Feline calicivirus (FCV) is a common pathogen causing upper respiratory tract disease in domestic cats. Nonetheless, its threat and genetic features in endangered wild felids remain poorly understood. In this study, a novel FCV strain from a captive South China tiger (Panthera tigris amoyensis) was isolated, designated as FCV LYH1224. Viral RNA was detected in multiple tissues of the deceased tiger, including the heart, liver, spleen, lungs, and kidneys, suggesting broad tissue tropism and FCV contributed substantially to the fatal outcome. In vitro growth kinetics showed that the virus replicates efficiently in Crandell-Rees feline kidney (CRFK) cells. Whole-genome sequencing and phylogenetic analysis indicated that it was classified as genotype II (GII) and exhibited unique evolutionary lineages. Within GII, it clusters closely with the previously reported tiger-derived strain FCV-YH/16 but exhibits an independent branch in the VP1 gene tree, suggesting complex genetic variation among FCV strains from diverse wildlife origins. Sequence identity analysis indicated that FCV LYH1224 was genetically distant from vaccine strains F9 and 2280, with whole-genome nucleotide identity of 76.6% and 77.0%, respectively. Notably, the VP1-E region displayed the lowest identity, with nucleotide identity of 68.1% and 66.7%, respectively. Analysis of key amino acid residues revealed distinct substitutions within the neutralizing epitope (aa 445-451) and common mutations at virulence-related positions 452A and 492I, which were absent in reference strains, suggesting potential antigenic diversity and host-specific adaptations. This study provides a comprehensive genomic characterization of FCV strain in South China tigers, highlighting the genetic diversity and distinctive antigenic properties observed in this isolate compared with existing strains. The considerable genetic divergence from vaccine strains emphasizes the importance of ongoing surveillance and the inclusion of wildlife-derived strains in vaccine development strategies.

Over the past decade, there has been an increase in reports of duck adenovirus type 3 (DAdV-3) infections in Muscovy ducks across various provinces in China, with mortality rates reaching as high as 43%. The rising incidence of this disease has led to significant economic losses for the waterfowl farming industry in China. In this study, a DAdV-3 strain was isolated from a Muscovy duck farm in Fujian province, which we designated as the FJNP-2021 strain, and further explored its pathogenicity and genetic characteristics. Pathogenicity analysis demonstrated that this FJNP-2021 strain induces characteristic pathological changes in Muscovy ducklings, exhibiting a broad tissue tropism, with the liver exhibiting the most severe lesions. The ultrastructural analysis revealed significant accumulation of lipid droplets and structurally disordered endoplasmic reticulum (ER) surrounding mitochondria in the hepatocytes of Muscovy ducklings postinfection. Moreover, in vivo DAdV-3 infection significantly downregulated ferroptosis suppressive genes (SLC7A11, GPX4, and FTH1) while upregulating proferroptotic genes TP53 and CHAC1. Our study provides dual ultrastructural morphology and molecular evidence that DAdV-3-induced hepatic lipid metabolism disorder triggers ferroptosis, thereby exacerbating hepatocyte injury. Phylogenetic analysis revealed that the complete genome sequence of the FJNP-2021 strain exhibited 92.3% identity with the representative strain GR from France, which was clustered in a different evolutionary lineage. Furthermore, the FJNP-2021 strain was grouped within the same lineage as domestic DAdV-3 strains, consistent with the genetic characteristics of the predominant epidemic strains of DAdV-3 in China. Notably, the Fiber1 genes of the Chinese DAdV-3 isolates formed two distinct subclades, and the Fiber1 gene of the FJNP-2021 strain clustered within the major subclade. In conclusion, this study analyzed the pathogenicity and genetic characteristics of all available DAdV-3 strains, enriching our understanding of the genomic diversity of Chinese isolates from 2014 to 2024 and providing a basis for further studies on DAdV-3 evolution and pathogenesis.

Porcine reproductive and respiratory syndrome (PRRS) remains one of the most economically significant viral diseases affecting the global swine industry, and currently available commercial vaccines provide only limited protection against circulating PRRS virus (PRRSV) strains. Therefore, alternative vaccination strategies are urgently needed to enhance protection against PRRSV infection. In this study, selected antigenic regions derived from the PRRSV structural proteins GP3, GP4, GP5, and M were incorporated into a β-annulus peptide-based nanoparticle scaffold derived from tomato bushy stunt virus (TBSV), and the resulting construct was further fused with the immunostimulatory molecule OX40L. The resulting OX40L-β-MEs protein formed nanoscale particles and was evaluated for immunogenicity and protective efficacy in piglets. Immunization with the OX40L-β-MEs nanoparticle vaccine induced measurable PRRSV-specific humoral responses and cellular immune-related responses in piglets. Following the challenge with the NADC30-like PRRSV strain GX-3264, piglets in the OX40L-β-MEs group showed shorter fever duration, reduced serum viremia and lung viral loads, and milder pulmonary lesions compared with PBS controls. In summary, these findings demonstrate that the β-annulus-based nanoparticle formulation can induce measurable immune responses and provide partial protection against NADC30-like PRRSV challenge, supporting further evaluation of this strategy for PRRSV vaccine development.

Pseudorabies virus (PRV), an important member of the Alphaherpesvirinae subfamily, shares high evolutionary homology with other members of the same subfamily, including human herpes simplex virus (HSV) and varicella-zoster virus (VZV). However, significant differences exist among them in terms of host range, pathogenicity, and immune evasion strategies. This review systematically compares the roles of PRV, HSV type 1 (HSV-1), and VZV in modulating host innate immune responses, encompassing the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling, RIG-I-like receptor (RLR) signaling, NOD-like receptor (NLR) signaling, Toll-like receptor (TLR) signaling, Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, apoptosis, and autophagy. By summarizing and comparing the interactions of these three viruses with the host innate immune response, this review aims to provide a theoretical reference for understanding the conserved and unique mechanisms of immune evasion among alphaherpesviruses, and to offer insights for the development of novel antiviral strategies.

Dirofilaria repens is a zoonotic parasite expanding across Europe due to climate change. We hypothesised that in this process, the Carpathian Basin has a facilitating effect. Using 426 georeferenced European cases, the probability of infection occurrence was determined in relation to climatic factors, surface water availability, regional social deprivation, and stray dog population density. To analyse the potential impacts of ecological and social factors (deprivation and stray dog population density), the MaxEnt algorithm, and spatial Empirical Bayes smoothing and bivariate local indicators of spatial association (BiLISA) index calculation were employed, respectively. MaxEnt analysis revealed that the mean warmest month temperature (MWMT; 22.8-25.1°C), winter mean minimum temperature (>-2.1°C), and summer precipitation (28.6-231 mm) have the strongest impact on the probability of the parasite's occurrence in Europe. Social factors have significance in the eastern Balkans and the Carpathian Basin, but not in Western Europe. The Carpathian Basin appears to be a hotspot, similar to Mediterranean coastal areas. Furthermore, the Danube Valley acts as an ecological corridor for subtropical vector-borne parasites. Our findings confirm that summer warmth is the primary ecological driver of the parasite's range expansion, which is facilitated by the Carpathian Basin due to climatic and socioeconomic conditions.

Brucellosis is an important zoonosis affecting public health and livestock production in Southeast Asia, but its regional epidemiology remains incompletely characterized. In this study, PubMed, Embase, Web of Science, and Scopus were searched for primary studies from the 11 Southeast Asian countries that reported serological findings, molecular detection, bacterial isolation, or Brucella species identification in human or animal populations. Publicly available PubMLST records were also analyzed using the 1764-locus Brucella core-genome multilocus sequence typing scheme. Across the eligible studies, reported crude seropositivity proportions ranged from 0.72% to 5.40% in humans and from 0.24% to 8.83% in animals. Molecular evidence included PCR positivity rates of 3.36% in goat vaginal swabs from Thailand and 39.2% in a selected mixed-livestock population from Indonesia, together with the identification of Brucella melitensis, B. abortus, and B. suis in several Southeast Asian countries. These findings provide epidemiological evidence of brucellosis in several countries. cgMLST analysis of the 24 available profiles from Malaysia and Thailand revealed close genetic relatedness among several isolates. Malaysian and Thai B. melitensis isolates differed by fewer than 11 alleles within the main cluster and by 41-81 alleles relative to isolates from India and the United Kingdom. Two Thai B. abortus isolates differed at only one locus and by 68-150 alleles from isolates from Bangladesh, India, and Bolivia, whereas five Malaysian B. suis isolates differed by 7-78 alleles, indicating limited genetic diversity within the Malaysian cluster. Additional genomic and epidemiological data are needed to determine whether genetically similar isolates are epidemiologically linked. Brucellosis appears endemic in parts of Southeast Asia, but important gaps in published data remain. Integrated One Health surveillance is needed to improve regional risk assessment and control.

Zoonotic tuberculosis (zTB) includes human tuberculosis caused by animal-associated Mycobacterium species, Mycobacterium bovis (M. bovis) being the major cause of zTB. This systematic review and meta-analysis was conducted to estimate the pooled burden of human M. bovis infection and describe the genetic diversity of M. bovis isolated from humans in the Middle East and North Africa (MENA) region. A literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Embase, and Google Scholar, followed by manual screening of additional references. The literature used for this paper were published between 2000 and 2025. A random-effects meta-analysis was used to estimate the pooled prevalence of human M. bovis infection. Heterogeneity was assessed using the I[2] statistic, while sensitivity analysis and Egger's regression test were used to assess the robustness of the findings and potential small-study effects, respectively. Totally, 27 studies from 10 MENA countries involving 6224 participants and 154 M. bovis-infected cases were included. The pooled prevalence of human M. bovis infection was 3% (95% CI: 2%-4%), with substantial heterogeneity (I[2] = 73.9%). The pooled prevalence was 4% in North Africa and 3% in the Middle East (p = 0.408). The individual study did not have an effect on the pooled prevalence as the leave-one-out sensitivity analysis did not change the pooled prevalence. The funnel plot showed some visual asymmetry, while Egger's regression test did not provide statistical evidence of small-study effects (p = 0.852). The M. bovis isolated from humans in MENA region were classified under European 1 (Eu1) and European 2 (Eu2) clonal complexes. In conclusion, the review highlighted the significance of M. bovis infection in humans in the MENA region, although there is a shortage of epidemiological data from more than 50% of the countries of the region. The isolation of Eu1 and Eu2 M. bovis clonal complexes from human M. bovis isolates suggested the importation was infected from Europe, which further transmitted the strains to humans. Strengthening of a One Health approach-based surveillance and molecular epidemiological studies in all MENA countries would contribute to the control of M. bovis in animals and humans in the region.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an emerging enteric coronavirus that causes severe diarrhea and high mortality in neonatal piglets. Its broad host range, tropism for human-origin cells, and limited vaccine availability underscore the importance of defining viral determinants of pathogenicity. The accessory protein ORF3 has been linked to CoV virulence, but its role in SADS-CoV infection in vivo and its impact on maternally transferred protection have not been fully established. Here, we used reverse genetics to generate rSADS-ΔORF3/GFP, a recombinant virus with ORF3 replaced by GFP, and compared it with parental rSADS-CoV in suckling BALB/c mice. ORF3 depletion markedly attenuated disease and reduced viral RNA burdens across tissues relative to parental rSADS-CoV. Because maternally derived immunity is critical to protection against swine enteric CoV infection in newborn animals, we further evaluated whether rSADS-ΔORF3/GFP, as a potential live attenuated vaccine (LAV), could elicit maternal protection transferred from inoculated dams to their offspring. Compared with parental rSADS-CoV, rSADS-ΔORF3/GFP induced lower maternal neutralizing antibody titers and provided less robust protection in challenged offspring. Nevertheless, offspring from rSADS-ΔORF3/GFP-inoculated dams showed improved survival, weight gain, milder intestinal pathology, and lower tissue viral RNA burdens than offspring from DMEM-inoculated dams, indicating retained protective immunogenicity. Together, these findings support a contribution of ORF3 to SADS-CoV virulence and demonstrate that ORF3 depletion yields an attenuated virus that retains partial maternally mediated protective efficacy. The residual immunogenicity of rSADS-ΔORF3/GFP, combined with its reduced virulence, supports its further evaluation as a LAV candidate.

Since the 1980s, highly pathogenic and hepatotropic Lagovirus species have significantly impacted rabbit populations, including Rabbit Haemorrhagic Disease Virus (RHDV, genotype GI.1), its variant RHDVa (genotype GI.1a), and RHDV type 2 (RHDV2, genotype GI.2). Non-pathogenic Lagovirus strains such as Rabbit Calicivirus (RCV, genotypes GI.3 and GI.4), which mainly replicate in the gastrointestinal tract, have also been identified. Recombination between pathogenic and non-pathogenic strains, particularly at the junction between non-structural (NS) and structural genome regions, is a major driver of the emergence of new variant strains. In the context of the widespread and predominant circulation of RHDV2, we analysed 51 RHDVa strains collected from domestic rabbit farms across Italy between 2013 and 2023 to assess their genetic and antigenic variability. Phylogenetic analyses were performed using full and partial genome sequences, and antigenic characterisation was conducted using a panel of RHDVa-specific monoclonal antibodies (MAbs). Phylogenetic analysis showed no evidence of recombination involving the Italian RHDVa strains. Nucleotide and amino acid identities with the reference strain RHDVa_Pv97 ranged from 95% to 98% and 97%-99%, respectively, confirming high genetic stability. The antigenic study indicated overall stability, consistent with the genetic results, but the few mutants found allowed us to map at least two epitopes located on the outer loops of the VP60 protein, which constituted a large part of the virus surface. In particular, the substitution at position N414S leads to the loss of MAb 2B4 binding to the RHDV/Italy/FG2014_1 strain, and the N348S mutation, which is present in five strains, results in the acquisition of binding to the MAb 2A10. Despite the global predominance of RHDV2, RHDVa persists to be detected sporadically in various Italian regions, especially within commercial rabbit farms. Continuous molecular and antigenic monitoring of Lagovirus strains remains essential to detect potential co-circulation and recombination events that could lead to the emergence of novel strains with distinct genomic and antigenic traits.

Free-roaming dogs (FRDs) pose a persistent challenge to canine rabies elimination in low- and middle-income countries, as conventional vaccination strategies often struggle to reach this population, which increases the risk of dog bites, rabies virus exposure and traffic accidents and complicates rabies control efforts. We conducted cross-sectional surveys in Nigeria and Sierra Leone and fitted country-specific probabilistic models to identify factors associated with FRD ownership. The proportion of FRDs was higher in Sierra Leone (78.7%; 95% CI: 77.1-80.3) than in Nigeria (58.5%; 95% CI: 58.2-61.2). In both countries, significant interactions between locality (urban versus rural), education level, access to veterinary services and dog vaccination status influenced FRD ownership. The probability of FRD ownership was higher among respondents with no formal education, particularly those living in rural areas with no access, or uncertain access, to veterinary services. In Nigeria, FRD ownership increased with household poverty. In Sierra Leone, it was highest in low-density rural areas, declined sharply with increasing population density and decreased with distance from roads. The interaction between literacy and primary education was associated with reduced FRD ownership, although neither variable was significant when considered independently. In both countries, owners with good rabies knowledge and owners of indigenous, rather than mixed-breed, dogs were more likely to own FRDs. Spatial variation in FRD ownership was evident in both countries. In Nigeria, dog owners in Kaduna and the Federal Capital Territory (FCT) were less likely to own FRDs than those in Anambra and Enugu. In Sierra Leone, the probability of FRD ownership was substantially higher in northern than in southern regions. Based on human-to-dog ratios of 2.77:1 in Nigeria and 2.75:1 in Sierra Leone, we estimated dog populations of ~11.7-12.7 million and 666,000, respectively. These findings highlight the need for targeted public education on responsible dog ownership and effective dog management, alongside community-level interventions in rural and other high-risk areas to reduce FRD populations. The resulting population estimates provide valuable evidence for planning and implementing mass canine rabies vaccination programs in both countries.

Emerging viral zoonoses-infections caused by viruses that cross the species barrier from animal reservoirs into human populations-account for the majority of emerging infectious disease (EID) events and now constitute a defining threat to global health security. Over the past decade the tempo of these spillovers has increased, propelled by land-use change, agricultural intensification, wildlife trade, and climate change, while reverse zoonosis-the transmission of human pathogens back into animal populations-has created novel animal reservoirs capable of seeding future outbreaks. Against this backdrop, we systematically reviewed and meta-analyzed epidemiological evidence on emerging viral zoonoses from January 2016 through June 2026, searching five bibliographic databases and synthesizing 312 included studies. Annual high-consequence spillover events increased by 4.98% (95% CI 3.22%-6.76%), and the decade saw five Public Health Emergency of International Concern (PHEIC) declarations, alongside other high-consequence spillovers such as the 2026 Bundibugyo virus outbreak (case fatality rate [CFR] 30.9%) and the expansion of H5N1 highly pathogenic avian influenza into dairy cattle. Bat-origin viruses exhibited the highest pooled CFR (29.86%), whereas primate-origin viruses demonstrated greater transmissibility, supporting a virulence-transmissibility trade-off. Land-use change emerged as the dominant anthropogenic driver, increasing zoonotic host diversity by 18%-72%. White-tailed deer SARS-CoV-2 seroprevalence reached 32.7% (95% CI 21.4%-46.1%), with confirmed deer-to-human spillback. Nonpharmaceutical interventions (NPIs) collectively reduced the effective reproduction number by up to 82%, and prevention-oriented One Health strategies yielded returns exceeding 1100% on investment. Viral zoonoses are accelerating under anthropogenic pressure, and upstream prevention with integrated One Health surveillance represents the most cost-effective pandemic preparedness strategy.

Peste des petits ruminants (PPR) is a highly contagious transboundary viral disease of small ruminants caused by the PPR virus (PPRV). Despite Ethiopia's goal of eradicating PPR by 2027 through a risk-based vaccination strategy, the disease remains endemic, with 554 outbreaks reported nationwide. This cross-sectional study was conducted in the North Gondar Zone, Ethiopia, between June 2024 and February 2025 to evaluate antibody responses in vaccinated small ruminants and estimate PPRV seroprevalence in unvaccinated flocks. A multistage cluster sampling design was used to select the study sites, while individual animals were selected using a haphazard sampling approach to approximate random sampling. A total of 600 serum samples were collected, including 300 from vaccinated and 300 from unvaccinated small ruminants; samples from vaccinated animals were obtained ~28 days postvaccination. All samples were tested for anti-PPRV antibodies using competitive enzyme-linked immunosorbent assay (c-ELISA). Overall individual-level seropositivity in the vaccinated population was 75%, comprising 75.73% in sheep and 72.1% in goats, serving as a proxy measure of flock immunity. In unvaccinated animals, PPRV seroprevalence was 14.33% (95% confidence interval [CI]: 10.6%-18.82%). Multivariable logistic regression identified age and flock size as the main risk factors influencing seropositivity. Adult animals were 2.89 times as likely to be seropositive as young animals (95% CI: 1.17-7.15; p = 0.022), and animals in medium-sized flocks were more likely to test positive than those in small flocks (AOR = 2.26; 95% CI: 1.11-4.63; p = 0.026). No significant differences were observed across districts, species, sex, production systems, newly introduced animals, or animal movement (p > 0.05). The observed seropositivity was slightly below the commonly used 80% population immunity target associated with reducing transmission under the PPR eradication framework. The detection of PPRV antibodies in unvaccinated animals indicates previous exposure to PPRV and highlights the need for strengthened surveillance to assess whether active virus circulation persists in the area. To achieve effective control and eventual eradication of PPR, intensified vaccination programs combined with active surveillance are needed. Furthermore, refining vaccination strategies in alignment with global and national eradication plans is essential to establish PPR-free zones in these districts.

Epizootic hemorrhagic disease (EHD) virus (EHDV) is a vector-borne virus transmitted by Culicoides midges that infects domestic and wild ruminants. EHDV causes high mortality in white-tailed deer (WTD) and oral lesions mimicking foot and mouth disease (FMD) in cattle. Small ruminants (e.g., domestic sheep, domestic goats) seroconvert but do not typically develop disease. In 2021, ~2100 WTD deaths were attributed to EHD in New York (NY) State. That same year, an EHD outbreak at a NY dairy resulted in a foreign animal disease (FAD) investigation to rule out FMD, and EHDV was detected in a captive bison herd in NY. In response to the EHD outbreak affecting wildlife, agricultural, and exhibition animals, serum samples from cattle, sheep, and goats submitted to the Cornell University College of Veterinary Medicine Animal Health Diagnostic Center (AHDC) were tested for EHDV antibodies. The samples tested in our surveillance study included samples collected during and after Culicoides vector activity (July-January) over three seasons from 2022 to 2025. A total of 5698 samples comprising 4874 cattle and 824 small ruminants were tested using the agar gel immunodiffusion assay (AGID). Season 1 had 0.6% seroprevalence (10/1719), season 2 had 0.7% seroprevalence (15/2021), season 3 had 0.5% seroprevalence (9/1958) with an overall seroprevalence of 0.6%. Neutralizing antibody (NA) titers were determined on all AGID positive samples for EHDV serotypes 1, 2, and 6. There were 20 samples positive for EHDV serotype 2 (NA titers from 1:40 to ≥ 1:1280); 11 samples positive for EHDV serotype 6 (NA titers from 1:10 to 1:640); and three animals with cross-reaction amongst serotypes. Of the 34 positive samples, 31 were from cattle and 3 were from sheep. Nineteen samples were from counties with large numbers of WTD deaths attributed to EHDV in 2021 or counties with cases of EHDV in cattle. This data indicates that EHDV serotypes 2 and 6 subclinically infected a small number of domestic ruminants in NY from 2022 to 2025.

Several animal species, including horses and pigs, can be infected with Japanese encephalitis virus (JEV). Feral pigs (Sus scrofa) are considered an effective amplifying host for JEV in natural habitats. In this study, 265 dried blood spots were collected from feral pigs in four selected North Queensland local government areas, and antibodies against JEV were detected using a competitive enzyme-linked immunosorbent assay (cELISA). The results showed that 26.4% (70/265) of the feral pigs had antibodies specific to JEV. We found a significant difference in the seroprevalence of JEV in the Wet Tropics (p < 0.05), compared to the Dry Tropics region of North Queensland. The results indicate that feral pigs in North Queensland have been exposed to JEV, suggesting that they may play an important role as an amplifying host. These findings may inform the planning of mitigation measures through a multisectoral One Health approach.

Recently, the identification of novel reassortants of infectious bursal disease (IBD) virus (IBDV) was reported. Interestingly, these strains competed with the previously dominant A3B2 lineage, becoming the prevalent lineage in Poland and disseminating to other countries in Europe. However, the specific virulence properties that facilitate their spreading were not elucidated. In this study, we compared the pathogenesis of the A3B4 Bug/03 and A3B2 75/11 IBDV strains in specific-pathogen-free (SPF) chickens, integrating viral replication dynamics, tissue tropism, immunosuppressive effects and host transcriptional responses. Both strains replicated efficiently in lymphoid and non-lymphoid tissues, with peak viral loads in the bursa of Fabricius. While the A3B2 75/11 strain exhibited higher viral RNA levels at early time points, the A3B4 Bug/03 strain persisted longer in multiple tissues. Notably, the A3B4 Bug/03 strain induced earlier bursal atrophy despite comparable viral loads at 4 dpi, and was associated with heterogeneous growth performance, reflecting uneven flock development. Transcriptomic analysis revealed distinct host response profiles between strains. Infection with the A3B4 virus was characterised by the enrichment of metabolic and translational pathways, indicating cellular adaptation and metabolic reprogramming. In contrast, the A3B2 75/11 strain triggered a strong activation of immune and inflammatory pathways, including cytokine and chemokine signalling. Collectively, these findings demonstrate that IBDV pathogenicity is not solely determined by viral replication, but is critically shaped by host response mechanisms. The ability of A3B4 strains to modulate host pathways and persist in infected birds likely contributes to their epidemiological success and facilitates their continued spread in poultry populations.