Avian Pathology最新文献

Research highlights: Identified the role of the hatchery in astrovirus transmission.Sequenced the avian nephritis virus complete genome.Investigated tissue distribution of astrovirus from egg to chicks.Demonstrated co-infection of ANV/CAstV.

The H2N2 avian influenza viruses (AIV) have been reported in the Northeast United States of America (USA) live bird market (LBM) system since 2014. In this study, we investigated the genetic evolution and characterized molecular markers of the recent H2N2 AIVs in LBMs in the Northeast USA. Phylogenetic analyses revealed that the LBM H2N2 lineage has evolved into three distinct subgroups (groups A.1, A.2, and A.3). The group A.1 viruses and some transient reassortants evolved through several independent reassortment events between the LBM H2N2 lineage and North American wild bird-origin AIVs. Separately, a group of phylogenetically distinct novel H2N2 viruses (group B) identified in LBMs completely originated from wild birds, independent from the previous LBM H2N2 lineage that has persisted since 2014. While no molecular evidence of mammalian adaptation was found, the novel H2N2 viruses in the LBM system underscore the importance of updated risk assessments for potential human transmission.

Copper (Cu) is a necessary micro-element and plays important roles in many biochemical processes. However, excessive Cu intake can lead to multi-organ toxicity, especially in the spleen. To gain further insights into the specific mechanisms of splenic toxicity associated with Cu-induced metabolic disorders, 192 one-day-old chickens were selected and randomly divided into four groups for this study. The broilers were fed with diets containing Cu at final concentrations of 11, 110, 220 and 330 mg/kg for 49 days. The results showed that high dietary Cu caused nuclear shrinkage and mitochondrial vacuolization in the spleen and induced splenic injury through regulating the glutathione metabolism, pentose and gluconate interconversion, tryptophan metabolism and glycerophosphatidylcholine metabolism pathways. Moreover, excess Cu could disorder the mitochondrial dynamics via up-regulating the levels of Drp1, Parkin PINK1, and Dynein, and down-regulating the levels of Mfn1, Mfn2 and OPA1. Cu treatment increased the levels of LC3A, LC3B, mTOR, Beclin1, and ATG5 and decreased the p62 level to promote autophagy of splenocytes. Meanwhile, a high dose of Cu promoted splenocyte apoptosis by increasing the levels of p53, BAK-1, Bax, Cyt C and Caspase-3 and decreasing the level of Bcl-2. These results demonstrated that high dietary Cu could cause autophagy and apoptosis via inducing metabolic disturbances and disordering mitochondrial dynamics in the spleen of broiler chicken.

The infectious bursal disease virus (IBDV) is a significant pathogen affecting the poultry industry worldwide. Its epidemiological history has been marked by the emergence of strains with different antigenic, pathogenic, and genetic features, some of which have shown notable spread potential. The A2dB1b genotype, also known as novel variant, has become widespread and gained increased relevance in IBDV epidemiology. This genotype was described in China in the 2010s and rapidly spread in Asia and Africa. The present study describes the circulation of the A2dB1b genotype in Argentina. Applying a next-generation sequencing approach, we obtained the complete coding sequence of 18 Argentine viruses. The high level of genomic homogeneity observed amongst these viruses, their monophyletic clustering in both partial and complete segments A and B derived phylogenies, and their close relatedness to some Chinese strains suggest that a unique transcontinental spread event from China to Argentina occurred recently. The apparent success of the A2dB1b genotype spreading throughout Asia, Africa, and South America may partially be due to specific amino acid characteristics. Novel residues in the hypervariable region of VP2 may help A2dB1b IBDVs evade the protection elicited by the applied commercial vaccines. Our findings underscore the importance of continuous characterization of field samples and evaluation of the control measures currently applied to fight against this specific IBDV genotype.

The purpose of the present study was to examine if potentiation of mortality occurred after simultaneous administration of several Escherichia coli genotypes, each capable of inducing the E. coli peritonitis syndrome, in comparison with single genotype application. Five groups of productive specified pathogen free White Leghorn hens were housed in isolators. Groups 1-4 consisted of 32 hens each, group 5 of 10 hens. At 32 weeks of age all groups were inoculated intratracheally. Groups 1 and 2 were inoculated with a mix of four E. coli genotypes and groups 3 and 4 with a mix of four other genotypes. Groups 1 and 3 were given 1 median lethal dose (LD₅₀) of each genotype per hen and groups 2 and 4 had a dose of 0.1 LD₅₀ per genotype per hen; group 5 was mock inoculated. The experiment ended one week after inoculations. In Group 5, no mortality occurred and gross lesions were absent at post-mortem examination. Mortality in groups 1 and 3 was 84% and 81%, respectively; in groups 2 and 4 59% and 66%, respectively. Although mortality in groups 1 and 3 exceeded the expected 50%, this could not be due to potentiation as cluster analysis of reisolates showed that in individual hens only one genotype was found, indicating interference between E. coli genotypes. In groups all four or only two genotypes were recovered, showing that not all genotypes will induce colibacillosis in all experimental groups. Therefore, broad protection can be best assessed by challenging with various single genotypes.RESEARCH HIGHLIGHTS All four or only two E. coli genotypes were found in groups of hens given mixes of four genotypes.In contrast, only one genotype was found in individual hens.E. coli genotypes interfere with each other in hens after given as a mix.Interference is likely based on a random process.Broad protection can best be assessed by challenging with single genotypes.

Coccidiosis, caused by parasites of the genus Eimeria, is a significant economic burden to the poultry industry. In this study, we conducted a comprehensive analysis to evaluate the financial losses associated with Eimeria infection in chickens in Algeria, relying on data provided by key stakeholders in the Algerian poultry industry to assess sub-clinical as well as clinical impact. We employed the updated 2020 version of a model established to estimate the cost of coccidiosis in chickens, taking into consideration specific cultural and technical aspects of poultry farming in Algeria. The findings predict economic losses due to coccidiosis in chickens of approximately £86.7 million in Algeria for the year 2022, representing £0.30 per chicken raised. The majority of the cost was attributed to morbidity (74.9%), emphasizing the substantial economic impact of reduced productivity including decreased bodyweight gain and increased feed conversion ratio. Costs associated with control measures made up 20.5% of the total calculated cost, with 4.6% of the cost related to mortality. These figures provide a clear indication of the scope and economic impact of Eimeria infection of chickens in Algeria, illustrating the impact of practices common across North Africa. They underscore the ongoing requirement for effective preventive and control measures to reduce these financial losses while improving productivity and welfare, ensuring the economic sustainability of the Algerian poultry industry.

Avian influenza (AI), caused by H9N2 subtype avian influenza virus (AIV), poses a serious threat to poultry farming and public health due to its transmissibility and pathogenicity. The PB2 protein is a major component of the viral RNA polymerase complex. It is of great importance to identify the antigenic determinants of the PB2 protein to explore the function of the PB2 protein. In this study, the PB2 sequence of H9N2 subtype AIV, from 1090 to 1689 bp, was cloned and expressed. The recombinant PB2 protein with cutting gel was used to immunize BALB/c mice. After cell fusion, the hybridoma cell lines secreting monoclonal antibodies (mAbs) targeting the PB2 protein were screened by indirect ELISA and western blotting, and the antigenic epitopes of mAbs were identified by constructing truncated overlapping fragments in the PB2 protein of H9N2 subtype AIV. The results showed that three hybridoma cell lines (4B7, 4D10, and 5H1) that stably secreted mAbs specific to the PB2 protein were screened; the heavy chain of 4B7 was IgG2α, those of 4D10 and 5H1 were IgG1, and all three mAbs had kappa light chain. Also, the minimum B-cell epitope recognized was ⁴⁷⁵LRGVRVSK⁴⁸² and ⁵²⁸TITYSSPMMW⁵³⁷. Homology analysis showed that these two epitopes were conserved among the different subtypes of AIV strains and located on the surface of the PB2 protein. The above findings provide an experimental foundation for further investigation of the function of the PB2 protein and developing monoclonal antibody-based diagnostic kits.

Since the detection of antigenically atypical very virulent Infectious bursal disease viruses (vvIBDV) in Egypt in 1999, the country has been experiencing recurrent outbreaks with high mortality rates and typical gross lesions associated with typical vvIBDV. However, a significant change occurred in 2023, marked by a notable increase in reported subclinical IBDV cases. To evaluate the field situation, samples from 21 farms in 2023 and 18 farms from 2021 and 2022, all of which had experienced IBD outbreaks based on clinical diagnosis, were collected, and subjected to VP2-HVR sequencing. Phylogenetic analysis revealed that all samples collected in 2021 and 2022 clustered with classical virulent strains and vvIBDV. In 2023, one sample clustered with the Egyptian vvIBDV, another with classical virulent IBDV, and the rest with the novel variant IBDV (nVarIBDV) circulating in China. The alignment of deduced amino acid sequences for VP2 showed that all Egyptian classic virulent strains were identical to the Winterfield or Lukert strains, while vvIBDV strains exhibited two out of the three typical residues found in Egyptian vvIBDV, namely Y220F and G254S, but not A321T. Meanwhile, all Egyptian variant strains exhibited typical residues found in nVarIBDV. However, all Egyptian variants showed a mutation at position 321 (321V), which represents the most exposed part of the capsid and is known to have a massive impact on IBDV antigenicity, except for one sample that had 318G instead. This report highlights the emergence of a new variant IBDV in Egypt, clustered with the Chinese new variants, spreading subclinically in broiler farms across a wide geographic area.RESEARCH HIGHLIGHTS New variant IBDV which emerged in Egypt clustered with Chinese nVarIBDV.nVarIBDV spread subclinically across a wide geographic area.Mutation at 321 represents capsid's most exposed part, a defining feature.Antigenically modified vvIBDV still circulating in Egypt with typical lesions.