Search Results (3,430)

This study developed a dual-antigen enzyme-linked immunosorbent assay (ELISA) based on σB protein and genotype 5-specific σC protein of avian reovirus (ARV). First, σB and σC proteins were expressed and purified using recombinant technology. Through optimization of coating conditions, the optimal antigen combination was determined to be a mixture of the two proteins at a 1:3 molecular ratio (total concentration: 0.8 μg/mL). Key parameters of the indirect ELISA were optimized via checkerboard titration. Validation confirmed that the dual-antigen ELISA exhibited a sensitivity of 1:3200 against genotype 5 ARV-positive sera, with no cross-reactivity and a coefficient of variation of 2.9–8.6%, demonstrating excellent reproducibility. In application testing, the method specifically detected serum antibodies against genotype 5 ARV variant strains, achieving a 100% positive detection rate in experimental chickens within the first week post-challenge and effectively monitoring dynamic antibody changes in infected flocks. Furthermore, the detection rate for genotype 5-positive serum samples (100%) was significantly higher than that of a commercial kit (75%). This dual-antigen indirect ELISA overcomes the sensitivity limitations associated with conventional genotype 5 ARV detection methods and provides a reliable tool for epidemiological surveillance and infection monitoring. Full article

Solitary living is an evolutionarily widespread yet comparatively under-theorized social system, despite its occurrence across diverse animal taxa. Shrikes (family Laniidae) are small predatory passerines that combine raptorial behavior, strong territoriality, and predominantly solitary space use, making them a powerful model for examining the ecology and evolution of solitary living. Here, I synthesize published work on shrike behavioral ecology and explicitly link these traits to the costs and benefits of a solitary lifestyle. I argue that shrikes exemplify how solitary species can offset the absence of social buffering through cognitive innovation, finetuned habitat selection, and flexible yet tightly bounded sociality. I then compare shrike ecology to solitary mammals and reptiles, highlighting convergent patterns in resource dispersion, spatial memory, risk management, and juvenile dispersal. I further examine how anthropogenic pressures, such as habitat fragmentation, climatic instability, and urbanization, interact with solitary life histories and review evidence from management interventions in both European farmland and North American systems that demographic recovery is achievable but remains contingent on addressing broader land-use conflicts and sources of adult mortality. Finally, I outline five interconnected research priorities—spanning cognitive ecology, trophic interactions, movement ecology, genomics, and formal comparative analyses—that would move shrike research from its current observational foundation toward a more experimental, mechanistic, and phylogenetically informed programme. By reframing shrikes as a model taxon for solitary living, this review aims to integrate avian behavioral ecology into broader comparative frameworks of social organization, cognition, and resilience under global change. Full article

Avian infective endocarditis is an uncommon but severe disease that is typically diagnosed postmortem because of nonspecific clinical signs and rapid progression. In the present study, five broiler chickens (n = 5) from a commercial flock were examined with septicemia and lesions suggestive of endocarditis. This study reports the first molecularly confirmed and characterized case of valvular endocarditis associated with multidrug-resistant Vagococcus fluvialis in poultry and provides a comprehensive review of bacterial endocarditis in avian species. The case involved a broiler chicken that presented with sudden death and septicemic lesions, including vegetative valvular endocarditis, pericarditis, and multiorgan involvement. Bacterial isolates recovered from cardiac lesions were identified as V. fluvialis using MALDI-TOF mass spectrometry and confirmed by 16S rRNA gene sequencing. Antimicrobial susceptibility testing revealed a multidrug resistance profile, with resistance to several antimicrobial classes commonly used in poultry production. The literature review identified published studies describing avian infective endocarditis, which predominantly affects poultry and is caused mainly by Gram-positive bacteria, with clinical signs and necropsy findings largely overlapping across etiologies. These findings highlight the novelty of V. fluvialis as a potential etiological agent of avian infective endocarditis and underscores the diagnostic challenges associated with avian endocarditis, particularly when uncommon pathogens are involved, and underscore the importance of advanced identification methods for an accurate etiological determination. Collectively, the results of this study expand the spectrum of bacterial species associated with avian infective endocarditis and emphasize the relevance of antimicrobial resistance and improved diagnostic strategies in poultry health and disease surveillance. Full article

Autonomous traversal flight in unknown 3D environments remains challenging due to mapping bottlenecks and computational latency. Inspired by pigeons navigating cluttered forests through instantaneous visual perception rather than constructing global metric maps, this paper presents a pigeon-inspired depth-reasoning-driven decision framework for agile quadrotor traversal in unmapped spaces without explicit map construction. To ensure feasibility, we leverage a robust state estimation backbone enhanced by deep-learning-based feature matching, providing stable pose feedback under aggressive maneuvers. The core contribution is a pigeon-inspired depth-reasoning framework that translates raw sensory depth data into a hybrid optimization framework, integrating both hard safety constraints and soft geometric smoothness constraints, directly emulating the three avian mechanisms: gap selection via instantaneous depth gradients, path selection that minimizes posture changes, and a safety field driven by the looming effect. By bypassing time-consuming mapping and spatial discretization processes, the framework significantly reduces perception-to-control latency. Finally, validated via simulations and real-world experiments on a resource-constrained quadrotor platform, our map-less approach achieves superior decision frequencies and comparable safety margins to those of state-of-the-art map-based planners. This framework offers a practical, high-frequency solution for autonomous flight where computational resources and environmental knowledge are strictly limited. Full article

Pigeonpox is a significant infectious disease caused by Pigeonpox virus (PPV), which severely impacts the pigeon industry. Current control methods primarily rely on heterologous vaccines, such as those derived from avian poxviruses, but their protection is limited, creating an urgent need for the development of a specific vaccine. In this study, 720 samples collected from several regions of China between 2022 and 2023 were tested for PPV, followed by virus isolation, identification, and genetic evolutionary analysis. Based on these findings, complete genome sequencing and attenuation of the representative BJ-02 isolate were conducted, and the potential of this strain as a candidate for an attenuated vaccine was preliminarily evaluated. The survey showed PCR positive rates of 9.05%, 16.11%, and 12.50% in samples from Beijing, Guangdong, and Hainan, respectively. Six viral strains were isolated, all of which produced typical lesions on chorioallantoic membranes (CAM) and chicken embryo fibroblasts (CEF). Phylogenetic analysis based on the P4b gene revealed that the six viruses clustered within the same evolutionary branch, closely related to PPV and penguinpox virus strains from South Africa, India, and Taiwan, China. Complete genome sequencing of the BJ-02 strain showed its genomic structure to be similar to that of other fowlpox viruses, with some differences. After serial passage in CAM, PEF and CEF, the BJ-02 SD55 high-passage strain adapted well to in vitro culture, exhibited significantly reduced pathogenicity in chicken embryos and pigeons, and showed no reversion to virulence after five consecutive back-passages. Animal immunization tests demonstrated that the BJ-02 SD55 suspected attenuated strain induced specific antibodies and provided 100% protection against challenge with the virulent strain. In conclusion, PPV is widely prevalent in China. The BJ-02 strain, successfully isolated and attenuated through serial passage, demonstrates excellent immunogenicity and high safety, making it a promising candidate for a specific pigeonpox vaccine. Additionally, the complete genome characterization of BJ-02 contributes to the avian poxvirus genome database and provides critical data to support research on viral pathogenesis and the development of viral vector vaccines for avian and potentially mammalian species. Full article

As one of the busiest airports in East China, effective bird-strike prevention is of paramount importance for Hangzhou Xiaoshan International Airport. Ground-dwelling insects in airport grasslands serve as a critical food source for insectivorous birds, making the study of insect communities essential for understanding bird activity patterns and mitigating bird-strike risks from a food chain perspective. This study investigates the communities of insects, birds, and vegetation in the flight zone and clear zone of Hangzhou Xiaoshan International Airport. Based on monthly surveys conducted from January to December 2024, we analyzed insect community composition and diversity, assessed bird-strike risks, and examined correlations between insect and bird communities. The results recorded a total of 7744 birds belonging to 107 species, 43 families, and 15 orders in the flight zone and clear zone. Passeriformes was the most species-rich order, and resident birds dominated the avian community. Bird species richness and abundance peaked in spring and autumn. In the flight zone, 18 bird species (e.g., Hirundo rustica) were classified as highly hazardous (R ≥ 15, where R is the calculated risk index) or above. The vegetation survey identified Cynodon dactylon as the dominant plant species in the flight zone. Importantly, positive trends were observed between insectivorous birds and insect abundance, though correlations did not reach statistical significance. To reduce food availability for birds, we recommend stringent management of the grassland habitat in the flight zone, including targeted insect control measures. Given the airport’s location along the East Asian-Australasian Flyway, enhanced bird dispersal efforts should be implemented during peak migration seasons. This study provides a crucial ecological foundation for developing an integrated “vegetation–insect–bird” management strategy for bird-strike prevention at Hangzhou Xiaoshan International Airport and similar aviation hubs. Full article

Marek’s disease (MD), caused by pathogenic Marek’s disease virus serotype 1 (MDV-1), is one of the most important avian immunosuppressive and neoplastic diseases and has led to huge economic losses to the poultry industry worldwide. Rapid and accurate clinical diagnosis is of great significance for efficient control of the disease. Herein, we have established a multiplex PCR (mPCR) method to simply differentiate all of the three types of MDV, using five specific primers targeting to MDV-1 oncogene meq or MDV-2 and MDV-3/HVT gB genes. Simultaneously, it can detect any type of virulent or vaccine MDV strains in one PCR reaction, with amplicons of the short (S) and long (L)-meq of MDV-1 strains, and the gB of MDV-2 and HVT vaccine strains. Non-specific amplifications of avian leukosis virus (ALV), reticuloendotheliosis virus (REV), or fowl adenovirus virus 4 (FAdV-4) were not observed, indicating a good specificity of this method. A total of 522 clinical samples of tumor-bearing or suspected diseased birds collected from 30 poultry farms were detected. The results demonstrated that the newly developed mPCR method accurately detected and differentiated epidemic MDV-1 infections and vaccine strains, and provided nearly 100% consistency for detecting clinical wild-type infections compared with conventional PCR amplification of the meq gene. Collectively, our data has provided a highly efficient method for early differential diagnosis of MD clinical cases, virus identification and future evaluation of vaccination efficacy in healthy chicken flocks, which would be meaningful for efficient control of the disease. Full article

Avian trichomonosis is caused by protozoa of the genus Trichomonas, mainly Trichomonas gallinae, which infects the upper digestive tract of birds and is commonly associated with Columbiformes, the main reservoirs of the parasite. This study aimed to investigate the occurrence and genetic diversity of Trichomonas spp. in captive synanthropic birds from southeastern Brazil. Oropharyngeal swabs were collected from 281 birds belonging to 13 avian orders and analyzed using Diamond medium culture, Giemsa-stained smears, and molecular assays. Of the 262 samples submitted to culture analysis, 72 (27.48%) showed trophozoite-like structures under light microscopy. Molecular screening based on the ITS1–5.8S–ITS2 region detected Trichomonas DNA in 76 out of 267 samples with successful DNA extraction (28.46%), including 72 Columba livia domestica from Franca, one Coragyps atratus from Ribeirão Preto, and three rock doves from Jaboticabal. Among the ITS-positive samples, 67 (88.15%) amplified the Fe-hydrogenase gene, and 65 (85.5%) were also positive for the 18S rRNA gene. Only six samples (2.29%) exhibited structures compatible with Trichomonas spp. in Giemsa-stained smears. Phylogenetic analyses based on ITS sequences grouped the isolates into two clades within the Trichomonas gallinae complex. Greater genetic diversity was observed using Fe-hydrogenase and 18S rRNA markers, revealing multiple haplotypes and clades. Molecular assays, particularly PCR applied directly to oropharyngeal swabs, showed higher sensitivity for detecting and characterizing Trichomonas gallinae compared to culture and cytology. These findings highlight the high occurrence and genetic diversity of T. gallinae in captive synanthropic pigeons and reinforce the importance of molecular tools for epidemiological surveillance in wildlife facilities. Full article

Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b continues to circulate globally across wild birds, poultry, and an expanding range of mammalian hosts, highlighting the need for antiviral strategies that address the animal–environment–human interface. The influenza A polymerase acidic (PA) endonuclease, a key enzyme in viral transcription, represents a conserved antiviral target across host species. In this study, we present a computational prioritization framework integrating homology modeling, molecular docking, molecular dynamics simulations, and physicochemical filtering to identify candidate PA endonuclease inhibitors relevant to a One Health context. Homology models of contemporary H5N1 clade 2.3.4.4b PA sequences were constructed based on the crystallographic template 6FS8 and used for cross-host docking against a targeted ligand library. Docking analysis identified baloxavir, a reference inhibitor, and entecavir, a nucleoside analog, as compounds of interest, with entecavir demonstrating favorable binding behavior, particularly in the poultry-associated model. Molecular dynamics simulations of the poultry PA–entecavir complex indicated stable interaction over 170 ns, supported by low structural deviation and favorable binding free energy (ΔG ≈ −85 kJ/mol). Physicochemical profiling suggested that entecavir possesses properties such as high polarity and predicted aqueous solubility, which were considered within the translational filtering step of this computational workflow. However, these properties do not establish antiviral efficacy or practical suitability for field use. The study provides a structured framework for integrating cross-host structural analysis with basic translational considerations, supporting the identification of candidate compounds for further biochemical and virological evaluation within the context of H5N1 control. Full article

Birds serve as the primary natural reservoirs for avian influenza viruses (AIVs), harboring nearly all known AIV subtypes. The seasonal migratory movements of wild birds play a significant role in the transmission and dissemination of AIVs. Jianhu Lake in Dali, Yunnan Province, serves as a vital congregation point along avian migratory routes, providing an ideal habitat for birds. In this study, a total of 619 avian samples were collected from the Jianhu area, from which four H6N2 subtype AIV strains were successfully isolated. Among these, A/grey heron/Jianhu/JH-89/2024 (hereafter referred to as JH-89) and A/grey heron/Jianhu/JH-91/2024 (JH-91) were isolated from grey herons (Ardea cinerea); A/mareca penelope/Jianhu/JH-2-11/2025 (JH-2-11) from a Eurasian wigeon (Mareca penelope); and A/duck/Jianhu/JH-1-1/2025 (JH-1-1) from a domestic duck (Anas platyrhynchos domesticus). Genomic analyses revealed that these four H6N2 isolates belong to the Eurasian lineage, with all eight gene segments originating from complex reassortment events among diverse Asian isolates. In vitro assays demonstrated that the representative strain JH-2-11 replicated efficiently in various human- and animal-derived cell lines. In vivo infection models revealed that, without prior adaptation, the JH-2-11 strain successfully infected BALB/c mice, resulting in suppressed body weight gain and severe pathological lesions in the respiratory tract (nasal turbinates, trachea, and lungs), without causing mortality or extrapulmonary dissemination. Collectively, although these H6N2 viruses evolve primarily within avian hosts, they exhibit potential for mammalian adaptation and require continuous epidemiological monitoring. Full article

Pseudomonas aeruginosa is a common Gram-negative bacterium in hospital infections and one of the main pathogens causing opportunistic infections in humans. In recent years, the drug resistance of P. aeruginosa has become increasingly severe. Therefore, it is urgent to explore new targets for antibacterial therapy. In P. aeruginosa, iron is an essential element not only for cell growth but also for successful infection. Two siderophores are produced by P. aeruginosa: pyoverdine and pyochelin. They help P. aeruginosa to obtain iron and play an important role in interspecific competition, anti-oxidative stress, and virulence. Furthermore, siderophores have been used to design “Trojan horse” antibiotics. These antibiotic–siderophore conjugates enter the cytoplasm of P. aeruginosa via siderophore uptake systems for pyoverdine and pyochelin, releasing antibacterial substances and exerting corresponding effects against P. aeruginosa. This review discusses the synthesis, secretion, and uptake of siderophores in P. aeruginosa as well as the role of the “Trojan horse” strategy in treating P. aeruginosa infections. Full article

Multidrug-resistant (MDR) Salmonella enteritidis infections cause high mortality and devastating economic losses in poultry, pose severe threats to animal health and food safety, and create an urgent demand for effective antibiotic alternatives. Herein, we developed a cationic liposome-encapsulated bacteriophage endolysin Lys40 (designated Lys40-Lip), and systematically evaluated its therapeutic efficacy in a chick model challenged with Salmonella enteritidis strain S4. Recombinant Lys40 was encapsulated into cationic liposomes with an encapsulation efficiency (EE) of 34.83%. The resulting Lys40-Lip nanoparticles had a hydrodynamic diameter of 137.3 ± 4.1 nm, a high positive zeta potential of +42.5 ± 0.3 mV, and excellent stability, retaining 78.52% of its initial bactericidal activity after 56 days of storage at 4 °C. Following a three-day oral treatment in Salmonella enteritidis S4-infected chicks, Lys40-Lip significantly increased survival rates in a dose-dependent manner (72.22% to 88.89% for low-to-high dose vs. 44.44% in infected controls, p < 0.05) and reduced ileal Salmonella enteritidis S4 colonization by 28.8% compared to free Lys40. Histopathology revealed Lys40-Lip restored duodenal villus integrity and reduced jejunal and ileal inflammation. Serum cytokine analysis confirmed that Lys40-Lip effectively regulated the host inflammatory response, significantly downregulating the pro-inflammatory cytokines IL-1β and IL-6, and upregulating the anti-inflammatory cytokine IL-10. Crucially, liposomal encapsulation overcame the outer membrane barrier of Gram-negative bacteria via charge-driven fusion mediated by its high positive surface potential (+42.5 ± 0.3 mV), enabling targeted delivery of Lys40 without the need for EDTA or other outer membrane permeabilizers. Lys40-Lip significantly improved the therapeutic outcomes of avian salmonellosis via synergistic direct bactericidal activity, intestinal barrier protection and inflammatory response regulation, offering a promising nanotherapeutic strategy for the control of this disease in veterinary practice. Full article

Necrotizing enteritis (NE) is an important intestinal disease threatening the poultry farming industry, and the ban on antibiotic growth promoters has created an urgent demand for safe and effective NE vaccines. Recombinant attenuated Salmonella vectors (RASVs) administered orally can induce mucosal immune responses against delivered antigens, thus showing great potential to elicit protective immunity against NE. The EntB protein is a newly discovered putative enterotoxin of Clostridium perfringens (C. perfringens). Bioinformatic predictions in this study revealed that EntB contains nineteen potential antigenic epitopes, two functional domains (NlpC and YgiM), and interacts with ten proteins, supporting its potential as a target antigen for NE vaccines. To optimize the immunogenicity of EntB-based vaccines, we constructed a novel recombinant attenuated Salmonella Enteritidis (S. Enteritidis) vector rSC0169 harboring a rhamnose-regulated delayed attenuation system, which was then used to deliver EntB to generate the recombinant strain rSC0169(pS-EntB). This system enhanced the immunogenicity of the Salmonella vector rSC0169 and further elicited robust mucosal immune responses against EntB, as well as humoral and cellular immune responses. Compared with the control strain rSC0169(pS0018), rSC0169(pS-EntB) candidate vaccine strain significantly alleviated NE symptoms, increased the intestinal villus height/crypt depth (VH/CD) ratio, upregulated tight junction protein expression, and reduced excessive pro-inflammatory cytokine production. In conclusion, this study provides a promising NE candidate vaccine and offers a valuable strategy for developing vaccines against other intestinal bacterial diseases. Full article

Campylobacter jejuni is a major zoonotic pathogen that circulates among birds, livestock, humans, and environmental reservoirs, yet the genomic mechanisms that enable persistence and transmission across divergent hosts remain incompletely understood. Here, we sequenced 61 C. jejuni isolates recovered from multiple host-associated sources in Shenzhen, China, from 2016 to 2023, and analyzed them together with 312 dereplicated publicly available high-quality reference genomes. Phylogenomic analyses resolved three major clades, including one avian-restricted clade and two clades showing frequent cross-host occurrence. Human-associated isolates displayed lower coding density than mammal-associated isolates and significantly higher proteome-level carbon and nitrogen demands than avian-associated isolates. Comparative genomic analyses further revealed strong host-associated divergence in chromosome-encoded, plasmid-encoded, and horizontally acquired gene repertoires. In human-derived isolates, 11 dataset-specific human-unique KEGG genes and 48 human-unique virulence-associated genes were identified, and human-associated strains showed the strongest multidrug-resistance signal across both chromosome-encoded and mobile-gene compartments. Resistance-associated functions enriched in human-associated genomes included antibiotic inactivation, efflux-mediated resistance, target protection/replacement/alteration, reduced permeability, and nutrient-acquisition-associated resistance. By contrast, core host-interaction loci remained under strong purifying selection, indicating that major human-associated traits were linked more closely to mobile gene acquisition than to extensive mutation-driven diversification. Together, these findings support a proposed genome-partition framework of host adaptation in C. jejuni, in which relatively stable chromosomal backgrounds are complemented by rapid plasmid- and horizontal-transfer-mediated acquisition of high-impact accessory genes. Full article

Understanding the genetic changes that allow avian influenza A viruses (IAVs) to switch their natural hosts and establish productive infection in humans is important for pandemic risk assessment. Adaptations in the IAV polymerase are required to overcome species-specific restrictions imposed by host ANP32 proteins. Notably, avian virus polymerase is generally only poorly supported by human ANP32 proteins due to species-specific differences. Consequently, efficient polymerase adaptation to the binding interface of human ANP32 requires distinct amino acid changes, such as PB2 E627K. A separate adaptation, PB2 M631L, has recently been reported in mammalian-adapted IAV; however, its functional role across divergent viral lineages and its relationship to host ANP32-dependent adaptation remain incompletely defined. Here, we examine PB2 M631L in the polymerases of a 1918 pandemic strain, a recombinant contemporary H1N1pdm09, and a recent clade 2.3.4.4b H5N1 virus. Using polymerase activity and protein-interaction assays, we show that PB2 M631L enhances polymerase activity and ANP32 binding in human—but not avian—contexts, and that this effect is conserved across multiple viral backgrounds. In H1N1pdm09, PB2 M631L also increased virus replication in mammalian cells. These findings indicate that PB2 M631L contributes to enhanced polymerase compatibility with human ANP32 proteins and are consistent with a role in adaptation across multiple influenza virus lineages. Our results highlight how analysis of historical pandemic strains can inform risk assessment for future emerging viruses. Full article