Avian Pathology最新文献

Research highlights: Type O8 is the most prevalent serotype of APEC isolated from Wenchang chicken embryos (Hainan, China).The isolates were more than 90% resistant to erythromycin, amoxicillin, ampicillin, and tetracycline.19.2% of the isolates were multi-resistant to more than 14 antibiotics.APEC of the same serotype isolated from Hainan Wenchang embryos have close relationships in the evolutionary tree of the core genome.

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.

Research highlights: The prevalence of trypanosomes in chickens is high.The first report of Trypanosoma avium in chickens with evidence of species identification.The first report of morphological and molecular characteristics of Trypanosoma calmettei.A cheap and quick buffy coat method is helpful for screening trypanosomes.

Eighty, 1-day-old (DO) broiler chicks and 80 1-DO male layer chicks were experimentally infected with two isolates of fowl adenovirus D (FAdV-D) serotype 2 isolated from broiler chickens suffering inclusion body hepatitis (IBH) (accession numbers ON603311 and ON603320). Clinical observation was performed up to 28-DO, and samples from the liver, pancreas, kidneys, spleen, thymus, and bursa of Fabricius were collected for histopathological examination. Furthermore, FAdV-D viral shedding was tested up to 21DO. Serological response to IBH (FAdV-D) through enzyme-linked immunosorbent assay (ELISA) and blood biochemical analysis, as well as polymerase chain reaction (PCR) testing for some innate immune response parameters (interleukins and cytokines) to IBH were applied. Also, immune response of chicks to avian influenza and Newcastle disease vaccines was evaluated using the haemagglutination inhibition (HI) test. No mortality was observed following experimental infection of either broiler or layer chicks with FAdV-D serotype 2 isolates, despite the clearly evidenced histopathological damage in the liver, pancreas, kidneys, spleen, thymus, and bursa of Fabricius. Viral shedding extended to 21DO. Neither isolate could induce serological response, but both elevated the interleukins and cytokines. In conclusion, broilers were more susceptible to IBH-FAdV infection than layer chicks. FAdV-D serotype 2, which causes IBH, had an immunosuppressive effect on chickens.

The haemolysin co-regulatory protein (Hcp) plays a significant role in the pathogenicity of avian pathogenic Escherichia coli (APEC) as an effector protein of the type VI secretion system (T6SS) to the host. Meanwhile, mitochondria in the host are the target of effector proteins of various secretion systems. Here, we explored the effects of APEC effector Hcp2b on the mitochondria of DF-1 cells and found that Hcp2b results in damage in mitochondria. Next, 68 target proteins in DF-1 cell lysates were identified that interacted with Hcp2b by streptavidin-biotin pull-down assay combined with LC-MS/MS, among which ADP/ATP transporter carrier (SLC25A4) is a mitochondria-associated protein; protein docking analysis showed that Hcp2b binds well to SLC25A4. Therefore, we hypothesize that the Hcp2b contributes to mitochondrial damage in DF-1 cells through interaction with the SLC25A4.

Reticuloendotheliosis virus (REV) is a species of the genus Gammaretrovirus that can cause neoplasia, immunosuppression, and runting-stunting syndrome. To show the clinical relevance of REV is complicated, and requires the demonstration of the virus, REV antibodies, the presence of typical gross and microscopic lesions, and the exclusion of other oncogenic agents in the case of the presence of tumours. Under field conditions, the first tests to be used might be a commercially available REV antibody ELISA or an RT-PCR to detect the REV genome. In this short paper, we present the experiences with two commercially available ELISAs and RT-PCR that we have gained from a REV outbreak on a large multi-age layer farm and many follow-up tests on samples from control farms with and without a known history of REV and fowlpox virus (FPV). In the field, some of the FPV field strains contain large inserts of the REV genome that might interfere with REV testing. The results of the ELISAs on sera from REV- and FPV- unsuspected flocks suggested that the cut-offs of both ELISAs were somewhat low resulting in a lower specificity. However, cut-offs of 2000 and 3050 for the IDEXX and BioChek ELISAs, respectively, gave an agreement of 100%, suggesting that these cut-offs might be advisable to use. The use of the combination of RT-PCR for REV and PCR for FPV proved to be very useful in separating REV infections from FPV infections. The results of our extended field study can help to interpret REV testing results.

In the last decade, the emergence of variant strains of avian orthoreovirus (ARV) has caused an enormous economic impact on the poultry industry across China and other countries. This study aimed to evaluate the molecular evolution of the ARV lineages detected in Chinese commercial broiler farms. Firstly, ARV isolation and identification of commercial broiler arthritis cases from different provinces in China from 2016 to 2021 were conducted. A total of 51 pure ARV isolates were obtained. Sequencing results showed that there were five genotypes of the strains isolated in this study, of which genotype 1 ARV predominated, accounting for 56.9% (29/51). The whole gene sequences of 19 ARV representative isolates were successfully obtained. The genetic evolution analysis of 10 genome segments of 19 ARV isolates showed that the σC-encoding gene had evolved into six different lineages, while the other genome segments only differentiated into two to four different lineages. The results of recombination analysis showed that recombination events were present in the L3, M1 and S1 genome segments. Analysis of the variation of the key factor σC protein showed that the nucleotide and amino acid homologies of the σC were low among the different genotypes. Three-dimensional structural visualization analysis showed that all the structural changes of σC protein were concentrated in the spherical domain at the C-terminal, which is associated with host receptor binding.

Ascites syndrome (AS) is a deadly condition in fast-growing chickens, preceded by pulmonary arterial hypertension (PAH), where the angiotensin II type 1 receptor (ATR1) plays a role. We investigated whether allicin (ALLI), a garlic derivative, could (a) interact with broiler ATR1, (b) affect ascites-related traits [haematocrit content (Hct%), blood oxygen saturation (SaO₂), and the right-to-total ventricular weight ratio (RV:TV)], (c) modify ATR1 expression in the lung, heart, and liver, alongside ascites mortality and growth performance in Ross 308 broilers raised at high altitude and under cold temperatures promoting PAH/AS. Three groups (n = 70 each) were studied: 0-ALLI (untreated), 1-ALLI (allicin 1 mg/kg bodyweight/daily at 14-27 days of age by oral-oesophageal route), and 2.5-ALLI. After 3-6 weeks, Hct%, SaO₂, RV:TV ratios, and ATR1 expression in the lung, heart, and liver, were evaluated. Weekly productive performance and AS mortality were recorded. Molecular dockings and dynamic simulations predicted that ALLI might inhibit broiler ATR1 in a transitory manner. At 42 days of age, birds in the 2.5-ALLI group exhibited lower Hct% and lower RV:TV values, while ALLI marginally enhanced SaO₂. ATR1 expression in the 1-ALLI and 2.5-ALLI groups was higher (i.e. restored) in the lungs and heart, respectively, but not in the liver compared with the untreated group. Productive performance remained unaffected by ALLI, and 2.5-ALLI provided a protection of 4.3% against ascites mortality. In conclusion, 2.5-ALLI mitigated PAH/AS traits in the lungs and heart without compromising broiler productive performance. Further studies adjusting ALLI doses and combinations are warranted.RESEARCH HIGHLIGHTS Broilers bred at >2000 m OSL and <20°C were treated with 1 or 2.5 mg allicin per os.Allicin at 2.5 mg per os decreased haematocrit and right ventricular hypertrophy.Allicin treatments restored ATR1 expression in the heart and lungs.Productive performance of broilers was not affected by allicin treatments.Allicin is a promising candidate to enhance the quality of poultry production.

Molecular methods are currently the most sensitive for detecting Chlamydia psittaci in birds. Most laboratories have developed their own molecular assays or adapted published protocols, often making slight modifications to fit their specific study purposes. The sensitivity and specificity of a molecular test depend on the target gene, primer sequences, types of molecular test, DNA extraction method, and sampling methods. We reviewed 120 articles published between 2000 and 2020 to compile information on the molecular detection of C. psittaci in birds. Of the ten genomic targets currently available to detect C. psittaci in birds, the ompA gene was the most widely used. In published surveillance studies, of the fourteen molecular test types, conventional PCR and quantitative PCR were applied the most. A testing strategy using a hierarchical approach that includes molecular tests of genus- and species-specific targets is recommended to detect other avian chlamydial species besides the well-recognized C. psittaci. Samples should be sourced from both the respiratory and gastrointestinal tracts whenever possible for better accuracy. High-quality DNA can be obtained when the sample is preserved in optimal medium and temperature, and an optimized DNA extraction protocol is applied. Standardization and validation of molecular Chlamydia tests are needed to enhance the comparability and reliability of assays to detect C. psittaci and other chlamydiae species in birds.RESEARCH HIGHLIGHTSHierarchical molecular testing is recommended for the detection of avian C. psittaci.Key molecular tests for surveillance were conventional PCR and quantitative PCR.The most used genomic target to detect C. psittaci in birds was the ompA gene.