Transboundary and Emerging Diseases最新文献

The devastating impact of porcine epidemic diarrhea virus (PEDV) on the global swine industry underscores an urgent need for effective antiviral therapies. Drug repurposing presents a promising strategy to accelerate the development of such treatments. In this study, we screened a custom-designed library of 117 cholesterol-lowering compounds for anti-PEDV activity using a recombinant PEDV expressing enhanced green fluorescent protein (EGFP). Following two rounds of screening, four compounds exhibiting significant antiviral activity were identified. Among these, cetaben and digitonin displayed superior antiviral efficacy and higher selectivity indices. Subsequent dose-response analyses further confirmed that cetaben effectively suppresses viral replication in both classical and variant strains of PEDV. Time-of-addition assays revealed that cetaben exerts potent antiviral effects primarily at the preinfection stage by inhibiting viral internalization and syncytium formation. Notably, supplementation with exogenous cholesterol in infected cells completely abolished cetaben's antiviral activity and restored viral infectivity, demonstrating that its anti-PEDV mechanism is mediated through disruption of cellular cholesterol metabolism. Collectively, our findings identify cetaben, a cholesterol-lowering agent, as a novel broad-acting antiviral against PEDV with a host-targeted mechanism of action. This study establishes a foundation for developing antiviral strategies that target cholesterol metabolism to combat PEDV and related coronaviruses.

Since its first incursion in 2019, African swine fever (ASF) has remained a constant threat to the Vietnamese swine industry. The nationwide commercialization and implementation of live-attenuated vaccines (LAVs), alongside depopulation-repopulation efforts, necessitate a critical assessment of whether these strategies have driven inadvertent changes in circulating African swine fever virus (ASFV) strains. In this study, molecular surveillance of ASFV core genes was conducted in pigs from non-vaccinated farms across Central and Southern Vietnam, comparing strains before and after LAVs' introduction. The results confirmed spillover and ongoing field circulation of LAV-related strains and revealed a marked increase in genetic diversity, encompassing both vaccine-like and novel wild-type microvariants in the post-vaccine commercialization phase. Notably, these microvariants harbored non-synonymous single-nucleotide polymorphisms (SNPs) and large segmental deletions within the EP153R-EP402R gene, suggesting potential alterations in viral function. Most compellingly, a unique 15-AGACCAGCAACAAAC-nucleotide repeat in the E183L gene resulted in a five-amino-acid insertion (Arg-Pro-Ala-Thr-Asn) in the p54 protein, serving as a key marker for Vietnamese strains. Initial in silico analysis indicated that this novel p54 protein contained a longer α-helix structure, which could influence viral movement and interactions with host cells. Overall, these subtle yet significant genetic shifts imply that ASFV might be rapidly evolving intra-host under selective pressure from widespread immunization and/or diverse introduction sources during repopulation, potentially enabling it to evade the host immune system. This highlights the essential need for robust biosecurity protocols, stringent regulatory oversight of LAV deployment, and the required genetic surveillance. For diagnosis and management, the urgent development of reliable DIVA (Differentiating Infected and Vaccinated Animals) tools and real-time, adaptable molecular identification methods, coupled with a vaccination-tracking system, is necessary for accurate and sustained ASF control.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonosis of significant public health concern, maintained in complex multihost systems shaped by ecological, climatic, and anthropogenic drivers. In the Iberian Peninsula, changing land-use patterns and biodiversity loss may be reshaping host communities in ways that alter local transmission dynamics. We conducted a landscape-scale study across 18 sites, integrating serological surveillance of wild ungulates (n = 1461; 69.4% wild boar, 30.6% red deer) with camera-trap monitoring of mammalian communities, land cover analysis, and climatic data. To capture ecological drivers at different scales, we fitted two generalized linear mixed models (GLMMs): one including all sites to identify broad landscape-level predictors of exposure, and another restricted to endemic sites to evaluate fine-scale dynamics within established transmission foci. Overall, 44.5% of sampled individuals tested positive for CCHF virus (CCHFV) antibodies, with site-level seroprevalence ranging from 1.5% to 81.4%. Across all sites, seroprevalence was positively associated with red deer abundance, underscoring the potential role of red deer as key amplifying host, forest cover, and precipitation seasonality, while small ruminant presence was linked to reduced exposure risk. Within endemic areas, higher mammalian diversity and greater lagomorph abundance were negatively associated with exposure, whereas warmer temperatures promoted circulation. This pattern suggests that more balanced host communities can reduce the efficiency of pathogen transmission. Overall, this study highlights how community structure and environmental change jointly shape CCHFV ecology. The context-dependent nature of ecological drivers support integrated One Health strategies that conserve biodiversity, promote mixed grazing systems, and regulate wild ungulate populations to reduce CCHFV circulation in Mediterranean ecosystems undergoing socioecological transformation.

Transboundary animal diseases (TADs) are contagious diseases that significantly impact livestock health, public health and economic stability. In regions with frequent cross-border trade and transhumance involving camels, particularly the Middle East and Africa, TADs pose a heightened One Health risk due to their zoonotic potential and capacity to spread rapidly across national boundaries. This review synthesises current knowledge on TADs, with a focus on zoonotic pathogens affecting camels involved in cross-border movement, identifies geographical trends, and highlights research gaps to inform surveillance and control strategies. We conducted a comprehensive search across Ovid Medline, PubMed, Web of Science, Scopus, and Cochrane databases without time restrictions. Eligible studies were assessed for study quality and risk of bias using the Joanna Briggs Institute Critical Appraisal Checklist tools. Pooled prevalence estimates for TADs were calculated using random-effects models, with subgroup and meta-regression analyses to explore heterogeneity. Forty-five eligible articles were included, identifying 15 zoonotic TADs. Middle East respiratory syndrome (MERS) (34%), Rift Valley fever (RVF) (15%). The cross-border movements of camels contribute to the transnational spread of TADs, exacerbated by informal trade routes and nomadic pastoralism in arid regions. Our findings highlight the urgent need for harmonised surveillance and control strategies to mitigate the spread of zoonotic TADs through camel trade. Therefore, strengthening cross-border surveillance, harmonising diagnostic protocols, and integrating animal-human-environment data within a One Health framework is critical to mitigating zoonotic disease threats in these regions.

Muscovy duck reovirus (MDRV) causes substantial economic losses in the waterfowl industry, necessitating rapid and field-deployable diagnostic tools. In this study, we developed, for the first time, a lyophilized reagent-based reverse transcription recombinase-aided amplification (RT-RAA) assay targeting the σC gene of MDRV for point-of-care testing (POCT). The assay was optimized to operate at 39°C with a probe concentration of 100 nM. It achieved a detection limit of 1.03 × 10¹ copies/μL within 20 min, which is comparable to RT-quantitative polymerase chain reaction (qPCR) and superior to existing methods. It exhibited high specificity for MDRV with no cross-reactivity against other common waterfowl pathogens. Particularly, the assay was successfully lyophilized into a ready-to-use format, representing the first reported RT-RAA-based method for MDRV detection in such a format. The lyophilized reagents retained the key analytical performance characteristics without cold-chain dependance. When evaluated on 42 clinical samples, the lyophilized RT-RAA demonstrated 95.8% diagnostic sensitivity and 100% specificity compared to RT-qPCR, with almost perfect agreement (κ = 0.952). A visual readout using a portable blue light imager further enabled naked-eye interpretation without instrumentation. This robust, rapid, and field-deployable RT-RAA assay provides a practical solution for on-site MDRV surveillance, particularly in low-resource settings.

Accurate diagnosis of bovine tuberculosis (bTB) remains a critical challenge for disease control and eradication programs. While cell-mediated immune (CMI) response tests such as the comparative cervical intradermal tuberculin test (CCITT) are widely used, their sensitivity is limited, especially in later stages of infection. Antibody-based assays, such as enzyme-linked immunosorbent assays (ELISAs), may offer complementary detection and improve case identification. This study aimed to comparatively evaluate two indirect ELISA tests for the detection of antibodies against Mycobacterium bovis in naturally infected cattle from Southern Brazil. One ELISA test is in an experimental phase and uses a chimeric antigen comprising fragments of MPB70, MPB83, and ESAT-6 proteins. The second is a commercially available ELISA registered with the WOAH, based on MPB70 and MPB83 antigens. Serum samples were collected from 147 cattle across nine herds with known bTB epidemiological histories. All animals underwent CCITT, and a subset was subjected to post-mortem examination, culture, and nested-PCR. The experimental ELISA identified 16.6% of animals as seropositive, while the commercial ELISA identified 13.0%, both exceeding the 4.4% apparent prevalence detected by CCITT. Both ELISAs showed low sensitivity (<30%) when compared to culture or PCR-confirmed cases but were able to detect additional infected animals missed by CCITT. These findings support the use of serological tests as complementary tools to enhance bTB detection in cattle and inform surveillance and eradication strategies in endemic regions.

The World Health Organization has classified five species of Candida as pathogens of critical concern on its recent 'Fungal Pathogen Priority List'. Candida albicans is the most common species aetiologically associated with human and animal mucosa; however, we know almost nothing about the environmental survival and the transfer pathways of C. albicans in natural environments. Here, we have isolated C. albicans from the faeces of newly arrived migratory geese in two agricultural fields in Scotland (the United Kingdom). All 14 confirmed isolates were characterised in terms of their pathogenicity (in a Galleria larval infection model) and resistance to four classes of antifungal drugs. Multilocus sequence typing (MLST) was used to assess the relatedness of these isolates with C. albicans isolated from the faeces of sheep grazing in the same field. Finally, mesocosms were used to test whether C. albicans in geese faeces could persist and remain viable when incorporated into agricultural soils. All C. albicans isolates were virulent, and exhibited resistance to at least one of the four classes of antifungal drugs against which they were screened. Maximum likelihood phylogenetic analysis of MLST sequences revealed that C. albicans isolated from goose and sheep faeces were relatively conserved, although they did cluster independently on separate clades. C. albicans remained viable in common agricultural soils, and after 60 days, the concentrations of all three representative C. albicans isolates had only declined by one log. The unrestricted movement of migratory birds provides a significant opportunity for the widespread dissemination of pathogens. Although C. albicans is not generally considered to be zoonotic, its introduction into new environments and subsequent persistence in agricultural systems has the potential to facilitate transmission between animal species or humans. Therefore, it is critical that more emphasis be put on monitoring animal migration and the potential for cross-boundary movement of pathogens, particularly with climate change widening the geographic range for pathogen persistence.

Since 2020, clade 2.3.4.4b H5Nx high pathogenicity avian influenza viruses (HPAIVs) have consistently spread across continents, causing outbreaks worldwide. During the 2023-2024 (23/24) and 2024-2025 (24/25) winter seasons, clade 2.3.4.4b H5Nx HPAIVs caused multiple outbreaks on poultry farms and were detected in wild birds in South Korea. In this study, we present the emergence of clade 2.3.4.4b H5N1, H5N6, and H5N3 HPAIVs and examine the genetic characteristics of these viruses isolated from poultry and wild birds during the 23/24 and 24/25 winter seasons. In the 23/24 season, H5N6 and H5N1 HPAIVs caused outbreaks (poultry: 32, wild bird: 19), whereas in the 24/25 season, H5N3 and H5N1 HPAIVs were detected (poultry: 47 and wild bird: 43). Notably, a novel H5N3 HPAIV was isolated from northern pintail and identified as a reassortant virus distinct from the previously reported H5N3 HPAIV. Phylogenetic analysis of the hemagglutinin (HA) gene showed that viruses from both seasons were closely related to HPAIVs isolated in Eurasia. Gene constellation analysis identified two distinct genotypes of H5N1 viruses (23G0-G1) and one genotype of H5N6 virus (23G2) during the 23/24 season, with the latter being the dominant subtype in that period. In the 24/25 season, five distinct genotypes of H5N1 viruses (24G0-G4) were detected, with 24G1 being the major circulating genotype. Our results suggest that H5N6 HPAIVs appear to be circulating in East Asia alongside H5N1 viruses. Furthermore, in the 24/25 season, two genotypes of H5N1 viruses identified in South Korea were also detected in neighboring countries during the same period: 24G0 was detected in both Korea and Japan, while 24G1 was detected in Korea, Japan, and Mongolia. Therefore, a better understanding of the genetic characteristics of HPAIVs is important for inferring virus introduction and implementing effective control measures in the field.

Infectious bronchitis (IB) virus (IBV) remains a major pathogen threatening the poultry industry. Its rapid mutation and recombination continuously generate variants that disseminate worldwide. Between May 2024 and February 2025, 49 field strains were isolated from chickens vaccinated with live-attenuated IBV vaccines (H120, 4/91, or QXL87) in four Chinese provinces (Jiangsu, Anhui, Shandong, and Guangdong). Based on full-length S1 gene sequencing, all isolates were classified into genotype GI, including lineages GI-13 and GI-19. Phylogenetic analysis revealed that GI-19 (QX-type) comprised as much as 83.67%, with the nucleotide homology of the S1 gene to QXL87 varying from 93.4% to 99.8%. Recombination analysis indicated that the S1 genes of three isolates incorporate QXL87 and 4/91 genetic material, possibly arising from recombination between the QX-type and 4/91 vaccine strains. Virulence assessment in 1-day-old specific-pathogen-free (SPF) chickens demonstrated that four phylogenetically distant QX-type strains and one recombinant strain (with QXL87 as the major parent) induced varying degrees of tissue damage and mortality. Cross-neutralization assays demonstrated reduced antigenic relatedness between the circulating isolates and QXL87 vaccine strain. Structural mapping analysis further indicated that three amino acid mutations within the N-terminal domain (NTD) and two amino acid mutations in the C-terminal domain (CTD) of the S1 subunit alter its overall conformation, potentially leading to antigenic variation and facilitating immune evasion. Overall, these findings offer timely insights into the epidemiology and virulence heterogeneity of QX-IBV, providing valuable references for optimizing vaccine selection and development, as well as for preventing and controlling the disease.

Cetacean morbillivirus (CeMV) drives recurrent unusual-mortality events, yet surveillance is uneven where laboratory capacity is limited. We developed a portable reverse transcription-insulated isothermal PCR (RT-iiPCR) assay targeting a conserved phosphoprotein (P)-gene segment and evaluated analytical performance, tissue-level clinical sensitivity, and concordance with reverse transcription-quantitative PCR (RT-qPCR) under low-copy conditions that resemble challenging strandings. Using synthetic RNA, RT-iiPCR achieved 100% detection from 62,560 to 513 copies µL^-1, and probit analysis estimated a 95% limit of detection (LOD₉₅) of 139 copies µL^-1. Clinical sensitivity was assessed with two spiking regimes (RNA added after or before extraction) in cerebrum and lung. Singleplex RT-iiPCR maintained 100% positivity to approximately cycle threshold (Ct) 33 irrespective of spiking order, indicating that near-limit failures are governed by template scarcity rather than extraction loss. Duplex RT-iiPCR co-amplifying β2-microglobulin (B2M) provided process control with a slight sensitivity cost, sustaining perfect detection to ~Ct 30-31. Across low-copy panels, agreement with RT-qPCR was substantial (overall κ = 0.68-0.76) and very good in cerebrum (singleplex κ = 0.85; duplex κ = 0.87), while duplex lung showed lower concordance (κ = 0.55) driven solely by Ct >33 false-negative calls, with no false positives. The assay detected five lineages (dolphin morbillivirus [DMV], pilot whale morbillivirus [PWMV], beaked whale morbillivirus [BWMV], Guiana DMV [GDMV], and Fraser's DMV [FDMV]) in formalin-fixed, paraffin-embedded tissues archived up to 28 years, and sequence alignments indicate expected coverage of additional lineages. Lyophilized reagents, compact hardware, and a quick, simple workflow support deployment in hot, humid, resource-limited settings. A strain-agnostic, field-ready RT-iiPCR can underpin transboundary CeMV surveillance, enable rapid carcass triage and sequencing, and provide early warning where diagnostic gaps currently exist.