Avian Pathology最新文献

The keel bone in laying hens is prone to fractures, especially on the caudal third of the keel, which is also the last part to ossify. Keel bone fractures (KBF) typically occur between 25 and 50 weeks of age (WOA). However, the keel is fully ossified at around 40 WOA, suggesting fractures can occur before ossification is complete. To better understand the relationship between KBF and ossification, this descriptive study examined keel bone morphology during maturation. Keel bones from 50 commercial aviary housed Dekalb White laying hens were collected at 10 timepoints from 17-53 WOA and prepared for histological analysis. The samples were stained with haematoxylin and eosin and Safranin O to show cartilage, ossification, bone tissue, and KBF. The results indicated an ossification process similar to endochondral ossification. The degree of ossification varied between individuals of the same age. The age at complete ossification varied from 28-49 WOA. None of the keels from hens aged 53 WOA were fully ossified. Cartilage canals were present in the keel cartilage. Medullary bone was observed in all age groups. Most fractures lacked tissue morphologies typical of high-impact collisions, suggesting the need for further research into the underlying causes. This is the first study to detail keel bone histomorphology in commercial laying hens, providing baseline data for future research.

Research highlights: Goose astrovirus type 2 (GoAstV-2) became the dominant strain in China post-2017.GoAstV-2 exhibits weaker codon usage bias, enhancing adaptability across hosts.The stability of GoAstV-2 spike protein reduces mutation needs and selective pressure.GoAstV-2 low spike protein variability supports long-term persistence in host populations.

Research highlights: ttrA and pduA double mutants in Salmonella provoke a similar immune response.SE elicited more intense immune responses than STM.The immune response in the broiler was more intense than in other lineages.

ABSTRACTAvian trypanosomiasis is caused by flagellate protists of the genus Trypanosoma (Trypanosomatidae, Kinetoplastida). These parasites are transmitted by various blood-sucking arthropods. While these parasites are generally considered to have low pathogenicity, certain species can induce clinical symptoms in susceptible birds. In this study, detail morphological and molecular characteristics of Trypanosoma species isolated from domestic chicken (Gallus gallus domesticus) in Northeastern Thailand were investigated. In total, 58 buffy coat blood films, 60 thin blood films of fresh blood and 60 partial DNA sequences were analysed. Subsequently, Trypanosoma avium and Trypanosoma calmettei, which are rarely reported species in poultry as well as Trypanosoma sp. were characterised. Additionally, we provided the details of reviewed information of the parasite morphometry in different avian hosts. Phylogenetic analysis identified the most closely related avian Trypanosoma lineages. This study reports T. avium in domestic chickens and along with molecular characterization of T. calmettei, which are rarely reported species. Buffy coat and nested-PCR diagnostic methods were nearly similar in terms of sensitivity for trypanosome diagnostics, and both methods were more sensitive in comparison to microscopic examination of thin blood films. Relatively cheap buffy coat method is helpful for screening of trypanosomes infection in poultry, particularly during rapid fieldwork. In parasitology research, buffy coat and nested-PCR diagnostics are worth combining with thin blood smear microscopic examination, which provides valuable information about non-deformed trypomastigotes that are essential for morphospecies identification.

Duck circovirus (DuCV) is one of the most prevalent infectious viruses in the duck industry in China. Although the clinical signs vary, it often causes immunosuppression in the host and leads to secondary infection with other pathogens. Novel goose parvovirus (NGPV) mainly infects ducks and causes short beak and dwarfism syndrome in ducks. However, the incidence of infection in ducks has increased in recent years, and the phenomenon of mixed infection with DuCV is common, resulting in more severe clinical morbidity. However, there are no systematic studies evaluating the presence of mixed infections. In order to investigate the synergistic pathogenicity of DuCV and NGPV co-infection in SPF ducks, a comparative experiment using DuCV and NGPV co-infection and mono-infection bird models was established. The results showed that the clinical signs of short beak, dwarfism and immunosuppression were more obvious in DuCV and NGPV co-infected ducks; the tissue damage of target organs was more serious, and the viral titre in organs and cloacal swabs were more significant compared with those of SPF ducks infected with only one virus. The results indicated that co-infection with DuCV and NGPV could promote viral replication and cause more severe tissue damage and immunosuppression than single virus infection. The present study reveals that the co-infection of NGPV and DuCV has a synergistic pathogenic effect from the aspect of pathogenicity, and the conclusions drawn not only clarify the direction of the subsequent research on the mechanism of co-infection of NGPV and DuCV, but also provide a scientific basis for the research on the co-infection of immunosuppressive pathogens and other pathogens.

Research highlights: Development of nr-NDV.Reverse transfection was applied for the recovery of nr-NDV.Propagation of nr-NDV was done by sub-passaging transfected BSR T7/5 cells.Safety profile was done to prove that the nr-NDV is non-replicating.

Infectious bronchitis virus (IBV) is the first coronavirus discovered in the world in the early 1930s and despite decades of extensive immunoprophylaxis efforts, it remains a major health concern to poultry producers worldwide. Rapid evolution due to large poultry population sizes coupled with high mutation and recombination events and the reliance of the antiviral immune response on specific antibodies against the epitopes of the S1 glycoprotein, render the control of IBV extremely challenging. The numerous and rapidly evolving genetic and antigenic IBV types are currently classified based on the whole S1 gene sequence, into 36 lineages clustered in eight genotypes. Most lineages (29) are grouped in genotype I (GI). "Variant 2" (Israel/Variant 2/1998) is the prototype strain of lineage GI-23 and, since this lineage emerged during the mid-1990s in the Middle East, it has evolved into numerous genetically related strains and disseminated to five continents. The hallmarks of IBV Variant 2-like strain infections are high virulence and remarkable nephrotropism and nephropathogenicity; however, the molecular mechanisms of these traits remain to be elucidated. Limited protection from previously utilized vaccine strains and accumulated losses to poultry producers have urged the development and implementation of homologous Variant 2-like vaccine strains. The latest avian coronavirus biology with specific emphasis on the cumulative knowledge about IBV "Variant 2" and emergence of related strains, characteristics and control are reviewed.

Research highlights: Detection timepoints and patterns indicate horizontal introduction of various enteric viruses.Flock infection profiles were very heterogeneous; no dominating virus profile.Broiler production was negatively affected by the number of enteric viruses detected.Common biosecurity measures had a significant negative effect on virus prevalence.

Research highlights: First confirmation of AOAV-16 in domestic and wild birds in China.AOAV-16 are low virulent viruses for chickens.Co-circulation/co-infection of AOAV-16 and H9N2 subtype AIV enhanced pathogenicity.Different intergenic sequences and recombination events exist within AOAV-16.

Liposomal encapsulated phytogenics, such as liposomal hesperetin, are considered novel substitutes for antibiotics in the broiler industry owing to their improved nutritional and therapeutic properties. Therefore, our key goal was to investigate liposomal hesperetin impact on broiler growth performance, health, antioxidant status, tight junction proteins (TJP), and resistance against Listeria monocytogenes. Four broiler groups were fed 0, 150, 250, or 400 mg/kg of liposomal hesperetin-supplemented diets and experimentally infected with L. monocytogenes strain. Herein, liposomal hesperetin, especially at higher concentrations, augmented broilers FCR with upregulation of genes encoding TJP (occludin, JAM-2, MUC-2), and antioxidant attributes (GPX-1, SOD-1, CAT, HO-1, NQO1, COX2), which reflect enhancing health and welfare of broilers. Muscle antioxidant biomarkers were enhanced; meanwhile, muscle MDA, ROS, and H₂O₂ levels were reduced in response to 400 mg/kg of liposomal hesperetin. Liposomal hesperetin fortification reduced L. monocytogenes loads and expression levels of its virulence-related genes (flaA, hlyA, and ami). Remarkably, histopathological alterations in intestinal and brain tissues of L. monocytogenes-infected broilers were restored post-inclusion at higher levels of liposomal hesperetin, which reflects increase of the birds' resistance to L. monocytogenes infection. Transcription levels of genes encoding cytokines/chemokines (MyD88, AVBD6, CCL20, IL-1β, IL-18), and autophagy (Bcl-2, LC3, AMPK, AKT, CHOP, Bip, p62, XBP1) were ameliorated following dietary liposomal hesperetin fortification, which suggests enhancement of the birds' immunity and health. Collectively, our research recommends liposomal hesperetin application in broiler diets owing to its promoting impact on growth performance, antioxidant status, immunity, health, and welfare besides its antibacterial, and antivirulence characteristics to fight against L. monocytogenes.