Live haemorrhagic enteritis virus (HEV) vaccination reduced clinical signs and lesions under field conditions.Vaccination limited field strain circulation and environmental infection pressure.Vaccinated turkey flocks remained protected from HEV until slaughter age.

Enteritis syndrome in French red-legged partridge flocks.Detection of novel enteric coronaviruses (ParCoVs).ParCoVs are phylogenetically close to French TCoVs.Significant genetic variability of ParCoVs ruled out a clonal cluster of cases.Avian coronavirus RNA detected in intestinal sections by RNAscope ISH.

No association between the sampling period and APEC status was observed.Antibiotic treatments did not affect the prevalence of APEC isolates observed.Antimicrobial resistance patterns in E. coli strongly correlated with antibiotic use.

Infectious bronchitis virus (IBV) remains a major threat to poultry production worldwide, with the GI-23 lineage emerging as one of the most epidemiologically relevant variants in recent years. Although GI-23 has been reported in Brazilian commercial poultry, its occurrence and genomic characteristics in backyard poultry remain poorly understood. This study investigated the molecular epidemiology and evolutionary features of IBV circulating in backyard poultry from São Paulo State, Brazil. Samples from 893 backyard birds were screened for IBV using RT-qPCR targeting the 5' untranslated region (5'UTR). Positive samples were further characterized by lineage-specific RT-PCR assays, S1 gene sequencing, virus isolation, and whole-genome sequencing, followed by phylogenetic, phylogenomic, and recombination analyses. IBV was detected exclusively in chickens, with an overall prevalence of 13.8% (42/304 swab pools; 95% CI: 10.1-18.2). Among RT-qPCR-positive samples, 23.9% were identified as belonging to the GI-23 lineage, while GI-1 and GI-11 lineages were not detected. Phylogenetic analysis of partial S1 gene sequences revealed multiple GI-23 sublineages circulating in Brazil, indicating different viral introductions. Whole-genome sequencing of a Brazilian GI-23 isolate showed high identity to a virus identified in Mexico and revealed recombination events involving European and Middle Eastern IBV lineages. These findings provide the molecular and genomic evidence of IBV GI-23 circulation in Brazilian backyard poultry and highlight the importance of monitoring viral evolution and supporting effective disease control strategies.

AbstractThe Newcastle disease virus (NDV) is the etiological agent of a highly transmissible avian disease, first recognized in 1926. The virus continues to pose a substantial threat to both commercial and domestic poultry farming globally, causing major outbreaks with high mortality rates and resulting in considerable economic losses. Despite the widespread use of vaccines and other control measures outbreaks persist. This is linked to the NDV significant genetic variability, its capacity to evolve under selective pressure and its wide range of natural hosts, with diverse virus variants continuing to circulate globally in both domestic and wild birds. Wild synanthropic and migratory birds play an important role in maintaining the virus and transmitting it across regions and continents. Summarized monitoring data from different countries evidences global picture of up-to-date virus distribution and changes in the different virus variant composition from 2017-2026. Some commonly used tests may miss newly emerging variants, and diagnostic procedures thus have to be regularly modified.

The avian influenza virus (AIV) poses a serious threat to the poultry industry, leading to substantial economic losses and having the potential to cause severe zoonotic diseases worldwide. The development of mucosal vaccines has prompted greater attention due to their ability to mimic the natural infection process and streamline the delivery method. In this study, we evaluated the efficacy and immunomodulatory responses of an intranasal vaccine containing inactive H5N1 virus and bacterial sialidase with mucoadhesive chitosan adjuvant. The results demonstrated that the challenged intranasally vaccinated group exhibited a significantly suppressed mortality rate and viral shedding compared to the group infected with H5N1 AIV. Additionally, elevated mucosal IgA at several days post intranasal vaccination indicated activation of the nasal-associated lymphoid tissue (NALT) and improvement of cell-mediated immune responses. Gene expression analysis of the innate immune system revealed significant downregulation of TLR7 and diminished interferon responses in brain and lung tissues, suggesting restricted viral recognition and replication. In the trachea, challenged birds exhibited selective upregulation of IFN-γ, while the vaccinated group had no substantial activation, indicating that intranasal vaccination modulated local immune responses at the viral entry site. In conclusion, intranasal vaccination reduced tissue damage, suppressed viral shedding, and improved mucosal protection, demonstrating its potential as a candidate strategy to manage H5N1 AIV outbreaks.

Attaching and effacing Escherichia coli (AEEC) are increasingly recognized as causes of enteric and systemic disease in birds. However, large-scale outbreaks in psittacines are seldom reported. We describe a severe AEEC outbreak in a colony of 144 lorikeets (Trichoglossus spp.) in an indoor walk-through zoo enclosure in the Netherlands, which resulted in 75.7% mortality (109/144) and additional mortality in cohabiting species. Affected birds showed nonspecific signs, including lethargy, inappetence, recumbency, and death within 24 h. Necropsy revealed enteritis with intramural and hepatic abscesses, and histopathology confirmed multiorgan inflammation and septicaemia. E. coli was consistently isolated from intestinal and hepatic lesions; PCR and whole genome sequencing identified multiple co-occurring AEEC pathotypes. Nectar feed samples demonstrated contamination and rapid bacterial proliferation, implicating inappropriate feed as the most probable outbreak source. This event represents one of the few documented E. coli-associated mass mortality events in captive psittacines and the first to propose simultaneous circulation of distinct AEEC variants during a single outbreak. The findings highlight the pathogenic potential of AEEC in lorikeets and the need for strict feed hygiene, vector control, and molecular surveillance in zoo biosecurity and One Health contexts.

Despite use of aMPV vaccines, clinical signs of disease caused by aMPV infection with field strains were widely reported in poultry production in Poland.The strains detected formed a distinct cluster of "Polish field strains".Two complete aMPV-B genomes revealed several non-synonymous mutations, especially in G and SH genes, that may account for the poor protection provided by the vaccines.Phylogenetic analysis of two Polish complete genomes revealed a significant genetic distance from available aMPV-B strains.

West Nile virus (WNV) is one of the most widely distributed zoonotic arthropod-borne viruses in the world and has been identified as the cause of potentially fatal disease in birds. While the pathomorphology and virus distribution in birds are well documented for WNV lineage 1 (WNV-1) epizootics in North America, few (histo-)pathological and immunohistochemical studies are available for Europe, where WNV lineage 2 (WNV-2) is co-circulating with WNV-1. WNV-2 infected dead birds were evaluated (histo-)pathologically at the German regional veterinary laboratories and academic pathological institutes. Immunohistochemical labelling (IHC) with an in-house rabbit anti-WNV polyclonal antibody (OM8) and subsequent evaluation of IHC signal distribution were performed at the National Reference Laboratory. In total, tissues of 54 birds from 32 different species, including first-time descriptions in endangered avian taxa, were analysed. Gross and histopathological findings aligned well with previous reports of avian WNV disease and the heart was once more confirmed as a reliable target organ for diagnostics. However, the frequent identification of WNV antigen (Ag) in enteric ganglial neurons and glial cells in several bird species, as well as signs of prolonged disease duration in corvids, contrasted with earlier findings on the North American continent. In conclusion, this study broadens the range of avian taxa for which information on pathomorphology and distribution of viral Ag associated with fatal WNV disease is available, and will facilitate diagnostics in the field. Furthermore, some of the described findings differed from the available literature suggesting deviations in the pathogenesis of locally circulating WNV-2 strains.

The increasing prevalence of antigenic variations and genetic reassortments of Infectious Bursal Disease virus (IBDV) across various global regions, causing subclinical infections, poses a significant threat to the poultry industry, leading to substantial losses. In the current study, the protective efficacy of recombinant trivalent vaccine rHVT + IBD + H5, administered once at 1-day old (DO) in the hatchery was assessed against challenge with the most recent circulating novel variant IBD (nVarIBDV), A2dB1b, Egyptian isolate (IBD/EGY/F1335/2023) in commercial broiler, and specific pathogen free (SPF) chickens at 28 DO. A total of 210, commercial broilers and 120 SPF chicks, housed at BSL-3 conditions, were divided into 11 equal groups (Broilers, G1-G7, and SPF G8-G11, n = 30/group). The bursa/body weight ratio (BBR) and bursa/body weight index (BBI) scores calculated at 4-, 7-, 10-, and 14-days post-infection (DPC) revealed significantly higher scores in the vaccinated challenged broiler groups (especially G4) and in the vaccinated challenged SPF group (G8) as compared to their control non-vaccinated challenged groups, G2, G5 and G9, respectively. Additionally, the histopathological and immunohistochemical examinations indicated significantly higher protection in the vaccinated-challenged broilers (G1 and G4) and SPF (G8) groups in comparison to their controls. Overall, this study demonstrated higher protective efficacy of rHVT + IBD + H5 hatchery vaccination against Egyptian nVArIBDV, A2dB1b, especially in the broiler chickens G4 that had specific MDA.

Viral diseases are a major cause of economic losses in the poultry industry. Among these is infectious bursal disease (IBD), which poses a threat to global poultry production. The epidemiology of IBD is changing; while very virulent IBDV (vvIBDV) remains endemic and represents the dominant clinical threat in regions such as Africa and parts of South America, the regional transition towards novel variants (nVarIBDVs) and reassortants (A3B1) is particularly pronounced in Asian and European poultry production, respectively. This review synthesizes global IBD epidemiological data reported up to December 2025 and analyses the evolution of molecular genogrouping and fitness. Ongoing IBDV evolution is accelerating, with Asia becoming the epicentre of nVarIBDV (genogroup A2d), which circumvents maternally-derived antibodies (MDA) and classical vaccine protection. In Europe, the A3B1 reassortant has become the dominant field IBDV strain. The review highlights a nomenclature conflict regarding the A9 designation, which currently refers to both an attenuated strain and a pathogenic variant from Portugal. Considering the 9% divergence threshold, the attenuated IBDV strain should be returned to the A1 genogroup lineage "b" (A1b), while A9 denotes Portuguese variants. Furthermore, phylogenetic analysis reveals that the evolution of segment B (VP1) is independent of segment A (VP2), necessitating a bi-segmental approach. The rapid antigenic drift in VP2, combined with the crucial role of the conserved segment B and the RNA-dependent RNA polymerase (RdRp) in viral pathogenicity, necessitates a shift to a standardized dual-segment phylogenetic classification system (A#xB#y binomial nomenclature) for effective global surveillance.

The GVI-1 genotype of infectious bronchitis virus (IBV) has become increasingly prevalent in Asia. In this study, a highly pathogenic GVI-1 strain (GVI-1-WT) was attenuated by 110 serial passages in embryonated chicken eggs, yielding an attenuated strain (GVI-1-E110). Comparative genomic analysis identified two amino acid substitutions, S523I, Q653R and a nine-amino-acid truncation in the spike (S) protein. To evaluate the contribution of the two point mutations to virulence attenuation, recombinant viruses carrying Q653R and S523I substitutions were generated using a reverse genetics system based on the GVI-1-WT strain as the backbone. Their replication and pathogenicity were assessed in embryonated eggs and specific pathogen-free chickens. The Q653R substitution was associated with reduced viral replication in embryonated chicken eggs and pathogenicity in specific pathogen-free chickens, whereas the S523I mutation alone showed a limited effect but enhanced attenuation when combined with Q653R. However, the attenuation phenotype of the recombinant viruses did not fully recapitulate that of the passaged strain GVI-1-E110, suggesting that additional mutations, including the identified truncation and mutations in replicase-associated genes outside the S protein, may also contribute to virulence attenuation. This study indicates that spike protein mutations are involved in the attenuation of GVI-1 IBV strains, and provides insights into the molecular basis of IBV attenuation during serial passage. Further studies are required to elucidate the underlying mechanisms and to evaluate their potential relevance for vaccine development.

APEC Hcp2b protein translocates into HD11 cells and induces significant cytotoxicity.Hcp2b elicits incomplete autophagy, characterized by blocked autophagic flux.Proteomic analysis demonstrated Hcp2b impairs lysosomes, blocking autophagy.

Four atypical S. Infantis variants differ in the infection dynamics in broilers.Non-motile S. Infantis variants regain motility following host passage.

The H9N2 subtype of avian influenza A virus has been endemic in poultry populations across Asia and the Middle East, posing ongoing economic and public health concerns. Since their initial detection in Pakistan in the 1990s, H9N2 viruses have caused repeated outbreaks in commercial poultry, leading to substantial economic losses and raising concerns about zoonotic transmission. To characterize the recent genetic evolution and zoonotic potential of circulating strains, five H9N2 isolates were obtained from poultry in Pakistan between January and March 2023. Phylogenetic analysis of the haemagglutinin gene revealed that all five isolates belong to the G5.3.2, formerly known as B2, sub-lineage of the G1 Eurasian lineage, in accordance with the revised global classification system for H9 viruses. Comparative genomic analysis confirmed that all eight gene segments were closely related to previously reported Pakistani strains, with no evidence of recent reassortment, suggesting localized persistence and ongoing genetic drift. Notably, several mammalian-adaptive mutations were identified in internal gene segments of the isolates, suggesting a potential risk of cross-species transmission. In addition, all five isolates exhibited dual receptor-binding characteristics, recognizing both α2,3-linked (avian-type) and α2,6-linked (human-type) sialic acid glycans, with a stronger affinity for α2,6-linked glycans. These findings underscore the need for continuous surveillance and risk assessment of H9N2 viruses circulating in Pakistan.