Tugce Serim Kanar

This study investigated the molecular characteristics and genetic diversity of Fowl adenovirus (FAdV) strains circulating in commercial broiler and layer flocks in the Southern Marmara and Aegean regions of Türkiye between January and December 2025. Liver samples (n = 120) collected from twelve flocks with increased mortality and clinical signs compatible with adenoviral infection were analyzed. Detection was performed using circular amplification technology and PCR targeting the hexon L1 region, and positive samples were sequenced for molecular characterization. BLAST analysis showed that all isolates belonged to Aviadenovirus hepatitidis and were identified as serotype 8b. Pairwise comparisons showed high nucleotide identity among isolates (97.4–100%) and 98.1–100% similarity with the Turkish reference strain MK937075. Only three isolates displayed nucleotide substitutions, while most sequences were identical within the analyzed region. Amino acid similarity ranged from 95.2% to 100%. Phylogenetic analysis revealed that all isolates clustered within a single monophyletic group together with previously reported Turkish FAdV-8b strains. Necropsy findings included hepatomegaly, multifocal hepatic pallor, petechial hemorrhages, gizzard erosion, and serous pericardial involvement. The detection of genetically closely related isolates across multiple provinces suggests regional circulation of a common viral lineage. These findings demonstrate that FAdV-8b is currently the predominant serotype associated with inclusion body hepatitis outbreaks in this major poultry production area and highlight the importance of molecular surveillance and targeted control strategies, including breeder monitoring and region-specific vaccine development.

Avian Infectious Bronchitis Virus (IBV) is a highly contagious Gammacoronavirus that poses a significant threat to the global poultry industry. Despite its worldwide prevalence, a critical knowledge gap exists regarding the genetic diversity of IBV in Central Asia, particularly in Uzbekistan. This study is the first comprehensive molecular characterization of IBV in Uzbekistan. This study also provides a unique and informative bioinformatic analysis of the detected strains. Three IBV strains were isolated and identified from chickens suspected of IBV infection. The isolates were identified and subjected to S1 gene sequencing, phylogenetic analysis, recombination screening, selective pressure mapping, and in silico structural and antigenic profiling. Phylogenetic inference revealed that the isolates clustered within the established genotypes GI-1, GI-13, and GI-23. Comparative alignments revealed distinct nucleotide and amino acid substitutions relative to global reference strains. The evolutionary patterns are consistent with a predominantly clonal mode of evolution. Structural modeling and B-cell epitope prediction revealed pronounced antigenic and topological divergence among the Uzbek isolates. Genotype-specific substitutions, particularly in solvent-exposed regions of the spike protein, were associated with altered epitope profiles, implying potential impacts on vaccine cross-protection. These findings contribute to current knowledge of IBV molecular characterization and provide the first reference framework for the Central Asian region. The study highlights the importance of continuous molecular surveillance, region-specific vaccination strategies, and integrated genomic monitoring for novel IBV variants.

This study aimed to detect possible viral agents in backyard poultry where numerous commercial poultry companies are located. The backyard flock had non-vaccinated 30 meat-type chickens and four turkey pullets. Serum samples and tracheal swabs were taken from chickens and turkey pullets showing respiratory signs. Serum antibody levels were measured using commercial ELISA kits against Avian Influenza Virus (AIV), Newcastle Disease Virus (NDV), Infectious Bronchitis Virus (IBV), Avian Metapneumovirus (AMPV), Mycoplasma gallisepticum (MG), Mycoplasma synoviae (MS), and Ornithobacterium rhinotracheale (ORT). In addition, tracheal swabs were tested for AIV serotypes H5, H7, and H9, NDV, IBV, AMPV, MG, MS, Pasteurella multocida, Avibacterium paragallinarum, and Bordetella avium by circular amplification technology (CAT). Anti-MS, -IBV, -MG, -NDV, -AMPV, and -ORT IgG antibodies were detected in some chicken sera, while anti-NDV, -MG, -MS, and -ORT IgG antibodies were detected in turkey sera. All avian tracheal swabs were positive for MG; however, IBV was only detected from chicken tracheal samples by CAT. The IBV strains were genotyped by sequencing a part of the S1 glycoprotein gene. Two isolates showed 99.35% and 98.69% nucleotide and 99.02% amino acid similarities with the 4/91 IBV strain. Two strains showed 99.35% nucleotide and 100% amino acid sequence identity to each other. Turkeys and chickens in the flock had MG and MG/IBV co-infections, respectively. Consequently, the presence of mutants of 4/91 IBV genotypes and MG found in backyard poultry could be a potential epidemiological source for commercial flocks in poultry integrations.