Avian Pathology最新文献

Research highlights: This study conducted an experiment on chicken infection with rotavirus A (RVA) strains.Two wild bird-derived RVA strains (RK1 and PO-13) caused diarrhoea in young chickens.The enteropathogenicity of these strains was comparable to that of a chicken strain.The findings indicate the risk of wild bird-derived RVAs in the poultry industry.

Newcastle disease (ND), caused by Newcastle disease virus (NDV), has posed a continuous threat to Iran's poultry industry since its first detection in the early 1950s, with subgenotype VII.1.1 currently recognized as the dominant circulating strain. To gain deeper insights into the evolutionary dynamics of NDV in Iran, we performed genome sequencing and phylogenetic analysis on 60 viruses isolated from domestic poultry and wild birds between 2017 and 2024. Maximum likelihood and Bayesian phylogenetic analyses of the fusion (F) and haemagglutinin-neuraminidase (HN) genes revealed that all viruses belong to subgenotype VII.1.1, forming a well-supported monophyletic group, indicative of independent evolution of this subgenotype within Iran after its introduction. The F and HN genes displayed high sequence identities of over 97% and 93%, respectively. All viruses contained a polybasic cleavage site in the F gene (R-R-Q/K-K-R↓F), consistent with virulent NDV strains. The estimated evolutionary rates for the F and HN genes were 1.31 × 10^-3 and 9.62 × 10^-4 substitutions/site/year, respectively. The most recent common ancestor of the subgenotype VII.1.1 F gene was dated to 2007 (95% highest posterior density: 2005-2009), likely originating from the Middle East. Bayesian skyride analysis showed an exponential increase in viral diversity between 2020 and 2024. Continuous surveillance of NDV in both poultry and wild birds in Iran is essential to track ongoing viral evolution, monitor potential changes in virulence or transmissibility, and identify emerging threats to poultry health and production.

Research highlights: Commercial inactivated vaccines improved the clinical picture of H5N1 in challenged birds.The developed vaccines induced protective antibody titres against HPAIV clade 2.3.4.4b within 4 weeks.The developed vaccines provided full protection against challenge by HPAIV clade 2.3.4.4b.The developed vaccines provided a significant reduction in virus shedding.

The circulating serotypes/genotypes of avian infectious coryza (AIC) in Iran have not been fully characterized, and disease control in layer and breeder flocks largely relies on imported vaccines. Given the correlation between genotypes and serotypes based on the previously proposed genotyping method, this study aimed to determine the genotypes of 28 Iranian Avibacterium paragallinarum isolates collected over a 7-year period (2018-2025), using sequences of region 1 and the hypervariable region (HVR) of the HMTp210 gene. PCR amplification of both regions was performed, and the resulting sequences were analysed alongside reference strains retrieved from GenBank. Two datasets were generated: one based on region 1 (aligned with the Page serotyping scheme) and the other based on concatenated sequences (corresponding to the Kume scheme). Phylogenetic analysis identified five previously known genotypes (I, II, VI, VIII, and IX), corresponding to serovars A-1, A-2, C-4, C-3, and an undetermined Kume serovar, in 24 isolates. Notably, two isolates (AP-20 and AP-28) formed distinct, well-supported phylogenetic clusters and were designated as novel genotypes XV and XVI, respectively. The HMTp210 HVR could not be amplified in two additional isolates (AP-17 and AP-18); however, analysis of their region 1 sequences indicated a close relationship to United States non-pathogenic strains. These findings suggest that the currently proposed genotyping scheme may be inadequate for classifying non-pathogenic strains. The circulation of multiple genotypes in Iran underscores the need for continued surveillance and re-evaluation of currently used vaccines, as effective control of AIC requires serotype-specific bacterins in vaccination programmes.

Research highlights: First complete genome sequencing of a DHAV-3 strain from Egypt using m-NGS.Discovery of a novel duck astrovirus co-infecting with DHAV-3.Phylogenetic analysis reveals cross-border transmission links with Asian strains of both DHAV-3 and DAstV-5.

Research highlights: Identified 26 antibiotic resistance genes, including novel plasmid IncI1-(α) never described in Salmonella Gallinarum.Revealed 107 virulence genes and multiple complete SPIs like SPI-1 and SPI-2.SNP analysis suggested reversion to virulence in eight vaccine-related strains.

This paper describes the investigation of the epidemiology of fowl adenoviruses (FAdVs) among fast-growing meat-type breeder parent chickens in Sweden, based on serology, PCR and partial genome sequencing of samples collected during rearing and egg production. Blood samples (n = 1910) from breeder flocks at 16 (79 flocks), 24 and 36 (52 flocks) weeks of age were analysed for FAdV antibodies. Ninety-four percent of the flocks had seroconverted at 16 weeks of age, and at 36 weeks of age all 52 flocks were seropositive. From 35 of these flocks, dead-in-shell chicks (DIS, n = 949) from eggs laid at 26-27 and 36-37 weeks of age were sampled, and pooled liver and caecal tonsils were analysed by PCR. Nucleic acid from FAdV was not detected. Negative PCR results were confirmed by testing tissues from 62 broiler breeders and 80 DIS from four additional seropositive flocks, collected at age 24-26 weeks. From six other breeder flocks, liver and caecal tonsils were sampled from one bird (when available) per day during rearing from 1-112 days of age. From 6 weeks of age, in 4/6 flocks, FAdV species A and/or D were detected by PCR and partial hexon gene sequencing. In conclusion, FAdVs were detected during rearing in breeder birds but not in DIS. This suggests that vertical transmission of FAdVs was prevented by immunity acquired early in life. However, it should be noted that high antibody titres in breeder birds does not necessarily confer protection against vertical transmission.RESEARCH HIGHLIGHTS The majority of 16-week-old parent flocks were seropositive to FAdV.FAdV was not detected by PCR in dead-in-shell chicks from seroconverted flocks.FAdV-A and D were detected in broiler breeders during rearing from 6 weeks of age.Results suggest that vertical spread was prevented by immunity in breeder birds.

Avian herpesviruses (AHVs) are widely distributed and associated with a variety of diseases affecting bird populations globally. Despite the increasing detection of AHVs in recent years, there remains a significant gap in knowledge regarding their classification and host range. This study aimed to detect herpesvirus (HV) in two vulnerable, endemic subspecies of stone-curlew (Burhinus oedicnemus) in the Canary Islands. Forty-six pooled tissue swabs (liver, kidney, and lung) and 135 individual swabs (brain, cloaca, and oropharyngeal cavity) were collected from 50 stone-curlews recorded as deceased wildlife specimens between 2020 and 2023. DNA from a novel alpha-HV was successfully amplified from seven out of the 181 tissue samples (4%) and from four out of 50 birds analysed (8%) using a semi-nested polymerase chain reaction (PCR) approach with degenerate primers. Positive samples were distributed across various tissue types: brain (n = 1), kidney (n = 1), lung (n = 2), coelomic cavity (n = 1), and oropharyngeal swab (n = 2). Some individuals tested positive in multiple tissue types, although no histopathological features indicative of HV infection were observed in any of the birds. Sequencing of all positive samples revealed identical HV nucleotide sequences across all specimens. The longest PCR amplicon, obtained with the TGV and KG1 primer combination, yielded identical sequences in two of the seven positive samples. Based on these findings, we propose the designation of this novel HV as Burhinus oedicnemus alphaherpesvirus.

Field observations suggest genotype-associated differences in susceptibility to infection with Enterococcus cecorum (EC). We hypothesized that slow-growing (SG) chickens show less clinical signs and reduced lesions compared to fast-growing (FG) chickens after experimental challenge with EC. At 1-day post-hatch (dph), 97 FG and 97 SG chickens were randomly assigned to four groups: control, SG (CSG), control, FG (CFG), EC-inoculated, SG (ESG), and EC-inoculated, FG (EFG). After oral inoculation with 10⁷ colony forming units EC or mock inoculation with physiological saline, chickens were monitored for clinical signs and samples were collected weekly for further analysis via ELISA, real-time PCR, and flow cytometric analysis. The final necropsy of 40 chickens per group was carried out at 43/44 dph. Clinical signs and pathological findings were observed in a reduced number of chickens in group ESG compared to EFG. Extra-intestinal colonization with EC at 43/44 dph was significantly reduced in group ESG compared to EFG (P < 0.05). Circulating heterophils and monocytes were significantly increased in groups ESG and EFG compared to the control groups (P < 0.05). Additionally, circulating monocytes were increased and heterophil/lymphocyte (H/L) ratios were decreased in SG chickens compared to FG chickens. We may speculate that SG chickens were less affected by the EC-associated disease due to a more efficient innate immune response and may more vigorously control extra-intestinal colonization after translocation from the intestine. Overall, the use of slow-growing chickens may reduce the incidence of the EC-associated disease in meat-type chickens and therefore increase overall health performance.

Gyrovirus homsa2 (GyVh2), originally identified in Tunisian children with diarrhoea, was previously known as Gyrovirus 6. In this study, chickens from 36 poultry farms across four major poultry-producing provinces in China (Henan, Hubei, Anhui, and Jiangsu) were screened for GyVh2 using polymerase chain reaction (PCR) from 2022-2024. As a result, 12 farms positive for GyVh2 were detected and subsequently subjected to whole-genome sequencing for GyVh2. The genomes of the 12 GyVh2 from positive farms were all 2282 nucleotides (nt) in length. Sequence similarity analysis showed high similarity (94.87%-99.65%) among the obtained and reference GyVh2 strains with no significant determining effect of years or geographic distribution, but low similarity (48.99%-57.60%) with other Gyrovirus species (Gyrovirus chickenanemia, Gyrovirus galga1, Gyrovirus galga2 and Gyrovirus homsa1). Phylogenetic analysis of the whole genome sequences of all 12 GyVh2-positive farms revealed that they formed a unique branch, clearly separated from other Gyrovirus species. Recombination analysis suggested that HN220604 (accession no.: PQ519595.1) and HN221228 (accession no.: PQ519596.1) may have originated from recombination with the human-derived GyVh2 strain (accession no.: NC_022789.1). A hypervariable region (located at sites 140-152) and highly mutated sites at positions 149, 254 and 380 were identified in the capsid protein through amino acid mutation analysis. The observed association between GyVh2 cross-species transmission and complex mutations and recombination offers a basis for future studies on its molecular epidemiology and evolution.