Avian Pathology最新文献

Broiler ascites syndrome is a common and complex disease in broiler farming, which severely impacts broiler growth performance and health and brings huge economic losses to the breeding industry. Hypoxia has been shown to be an important cause of this disease. Prolonged exposure of broiler chickens to a hypoxic environment induces pulmonary vasoconstriction, which leads to an increase in pulmonary artery pressure, triggering pulmonary artery remodelling and compensatory right ventricular hypertrophy, and ultimately ascites. Pulmonary artery remodelling is a process in which the vascular wall tissue structure and function undergo pathological changes after the pulmonary artery is stimulated by various injuries or hypoxia, including endothelial dysfunction, abnormal proliferation of pulmonary artery smooth muscle cells, vascular fibrosis, etc. When these cells are damaged or stimulated, they may undergo programmed cell death, an orderly and regulated mode of cell death that is important for maintaining the stability of the body's internal environment. It has been demonstrated that death modes such as apoptosis and autophagy are involved in the pathophysiologic process of pulmonary hypertension, but their specific molecular mechanisms are still unclear. In this review, we first describe the pathogenesis of broiler ascites, then describe the specific mechanism of dysfunction of pulmonary artery vascular cells in broiler ascites syndrome, and finally elaborate the progression of different programmed cell death in broiler pulmonary hypertension. This study aims to elucidate the specific mechanisms underlying the dysfunction of pulmonary artery vascular cells in broiler pulmonary hypertension, thereby enhancing our understanding of the pathogenesis of this syndrome.

Salmonella, an important foodborne zoonotic pathogen, can be transmitted both vertically and horizontally. It is difficult to control and effectively decontaminate Salmonella, and it poses a serious threat to food safety. Therefore, to prevent the spread of salmonellosis, there is an urgent need for a rapid, accurate and sensitive assay to detect the prevalence of Salmonella in duck flocks. In this study, we utilized biological software to predictively screen the highly conserved Salmonella-specific proteins SpiC, PrgH and PagN. The recombinant proteins PrgH, SpiC, PagN were screened for sensitivity based on individual proteins and pairwise combinations (SpiC + PrgH, SpiC + PagN and PrgH + PagN). A specific and sensitive dual-protein combination, PrgH + PagN, was used as an antigen. Subsequently, PrgH-PagN was produced by tandem expression and employed as the coating antigen in an indirect ELISA (iELISA) for detecting Salmonella antibodies in duck serum. The optimal antigen coating concentration was determined to be 1 μg/ml, with a critical value of OD₄₅₀ = 0.154. The cross-reactivity test results showed no evidence of cross-reactivity with known positive serums from ducks infected with S. Enteritidis, S. Typhimurium, S. Kottbus, E. coli, Streptococcus or Staphylococcus. Screening of 611 duck serums was performed to determine an overall positive rate of 22.09%. The final compliance rate of 93.1% was determined by comparison with that of the commercial kit. In conclusion, the PrgH-PagN-iELISA established in the present study was an accurate and reliable method, with high sensitivity and specificity for detecting antibody responses to systemic Salmonella infections in ducks.

Salmonella Gallinarum is a bacterium that causes significant economic losses in poultry farming and usually infects adult birds. This study aimed to characterize the unusual histological findings and genetic profile of a Salmonella Gallinarum (SG) strain isolated from a natural outbreak that affected 1500 broiler chicks in their first week of life. To confirm the diagnosis, necropsy, histopathology, and immunohistochemistry were performed on 19 chicks, with bacterial isolation in two of them, followed by confirmation through PCR, genetic sequencing, and genomic analysis. The outbreak revealed unusual gross and histological lesions: in the intestines, there was macroscopic haemorrhage of varying severity and, microscopically, the lesions were characterized by histiocytic and heterophilic transmural typhlitis; in the lungs, there was histiocytic interstitial pneumonia of varying intensities. Additional lesions included splenitis, myocarditis, and hepatitis. Salmonella was in situ-labelled in all mentioned organs using immunohistochemistry. Following the virulome and resistome analysis, which compared the genetic profile of the isolate with a reference SG genome, it was found that the isolate from this outbreak contained 36 exclusive virulence genes and six exclusive antimicrobial resistance genes. These genetic alterations may explain the severe systemic lesions observed in these chicks.RESEARCH HIGHLIGHTSSalmonella Gallinarum infection in chicks resulted in a mortality rate of 42%.Chicks had unusual lesions such as haemorrhagic enteritis and interstitial pneumonia.Whole genome analysis of the SG isolate revealed exclusive antimicrobial resistance genes.Higher number of exclusive virulence genes were related to severe fowl typhoid in chicks.

Avian pathogenic Escherichia coli (APEC) infections in poultry adversely affect health and production, with public health implications. This study assessed the potential of bioluminescence imaging for real-time, noninvasive tracking of microbial progression in 12-day-old chicken embryos inoculated with an APEC strain or its derivatives integrated either with luxABCDE or ilux2 operon. Eggs were imaged daily for bioluminescence detection, with dead embryos sampled immediately and survivors killed at 5-days post-inoculation (dpi). The eggs were opened, and egg contents were imaged for bioluminescence. Yolks were sampled for E. coli isolation and quantification. The results showed lethality rates of 100%, 93.3%, and 80% in embryos inoculated with native strain, luxABCDE, or ilux2, respectively. Bioluminescence analysis showed increased bioluminescence signal strength over time preceding embryo death. Surviving embryos exhibited a sequential reduction in signal strength. A strong positive correlation was found between bioluminescence signal intensity in ovo and ex ovo, with ilux2-APEC-infected eggs showing a higher luminoscore than luxABCDE-APEC. The E. coli load in yolks of APEC-inoculated eggs showed a positive trend over time. Overall, bioluminescence imaging of ilux2 operon-labelled bacteria enabled more efficient real-time detection and monitoring of E. coli in ovo. Multiple imaging sessions on the same embryo throughout the experiment allowed precise monitoring of infection progression without sequential culling. This offers a controlled platform for evaluating antimicrobial treatment efficacy in an in ovo model that closely resembles an in vivo chicken model. It can also be used to study infection patterns of other pathogens, especially those that pose risks to public health.RESEARCH HIGHLIGHTSBioluminescence imaging enabled real-time, noninvasive tracking of a bioluminescent APEC infection in embryonated chicken eggs over time.Bioluminescence signals showed contrasting patterns for dead and surviving embryos.The ilux2-APEC showed a higher luminoscore than luxABCDE-APEC in inoculated embryonated chicken eggs.The in ovo bioluminescent signal from intact eggs effectively reflects the ex ovo signal following the take out of yolk and embryo.

Over the last decade, the emergence of aviadenovirus infections, namely inclusion body hepatitis (IBH) and gizzard erosion and ulceration syndrome (GEUS) has occurred in Morocco with significant losses to the poultry industry. In this work, 255 suspected flock cases of IBH and GEUS were assessed among various poultry production types in the country from 2012-2024. Macroscopic pathological changes in affected chickens included an enlarged, discoloured liver or a distended gizzard with haemorrhagic content and erosion/ulceration on the koilin layer. Microscopic findings revealed severe necrotic hepatitis, consistent with IBH, and/or necrotizing ventriculitis, which is characteristic of GEUS, with intranuclear viral inclusion bodies (INIB) in the hepatocytes or epithelial cells of the gizzard, which are attributable to fowl adenovirus (FAdV). The real-time PCR results revealed that 71% (182/255) of the suspected FAdV cases tested positive. The prevalence varied by poultry production type, with broiler farms being the most affected at 79% (144/194), followed by layer farms at 15% (28/42), breeder farms at 5% (9/13), and turkey farms at 1% (1/6). Sequencing of the isolates identified FAdV serotype 11 (species D) and serotype 8b (species E) in 22 and six cases of IBH, respectively. Additionally, FAdV serotype 1 (species A) and serotypes 8a and 8b (species E) were detected in nine and two cases of GEUS, respectively. These findings underscore the significant impact of fowl adenoviruses on the Moroccan poultry industry and highlight the need for continuous surveillance and targeted control interventions.RESEARCH HIGHLIGHTSIncrease in FAdV infections (IBH and GEUS) in Morocco over past decade.FAdV-positive cases were mainly found in broiler farms (79%).Identification of FAdV-11 and 8b serotypes for IBH, and FAdV-1, 8a and 8b for GEUS.

Histomonosis, caused by the protozoan parasite Histomonas meleagridis, is a major concern in turkey production due to the lack of licenced drugs and vaccines. Despite various studies on experimental vaccination, the duration of immunity of such a vaccine remains unclear. This study evaluated the long-term efficacy of an attenuated clonal monoxenic H. meleagridis culture in turkeys, focusing on its protective effects. Day-old turkeys were vaccinated orally using a frozen vaccine culture directly, without additional multiplication, and challenged 12 weeks later. The vaccine caused no adverse clinical signs, consistent with prior studies. Instead, vaccinated birds had an improved weight gain and higher body-weight at 42 days. Vaccine uptake was confirmed by the detection of histomonad DNA in faeces starting 14 days post-vaccination, coinciding with the first sampling time point, with 60-70% of birds testing positive by 49 days. Considering all sampling time-points before the challenge, every sampled vaccinated turkey secreted histomonads at least once. Following the challenge, analysed clinical scores showed a more than 20-fold reduction in disease severity in vaccinated birds compared to controls, and survival rates were remarkably higher in the vaccinated group (90%) than in non-vaccinated controls (16%). Overall, this study supports the long-term efficacy of the attenuated H. meleagridis vaccine, providing robust protection against histomonosis, reducing severity of clinical signs and a significant reduction of mortality, organ lesions as well as parasite burden. The vaccine's effectiveness, when administered at day-old, highlights its potential to prevent histomonosis, though challenges remain for widespread use in commercial turkey farming.RESEARCH HIGHLIGHTSLong-term efficacy of attenuated clonal monoxenic H. meleagridis vaccine was evaluated in turkeys.Long-term protection: Vaccine-protected turkeys from histomonosis for up to 84 days.Survival: 90% of vaccinated turkeys survived vs. 16% of non-vaccinated birds.Body-weights: Vaccinated birds weighed more, at 42 and 91-105 days of life.Lesions: Fewer liver/caecal lesions in vaccinated birds.

Captive breeding of endangered species, such as the African Houbara bustard (Chlamydotis undulata) is an essential part of conservation programmes. However, several factors may negatively impact the health and reproductive performance of captive animals, including genital infections. Between 2010 and 2023, a total of 439 cases of salpingo-peritonitis were diagnosed in a flock of African Houbara breeders belonging to a Moroccan conservation project, relying exclusively on artificial insemination and artificial incubation of eggs (annual prevalence from 0.07% to 1.64%). To improve the overall knowledge of reproductive pathology in this avian species, a representative sample of 14 cases registered in 2022 were characterized, combining gross pathology, histopathology, microbiology and molecular biology. Overall, 4/14 bustards died spontaneously and exhibited septicaemic changes, while 10/14 euthanized birds presented signs consistent with chronic salpingo-peritonitis and oviductal impaction. The latter was further confirmed at histopathology and, in eight bustards, was associated with mucosal changes resembling cystic endometrial hyperplasia, a condition commonly reported in mammals and potentially predisposing to secondary bacterial infections. Escherichia coli was isolated from the reproductive tract of 12/14 birds. Molecular characterization of nine selected isolates revealed the presence of several virulence factors associated with avian pathogenic E. coli. The variety of virulence, as well as antimicrobial sensitivity profiles identified, combined with the pathological presentation, suggested the involvement of multiple bacterial strains. Overall, in addition to the presence of specific virulence genes, management and host-related factors should also be considered as important determinants of the pathogenic potential of E. coli in captive African Houbaras.RESEARCH HIGHLIGHTSFirst comprehensive description of salpingo-peritonitis in African Houbaras.First report of cystic oviductal hyperplasia in African Houbaras.Escherichia coli isolated from the reproductive tract of the majority of birds.Several virulence and antimicrobial sensitivity profiles identified.

Research highlights: Fowl typhoid (FT) is a concerning poultry disease caused by S. Gallinarum.Five S. Gallinarum lineages (I to V) were demonstrated in South American farms.S. Gallinarum lineages have specific antimicrobial resistance / virulence genomic profiles.Main FT outbreaks in Brazil have been caused by the specific lineage II.