Transboundary and Emerging Diseases最新文献

The continuous emergence of circular Rep-encoding single-stranded (CRESS) DNA viruses across diverse hosts has been closely associated with the occurrence of severe diseases. Four circoviruses within the genus Circovirus have been identified in pigs, including porcine circovirus Type 1 (PCV1), PCV2, PCV3, PCV4, and PCV5. In late 2021, a large pig farm experienced an outbreak of reproductive disorders that were undiagnosed by standard tests. Subsequent viral metagenomic analysis of stillborn piglets identified a novel single-stranded circular DNA virus, designated porcine megalocircovirus (PMCV). PMCV has a large genome of 9426 nt and encodes nine open reading frames. Biochemical analyses of Rep confirm PMCV as a CRESS DNA virus. However, PMCV Rep showed low amino acid sequence identities to the four PCV species and several human CRESS DNA viruses, with the highest identity of 23.6% to PCV4 Rep. The genetic evolutionary tree indicates that PMCV belongs to an unknown family of the CRESS DNA viruses. The positive detection rate for PMCV in tested samples was 24% (30/125), while the positive rate regarding pig farms was 41.18% (14/34) in China. The emergence of PMCV warrants further investigation.

Feline calicivirus (FCV) is a major pathogen of upper respiratory tract diseases in cats, posing a significant threat to feline health. While current FCV preventive measures rely primarily on traditional vaccines, messenger RNA (mRNA) vaccines have emerged as a promising alternative, offering high efficacy, safety, rapid clinical development, and potential for fast, cost-efficient production. In this study, we designed a modified nucleotide sequence with a 124-amino acid deletion at a position in the region of the FCV-VP1 protein as an immunogen. The plasmid encoding the codon-optimized VP1 sequence was constructed, and VP1-mRNA was generated by in vitro transcription (IVT) and capping. After transfection into BHK-21 cells, immunofluorescence assay (IFA) and WB confirmed successful FCV-VP1 expression. Subsequently, the mRNA was encapsulated into lipid nanoparticles (LNPs) to prepare the LNP-VP1-mRNA vaccine. Characterization analysis revealed a uniform particle size distribution (polydispersity index [PDI] = 0.169) and a stable surface charge (zeta potential = -1.67 mV). A prime-boost immunization strategy was employed, which involved two intramuscular injections to immunize BALB/c mice or cats with the LNP-VP1-mRNA vaccine. ELISA analysis demonstrated that the vaccine elicited elevated levels of anti-FCV IgG and neutralizing antibodies in a dose-dependent manner, accompanied by the secretion of cytokines including IFN-β, IFN-γ, IL-4, and IL-6. Importantly, the VP1 mRNA vaccine provided complete protection against FCV challenge in cats, without the typical clinical signs and with a 100% survival rate. Our results indicate that the LNP-VP1-mRNA vaccine is a promising candidate for combating FCV infection.

Bandavirus dabieense severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne zoonotic virus that causes severe febrile illness and high fatality rates in people. SFTSV is endemic to East Asia, notably in the Republic of Korea (ROK), Japan, and China. Although several studies have reported SFTSV infections in domestic cats (Felis catus), reports of SFTSV in wild felids have been lacking. Previous serological analyses suggest exposure to SFTSV in various wildlife species. However, the clinical outcomes and the role of these animals in SFTSV transmission remain unclear. This study reports the first isolation and whole-genome analysis of SFTSV from a wild leopard cat (Prionailurus bengalensis euptilura) in the ROK. SFTSV was first detected in spleen tissue using real-time PCR, successfully isolated in Vero E6 cells, and confirmed with nested PCR and immunofluorescence assay (IFA). Phylogenetic analysis of whole-genome sequencing, including the L, M, and S segments, revealed that SFTSV from the leopard cat strain, belonging to sub-genotype B-1, showed 99.81%-99.94% nucleotide and 99.65%-99.95% of amino acid identity to previously reported strains from domestic cat and humans in the ROK. Notably, three distinct amino acid mutations, C12Y and H518Q in the M segment and F118S in the S segment, were unique to the leopard cat strain. While no remarkable gross pathological lesions were observed, the absence of other apparent causes of death suggests that SFTSV infection may have contributed. This study provides the first confirmed case of natural SFTSV infection with successful virus isolation from a wild leopard cat in the ROK. Our findings underscore the value of wild felids as ecological indicators of SFTSV circulation across diverse host within tick-borne transmission systems. These results highlight the importance of continued one health based surveillance to better understand the environmental and ecological contexts in which SFTSV persists.

Senecavirus A (SVA) is an emerging swine pathogen that causes vesicular disease, which presents clinically indistinguishable signs from other vesicular diseases. To enable differentiation of infected from vaccinated animals (DIVA), we developed a novel protein microarray for dual serological detection of antibodies against SVA structural (VP2-VP3-VP1) and non-structural (3AB-3C) proteins. The assay was based on two novel His-tagged tandem antigens, designed from immunodominant B-cell epitopes, which were expressed in Escherichia coli (E. coli), purified, and spotted onto a poly(dimethylsiloxane) (PDMS) substrate. Results were quantified by spot gray values to calculate sample-to-positive (S/P) ratios, with cut-off values set at S/P ≥0.651 for VP2-VP3-VP1 and S/P ≥0.607 for 3AB-3C. The microarray successfully differentiated inactivated-vaccine-immunized animals (positive only for VP2-VP3-VP1) from live SVA-challenged animals (positive for both antigens). In live SVA-challenged pigs, seroconversion to the structural protein antigen VP2-VP3-VP1 occurred 4 days earlier than the non-structural protein antigen 3AB-3C, identifying it as a sensitive early diagnostic marker. Clinical validation demonstrated 97.5% concordance with the virus neutralization test (VNT), confirming the microarray as a reliable, high-throughput tool for DIVA serological testing.

Major swine enteric viruses (SEVs), including porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), transmissible gastroenteritis virus (TGEV), swine acute diarrhea syndrome coronavirus (SADS-CoV), and porcine rotavirus (PoRV), cause severe gastrointestinal diseases in pigs, leading to huge economic losses to the swine industry around the world. In the absence of specific drugs and vaccines for controlling SEVs in the pig production, this review summarizes the inhibitory effects of natural products against these major porcine enteric viruses. Specifically, it focuses on recent studies regarding the anti-SEVS activities of traditional Chinese medicine (TCM) compound formulas, herbal extracts, pharmaceutical monomers, and natural metabolites. The review elaborates on how these natural products exert antiviral activities against SEVs, highlighting their potential as alternative or complementary agents for controlling porcine enteric viral infections. Overall, this work provides a comprehensive overview of the research progress in natural products against porcine enteric viruses and demonstrates the new strategies for medicine discovery, which will be helpful for further development of effective antiviral strategies in the swine industry.

Senecavirus A (SVA) is an emerging picornavirus causing vesicular disease indistinguishable from foot-and-mouth disease virus (FMDV). So far, there are no commercial vaccines and effective therapeutic drugs against SVA infection in China. Here, a library of 112 compounds were screened, and we found that phorbol myristate acetate plays an antagonistic role in the early stage of SVA infection. And phorbol 12-myristate 13-acetate (PMA) upregulates the expression of IKBKE, and activates IFN pathway and NF-κB signal. However, the PMA–mediated detrimental effect on SVA is reversed in IKBKE–deficient cells or when the NF-κB pathway blocked by BAY-117082, implying that IKBKE is the target for the antiviral effect of PMA. Additionally, PMA possesses antiviral effect on multiple RNA viruses, including porcine epidemic diarrhea virus (PEDV), porcine reproductive and respiratory syndrome virus (PRRSV), and encephalomyocarditis virus (EMCV). Overall, our findings offer that PMA inhibits SVA replication by activating IKBKE–mediated IFN pathway and NF-κB signal. And it might be a promising candidate for further broad-spectrum therapeutic development.

Reports of brucellosis in free-ranging cetaceans are increasing worldwide, particularly in the Mediterranean Sea. To enhance diagnostic accuracy and epidemiological understanding of cetacean brucellosis in the Western Mediterranean Sea, we analyzed bacteriological, serological, and molecular data from 30 cetaceans belonging to three different species stranded along the coast of the Valencian Community (Spain) between 2011 and 2021. Brucella ceti infection was confirmed by bacteriological isolation in 14 animals (46.7%) and by genus-specific qPCR in 15 cases (50%), with some discrepancies between methods. When feasible, serological analyses were performed using a commercial blocking ELISA (bELISA) and/or the Rose Bengal agglutination test (RBT). In the absence of ELISA tests properly validated for its use in marine mammals, we assessed the optimum dilution and cut-off of this ELISA kit using panels of gold-standard sera from culture-positive and brucellosis-free dolphins. From a pathological perspective, 12 infected animals showed moderate to severe meningoencephalitis or meningoencephalomyelitis with lymphoplasmacytic infiltration. Additionally, whole-genome sequencing (WGS) enabled the identification of two sequence types (STs), ST26 and ST49, indicating phylogenetic divergence. Our findings provide new insights into the phylogenetics of B. ceti and highlight the particular susceptibility of striped dolphins to this bacterium. The study also evidences the need for proper validation of the indirect diagnostic methods used for surveillance and seroepidemiological studies of brucellosis in marine mammals.

H5Nx Clade 2.3.4.4b high pathogenicity avian influenza viruses (HPAIVs) have been detected repeatedly in Great Britain (GB) since autumn 2020, with H5N1 dominating detections but with low level detection of H5N5 during 2025. Globally, these viruses have caused mass mortalities in captive and wild avian and mammalian populations, including terrestrial and marine mammals. H5N1 has been the dominant subtype, and whilst detections have overlapped temporally, occurrences have often been spatially distinct. Here, we report the detection of a mortality event in wild birds on the Norfolk coastline in the East of England, where H5N1 HPAIV was detected in five Great Black-backed Gulls (GBBGs; Larus marinus) and a Northern Fulmar (Fulmarus glacialis). Interestingly, at the same site, and as part of the same mortality event, a total of 17 GBBGs, one Herring Gull (Larus argentatus), one Atlantic Puffin (Fratercula arctica) and one Northern Fulmar tested positive for H5N5 HPAIV. Additionally, H5N5 was also detected in 17 co-located Grey Seal carcases (Halichoerus grypus). The H5N1 HPAIV from an infected bird belonged to genotype DI.2, closely related to contemporaneous detections in GB wild birds and poultry. In contrast, all H5N5 HPAIVs from birds and seals were Genotype I with a 22-amino acid stalk deletion in neuraminidase (NA) and the 627K polymorphism in PB2. This represents the first recorded instance in GB of two subtypes being detected within the same avian population at the same location. It is also the first mass detection of HPAIV H5N5 in mammals within GB. Potential infection mechanisms are discussed.

Newcastle disease (ND) virus (NDV) infection ranks among the most important poultry diseases globally. In Nigeria, ND remains a persistent menace to poultry production, marked by recurrent outbreaks. However, there is limited understanding of the evolutionary changes and transmission dynamics of the virus in the region. A molecular epidemiological study was conducted to elucidate the evolutionary and transmission patterns of NDV in Nigeria. Phylogenetic analysis of seven NDV isolates from cases recorded between 2023 and 2024 in four Northeastern states exhibited genetic diversity and formed distinct clusters that correspond to the prevailing subgenotype XIV.2. The maximum clade credibility (MCC) tree suggests sustained local circulation of the dominant NDV lineage, likely preceded by an international introduction from Southeast Asia. The fusion genes of the Nigerian genotype XIV and another important genotype XVII are mainly under negative selection, but codons 516 (XIV) and 114 (XVII) consistently show positive selection. The Nextstrain analysis reveals ongoing local evolution and genetic diversity of NDV in West Africa, and Central Nigeria acting as a key transmission hub, with evidence of reintroductions from neighboring countries. These findings have implications for NDV control and prevention strategies in Nigeria, highlighting the need for enhanced NDV surveillance, transboundary transmission control, and development of a vaccine tailored to the circulating NDV genotypes. The study also contributes to the understanding of regional spread pattern of NDV and informs evidence-based policies for mitigating the impact of the disease on poultry production.

Animal-origin influenza A virus (IAV) is a perennial candidate for causing the next pandemic. With high risk for interspecies IAV transmission but limited resources for surveillance, particularly in rural areas of low- and middle-income countries (LMICs) such as Laos, there is a need to develop targeted, risk-based strategies for early detection of novel IAVs that may emerge in pigs. We conducted (1) a cross-sectional survey to characterise pig producer types, management practices and pig movement patterns; (2) sampling among pigs in slaughterhouses to quantify IAV seroprevalence and infection; and (3) within- and between-herd disease modelling exploring the relative importance of farm type for the IAV epidemiology. Overall, 31.3% (100/319) of sera and 1.4% (7/515) of nasal swab samples from pigs tested positive for IAV antibodies (ELISA) and viral RNA (PCR detection of IAV M-gene), respectively. Most pigs sampled were exotic breeds and supplied by commercial farms. Using hierarchical Bayesian logistic regression models, seropositivity was significantly higher among exotic breeds compared with local breeds and higher among pigs originating from provinces outside of our study area. Stochastic, individual-based models of within- and between-herd transmission were developed and calibrated for five pig producer types using the cross-sectional data from 202 study participants. The modelling results suggested sustained IAV transmission between farms was unlikely unless the probability of local transmission, independent of pig movement, was relatively high, and the initial infection was seeded in areas with higher densities of smallholders. Between-herd IAV transmission was only sustained in scenarios where persistently infected commercial farms were present to continuously seed infection among the pig smallholder network. Together, these factors underscore risks associated with livestock intensification in commercial and smallholder productions. A larger study is warranted to fully characterise the interprovincial pig movement and evaluate IAV transmission within Laos to inform the national surveillance strategy.