅₀/mL. Specificity analysis showed no cross-reactivity with other related pathogens. The assay exhibited good repeatability, with coefficients of variation (CVs) ranging from 0.15% to 1.41% for intra-assay and 0.09% to 2.09% for inter-assay, respectively. Finally, this method was evaluated for its practicality in the field using 348 clinical fecal samples. The positive rates of PEDV, TGEV, PDCoV, and PoRVA were 43.68%, 0.57%, 26.44%, and 33.91%, respectively. Furthermore, the coinfection rates of PEDV/PDCoV, PEDV/PoRVA, PDCoV/PoRVA, and PEDV/PDCoV/PoRVA were14.37%, 13.51%, 2.01%, and 5.75%, respectively. Compared to singleplex RT-qPCR assays, the quadruplex method demonstrated agreement rates ranging from 99.41% to 100% in detecting these four viral pathogens. In conclusion, the developed quadruplex RT-qPCR assay offers a reliable, sensitive, and accurate tool for the identification of four causative agents of porcine viral diarrhea, making it suitable for clinical diagnosis, disease surveillance, and epidemiological studies.

Pasteurella multocida (P. multocida), a significant animal pathogen, causes swine pneumonia and atrophic rhinitis, primarily associated with serogroups A, D, and F. Although serogroups A and D are prevalent in pigs and well-established causes of these diseases, the pathogenicity and genomic characteristics of porcine serogroup F remain poorly characterized. Here, we isolated a virulent P. multocida strain—AH01, from pigs with fatal acute respiratory disease in Anhui, China. It was characterized as a capsular Type F, lipopolysaccharide (LPS) antigen Type L3 isolate of sequence type (ST) 9. To evaluate the pathogenicity of this strain, pigs were challenged intratracheally with AH01 (6 × 10⁹ CFU), inducing acute pyrexia, dyspnea, anorexia, and rapid mortality (≤12 h postinfection, hpi). PacBio SMRT (Single-Molecule Real Time) sequencing generated a complete 2.27-Mbp chromosome (40.3% GC content; 2058 CDSs). Annotation identified 254 potential virulence-associated genes, 47 different drug resistance phenotypes, and three genomic islands (GIs). Comparative genomics revealed a novel 16.7-kb specific region insertion encoding zonula occludens toxin (Zot) and general secretion pathway protein D (GspD), potentially facilitating epithelial barrier disruption. Furthermore, polymorphisms in LPS outer core biosynthesis genes natC and gatF were characterized across strains avian Pm70, porcine AH01, and HN07. Strain AH01 harbors a single-nucleotide deletion (natC position 760), causing a frameshift and premature stop. Both porcine strains AH01 and HN07 exhibited a 216-bp N-terminal extension in gatF compared to avian Pm70 strain, indicating host-specific or strain-dependent LPS biosynthetic divergence. Collectively, these findings provide critical insights into the pathogenicity and genomic basis of porcine-derived P. multocida serogroup F.

Peste des petits ruminants (PPRs) is an economically significant disease affecting small ruminants. Owing to its impact on livestock and rural livelihoods, Ethiopia joined the global PPR eradication program and implemented risk-based vaccination strategies in 2018. However, gaps remain in understanding the geographic distribution, seasonal trends, and impact of this disease. To address these gaps, a repeated cross-sectional study was conducted between September 2018 and August 2024 in the North Shewa Zone to confirm PPR outbreaks via rapid antigen detection methods, specifically the pen-side test and dipstick technique. In addition, a retrospective analysis was performed to assess the spatial and temporal distributions of outbreaks, along with associated morbidity, mortality, and case fatality rates. The results revealed 48 confirmed PPR outbreaks over 6 years, occurring in 15 out of 24 districts, with an average of 8 outbreaks annually and a 0.33 proportion of affected districts, indicating low and localized spread. A total of 192 clinical samples were collected from symptomatic sheep and goats, all of which tested positive for PPRV. In total, 6415 PPR cases were documented, with a morbidity rate of 0.72%, a mortality rate of 0.11% (951 deaths), and a case fatality rate of 14.82%. Kewet had the highest number of outbreaks (7), whereas Mojana-Wedera recorded the highest number of cases (2718). Seasonally, 60% of the outbreaks occurred during the long rainy season, leading to 4472 cases and a fatality rate of 16.79%. Yearly trends showed consistent patterns, with 2023 having the highest number of outbreaks (15) and 2021 having the fewest (5). The year 2024 had the highest number of cases (2706). Despite continued viral circulation, the low morbidity and mortality rates, relative to the high transmissibility and fatality rates of the PPR in naïve populations (infection rates of up to 100% and mortality rates of 10%–90%), reflect significant control progress. While PPR remains endemic in the North Shewa Zone, the reduced incidence and clinical impact indicate measurable advancements toward eradication. Nonetheless, recurrent outbreaks across seasons and districts necessitate sustained, adaptive interventions. The study recommends strengthening surveillance, enhancing postvaccination sero-monitoring, and optimizing vaccine allocation to accelerate eradication.

Porcine epidemic diarrhea (PED) virus (PEDV) is a highly contagious intestinal infection that primarily affects suckling pigs. The interaction about the innate immune evasion of PEDV in intestinal epithelium and microRNA (miRNA) remains unclear. A strain of PEDV belonging to the G2a genotype, designated FJND 2022, was successfully isolated and confirmed. Then, the miRNA profile in exosomes-derived from intestinal porcine epithelial cell line (IPEC) infected with PEDV FJND 2022 for 48 h was evaluated. In exosomes from PEDV-infected IPECs, 34 miRNAs showed differential expression relative to blank cells. A total of 7762 target genes of those differentially expressed miRNAs were forecast, and the miR-193a-5P and its target mRNA interleukin (IL)22 and porcine β-defensin 1 (pBD1) attracted our interest. After infection with PEDV for 48 h, the mRNA levels and protein levels of IL22 and pBD1 were both notably downregulated, while the mRNA level of miR-193a-5P was significantly decreased. When IPECs were pretreated with the mimic of miR-193a-5P and then infected with PEDV, the mRNA levels of IL22 and pBD1 were significantly increased while the viral load of PEDV was significantly reduced. However, siRNA-mediated knockdown of IL22 abrogated the capacity of miR-193a-5p mimic pretreatment to restore pBD1 expression. Furthermore, the inhibitor of miR-193a-5P was pretreated with IPECs infected with PEDV, resulting in a notable downregulation of IL22 and pBD1 expression, and a significant upregulation of the virus load of PEDV. Finally, we also found that the expression levels of IL22, pBD1, and miR-193a-5P were notably reduced in the small intestinal epithelium of suckling piglets infected with PEDV for 48 h. Therefore, in this study we reveal that PEDV downregulates the miR-193a-5P expression in the intestinal epithelium to evade the antivirus of IL22/pBD1, which provides new insights into PEDV molecular pathogenesis and immune evasion mechanisms.

Tick-borne viruses (TBVs) represent a serious risk to global public and animal health. Despite the remarkable species diversity of ticks documented in Urumqi and its adjacent regions of China, scientific investigations into TBVs in this ecologically significant area have been strikingly scarce. In this study, we conducted metagenomic sequencing on 752 Hyalomma asiaticum (H. asiaticum), including questing ticks from Wujiaqu and blood-feeding ticks collected from sheep and horses in the Changji area. A total of 11 different RNA viruses were detected, belonging to six viral families and some unclassified families, with double-stranded RNA viruses being the most prevalent (49.1%), including Totiviridae and Sedoreoviridae. Single-stranded RNA viruses accounted for 11.9% of the virome, encompassing Chuviridae, Flaviviridae, Rhabdoviridae, and Phenuiviridae. Notably, 39.0% of the viral sequences remained unclassified, highlighting a substantial reservoir of uncharacterized viral diversity. Genomic and phylogenetic characterizations were performed on six highly abundant viruses, including Bole tick virus 1, Mivirus boleense, Bole tick virus 4, Lonestar tick totivirus, Hubei toti-like virus 24, and a novel strain of Hulunbuir Totiv tick virus 1. However, their zoonotic potential requires further investigation. By integrating cytochrome c oxidase subunit Ⅰ (COI) gene-based tick species identification with viral metagenomics, this study provided a comprehensive assessment of tick species and TBVs diversity in Urumqi and its surrounding areas, China. These results provide new insights into both the genetic diversity of tick-borne RNA viruses and their phylogenetic connections, while also expanding knowledge about the geographical distribution patterns of these pathogens.

Bovine tuberculosis (TB), primarily caused by Mycobacterium bovis, is a chronic infectious disease of cattle with significant public health and economic implications due to its zoonotic potential and impact on livestock productivity. The control of the disease is hindered by complex epidemiological dynamics and the chronic, and often slow-progressing nature of the disease. The recurrent outbreaks of bovine TB in endemic areas are common and threaten the success of eradication programs. To address this issue, long-term reemergent outbreaks in Catalonia (Northeastern Spain) were retrospectively investigated in depth. In 2009, an outbreak caused by M. bovis spoligotype SB0120 was detected in four extensively managed cattle herds. Following intensive eradication measures, all herds recovered the officially TB-free status by 2012. In 2021, 9 years later, a new outbreak involving the same spoligotype was detected in three herds located in the same area, one of which had been affected in the previous outbreak. Extensive sampling of TB-positive slaughtered cattle and hunted wild ungulates was conducted. Whole genome sequencing (WGS) of M. bovis isolates from cattle affected in both outbreaks, as well as from two culture-positive wild boars was performed. Epidemiological and phylogenetic analyses were conducted to elucidate the origin and transmission dynamics of the outbreaks. The results revealed a long-term residual infection in the cattle herd that linked the first and second outbreaks. This herd was also the most likely source of transmission of M. bovis to wild boars. Since residual infections can jeopardize the final stages of the eradication in low-prevalence settings, thorough investigation of reemerging strains is essential for risk assessment and for guiding TB control decisions.