الفهرس Only 14 pages are availabe for public view
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Abstract
Ducks have an important role in the poultry industry especially in developing countries like Egypt. However, duck diseases received a little attention from the veterinary research as well as veterinarians. Riemerella anatipestifer is considered one of the most important threats for ducks and ducklings worldwide. In the present study, isolation and molecular characterization for R. anatipestifer based on PCR for full length outer membrane protein A (ompA), sequencing and phylogeny followed by prediction for the ligand binding sites on the surface of the immunogenic protein (OmpA). BLAST result for the obtained nucleotide sequences revealed the circulation of different serotypes among the Egyptian duck flocks indicating progressive adaptation and evolution of R. anatipestifer among ducks and ducklings. Phylogeny was conducted based on full length ompA gene that classifies the diversity of R. anatipestifer worldwide into two main lineages (lineage 1 and lineage 2); each lineage diversified into three main clusters based on the evolution studies and confirmed by 3D prediction. Till now, at least 21 R. anatipestifer serotypes had been identi{uFB01}ed. In spite of the molecular techniques regarding its pathogenicity and antigenicity, they are not well understood. This study reports the first genotyping of R. anatipestifer based on an immunogenic protein (OmpA) and confirm the co-circulation of different R. anatipestifer clusters in the Egyptian duck flocks. The isolates were belonging to lineage 1 (cluster I and II) and linage 2 (cluster I and III). These findings represent a start to what should be an expanded investigation of the genetic diversity of R. anatipestifer at national and regional levels to better understand evolution dynamics, distribution and the genetic relatedness among the duck industry. In conclusion, identifying the disease cause, source of infection, mode of transmission, and the immunogenic factors of R. anatipestifer is essential for its molecular characterization and analysis of virulence mechanisms as well as its prevention and control