Transboundary and Emerging Diseases最新文献

Pseudorabies virus (PRV), a significant pathogen that infects various animals, including pigs, encodes multiple proteins that participate in host–pathogen interactions. This study investigates the mechanisms by which PRV evades host immune responses, with a particular focus on the role of the UL41 protein and its interactions with host factors. We found that PRV infection modulates the interferon (IFN) signaling pathway, suppressing the expression of IFN-β and downstream antiviral factors while upregulating IFN-α. However, the direct role of UL41 in IFN-α upregulation remains to be elucidated. The PRV UL41 protein was shown to directly target the JAK/STAT pathway, binding to specific motifs, such as the conserved sequences KUUUCY and CSDGGA, in the untranslated region (UTR) of key mRNAs and degrading them, thereby inhibiting IFN-I signal transduction. Simultaneously, the UL41 can interact with host proteins, such as poly(A) binding protein (PABPC1) and host restriction factor tripartite motif protein 21 (TRIM21). Additionally, we discovered an antagonistic relationship between PRV UL41 and TRIM21. TRIM21, acting as an E3 ubiquitin ligase, binds to UL41 through its SPRY/PRY domain and mediates the degradation of the protein via the K48-ubiquitin-proteasome pathway. This interaction modulates the JAK/STAT pathway, with TRIM21 counteracting the inhibitory effect of UL41. In addition, the residue F78 within PRV UL41 is crucial for modulating mRNA and protein binding and ribonuclease (RNase) function, facilitating interactions with target proteins such as PABPC1 and TRIM21, and inhibiting the JAK/STAT pathway. These findings enhance our understanding of PRV pathogenesis and provide potential targets for developing novel antiviral strategies.

High pathogenicity avian influenza (HPAI) is an acute infectious disease of poultry and wild birds that has been occurring worldwide and has been controlled in many countries by culling birds on farms with disease outbreaks. We compared the gross lesions observed in influenza A (H5Nx) virus-positive cases of chickens and ducks in South Korea between 2023 and 2025. A total of 49 outbreaks were identified, comprising 34 cases in chickens and 15 cases in ducks, with both H5N1 and H5N6 subtypes detected. The lesions observed most frequently in chickens included splenomegaly and splenic necrosis, followed by tracheal congestion and pancreatic necrosis. In ducks, tracheal congestion was the most common lesion, followed by pancreatic necrosis and splenomegaly; hemorrhage and/or necrosis were also observed in the liver, ovarian follicles, heart, and lungs. Gross lesions in poultry caused by the H5N1 virus during the 2024–2025 season were observed more frequently than those associated with H5N6 virus in 2023. HPAI cases were characterized by ≥2 HPAI-typical lesions, such as pancreatic necrosis, splenic necrosis, and ovarian follicular hemorrhage, or the presence of HPAI–associated lesions in ≥3 different organs, even in the absence of HPAI-typical lesions. Assessing gross lesions in HPAI cases is crucial for guiding immediate disease control measures, including imposing movement restrictions on suspected farms, while awaiting confirmation by genetic testing and sequencing.

Understanding the ecological niches and quantifying the disease burden of Babesia species is essential for efficient surveillance and control strategies. Through a systematic review of global distributions, we document all 250 identified Babesia species across 73 vector species, 224 animals, and humans. Babesia caballi infected the broadest range of tick species, while Babesia microti exhibited the highest prevalence in wildlife. Among 26 848 recorded human cases involving 10 Babesia species, >90% were attributed to Babesia microti and Babesia duncani. Using three machine learning algorithms, we evaluated ecological and vector-associated determinants governing the distributions of six predominant Babesia species. Our models predict B. bovis to have the most extensive geographic range. Critically, habitat suitability index (HSI) of vector ticks emerged as the primary driver of Babesia transmission risk. Enhanced awareness, diagnostic capacity, and surveillance are imperative in identified high-risk regions.

Corriparta virus (CORV), an arbovirus within the Orbivirus genus, exhibits a broad vertebrate host range but limited pathogenicity. In this study, we report the first isolation and characterization of a novel orbivirus genetically related to CORV, temporarily designed as novel duck orbivirus (NDORV), from Beijing ducks in Henan province, China, in 2024. Genomic characterization revealed that NDORV possesses a 10-segment double-stranded RNA (dsRNA) genome, consistent with the structural hallmarks of the Orbivirus genus, with a high genetic similarity to Parry’s Lagoon virus (PLV) and CORV. To evaluate its pathogenicity, specific pathogen-free (SPF) ducks were experimentally inoculated with NDORV. Gross pathological examination revealed splenomegaly and blood stasis as primary lesions, with no mortality observed. Histopathological analysis identified tissue damage in the spleen, lungs, heart, liver, and kidneys. The highest viral loads were observed in the spleen and lungs, peaking at 3 days postinoculation (dpi). This study provides the first comprehensive characterization of a novel orbivirus genetically akin to CORV isolated from ducks in China. These findings highlight the potential prevalence of NDORV in domestic duck populations and underscore the urgency of enhanced surveillance and research on CORV-related arboviruses.

Porcine deltacoronavirus (PDCoV) is an emerging enteric pathogen that causes substantial economic losses in the global swine industry. Although neutralizing antibodies (NAbs) are a key indicator of vaccine efficacy, their diagnostic concordance with IgG/IgA levels measured by indirect enzyme-linked immunosorbent assays (iELISAs) targeting major structural proteins has not been systematically evaluated. In this study, the full-length spike (S), S1 domain, and receptor-binding domains (RBD) from a highly virulent PDCoV strain were expressed in CHO cells. At the same time, the membrane (M) and nucleocapsid (N) proteins were produced in Escherichia coli (E. coli). Following initial reactivity screening via protein microarray, S, S1, RBD, and N were chosen to establish iELISAs for detecting IgG and IgA antibodies in serum and milk samples. Evaluating iELISAs’ specificity revealed cross-reactivity of anti-S IgA and anti-N IgA with porcine epidemic diarrhea virus (PEDV) antibody-positive sera. Analysis of 75 clinical pig serum samples, and 75 colostrum samples demonstrated that IgA-based iELISAs had superior diagnostic concordance with virus neutralization test (VNT) results than IgG-based iELISAs, with the S1-IgA iELISA showing the highest concordance (93.3%). Furthermore, IgA antibody levels correlated more strongly with neutralizing titers (NTs) than IgG. These findings validate the S1-IgA iELISA as a robust, high-throughput serological tool for assessing PDCoV immunity in pigs.

Swine enteric coronaviruses (SeCoVs) cause acute enteritis and high mortality in neonatal piglets, posing a significant threat to the swine industry. Injectable vaccines often fail to induce effective mucosal immunity, and their efficacy is further compromised by maternally derived antibodies. Oral and intranasal mucosal vaccines offer promising alternatives, enabling localized and durable protection. This review summarizes recent advances in mucosal vaccines against SeCoVs, focusing on antigen delivery platforms and mucosal immune activation. Novel antigen delivery platforms, including nanoparticles (NPs), hydrogels, engineered probiotics, recombinant viral vectors, and eukaryotic expression systems, have improved antigen stability and facilitated transport across the epithelium to mucosal inductive sites. Moreover, targeting strategies that focus on microfold cells (M cells) and dendritic cells (DCs) enhance antigen uptake and presentation. These delivery systems promote mucosal immune activation by inducing secretory IgA (sIgA), maintaining Th1/Th2 balance, and promoting the generation of T and B cells. In addition, the incorporation of adjuvants further strengthens these responses, resulting in more robust and durable protection. By synergistically integrating advanced mucosal vaccine delivery systems with rational adjuvant strategies, this review provides theoretical and practical perspectives for the development of safe, effective, and broadly protective mucosal vaccines targeting SeCoVs infections.

African swine fever (ASF) is one of the most threatening animal diseases for the global swine industry. Due to the high risk of ASF virus (ASFv) transmission via infected suid meat and derived products, Italy adopted specific risk mitigation measures during 2023 and 2024. Two targeted programs were established to implement these measures: one addressing the illegal domestic trade of wild boar meat and meat products and the second focusing on irregularities in food imports. In both programs, products with traceability irregularity and improper or missing labels were seized. ASFv detection by real-time PCR was conducted on all suid meat and derived products originating from illegal national trade, as well as on illegally imported products in which suid DNA was detected. While smuggled local products did not show any ASFv contamination, a large proportion of the illegally imported products tested positive for ASFv by real-time PCR. However, experimental infection tests conducted both in vitro and in vivo using samples that tested positive by real-time PCR, yielded negative results indicating that the virus was inactivated. These programs highlighted the existence of an illegal network responsible for smuggling suid meat and derived products into Italy. Although in vivo and in vitro testing excluded the presence of infectious virus in illegally imported products, the potential risk of transboundary transmission through illegal importation remains a significant concern, necessitating ongoing surveillance and stringent biosecurity measures.

Rotavirus B (RVB) is among the enteric pathogens that can cause gastroenteritis in humans and various animals. However, severe diarrhea in newborn piglets has rarely been reported to be linked to porcine RVB (PoRVB). From 2023 to 2024, outbreaks of newborn piglet diarrhea with 20%–50% morbidity and 4%–10% mortality occurred in three herds situated in Anhui, Liaoning, and Jilin provinces of China. Notably, all samples from these herds tested negative for porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), PoRVA and transmissible gastroenteritis virus (TGEV). To identify the causative pathogens of the severe diarrhea in newborn piglets, high-throughput sequencing (HTS) was performed on pooled and individual samples collected from each farm. The results revealed that there were 783,546–1,237,231 mammalian virus reads per pooled sample, with PoRVB being the overwhelmingly dominant virus. A high prevalence of PoRVB (83.3%–100%) was detected in all the affected farms, indicating the association between PoRVB strains and the outbreak of severe piglet diarrhea in the sampled farms. Analysis of de novo assembled whole genomes from individual samples revealed that the PoRVB strains AHLW1/2023, JLCG2/2024, and LNDC5/2024 exhibited 81.8%−95.6% nucleotide and 88.9%−99.0% amino acid sequence identities of all 11 gene segments when compared to the most similar reference PoRVB strains. The genotype constellation of AHLW1/2023 was assigned to G34-P[4]-I13-R4-C4-M7-A8-N10-T4-E4-H7, which differs from JLCG2/2024 by one genotype (R7) and from LNDC5/2024 by three genotypes (G16, R7, and M4). This study demonstrated that PoRVB is the primary etiological agent responsible for severe diarrheal outbreaks in newborn piglets. It also highlights the importance of conducting continuous surveillance to effectively control PoRVB infections.

African swine fever (ASF) is a highly lethal disease affecting domestic pigs and wild boars, caused by the ASF virus (ASFV), which has rapidly spread across Asia in recent years. In this region, most reported ASF cases involve domestic pigs, while cases in wild boars remain notably lower except in a few countries. However, factors such as the high population of wild boars, limited wildlife surveillance, and inadequate farm biosecurity suggest that the prevalence and transmission of ASFV between these hosts may be underestimated. Therefore, we used a simplified multicriteria approach (SMCA) to identify vulnerable areas (VAs) for ASFV infection and validated the resulting VA maps with chi-square tests using reported ASF cases. The spatial SMCA revealed that VAs for ASFV infection in domestic pigs are concentrated in eastern China, while high-risk zones for ASFV infection in wild boars span Russia, eastern China, and Southeast Asia. Sensitity analysis showed that the variables that most influenced the risk of ASFV infection in domestic pigs and wild boars were anthropogenic factors and distribution of wild boars, respectively. Additionally, we predicted areas with significant transmission potential between domestic pigs and wild boars. High-risk regions for interspecies transmission include eastern China, southwestern Korea, and southern Japan. This study offers a standardized method to assess ASFV infection risk across Asia by integrating environmental and anthropogenic factors rather than relying solely on reported outbreaks. The findings highlight potential high-risk regions, including those without detected outbreaks, to improve surveillance and early detection strategies.

Infectious bursal disease virus (IBDV) causes an acute, highly contagious and immunosuppressive disease in 3–5-week-old chicken, called infectious bursal disease (IBD). Current vaccines targeting the hypervariable VP2 gene fail to provide cross-protection against different IBDV strains, necessitating the development of novel diagnostic and preventive strategies that explore other candidate genes to ensure immune efficacy. Here, VP3, a conserved nucleocapsid protein of IBDV, was selected for further analysis. A prokaryotic expression vector, pET-32a-IBDV-VP3, was constructed, followed by expression and purification of the recombinant protein. Following the intraperitoneal injection of recombinant proteins into the mice, eight monoclonal antibodies (mAbs) were identified by hybridoma cell fusion, clone purification, and immunological assays. Among the mAbs, mAb 19D8 effectively neutralized IBDV infection during viral attachment and penetration. Antigenic epitopes of mAb 19D8 were identified using alanine-scanning mutagenesis. Our results showed that four amino acids, F20, K21, T23, and E25, located on an α-helix of the VP3, were the key amino acids recognized by 19D8. Homologous and structural analyses revealed that these sites were highly conserved across different IBDV strains from diverse regions. These findings provide crucial insights into the antigenicity of VP3 and underscore the potential of VP3 as a target for the development of broad-spectrum diagnostic tools and cross-protection vaccines against IBDV.