Speakers
Description
Avibacterium paragallinarum (A. paragallinarum) is the etiological agent of infectious coryza, a highly contagious respiratory disease that causes substantial economic losses in the global poultry industry through increased mortality and reduced egg production. The emergence of antimicrobial resistance (AMR), poses a severe threat to effective disease management. This study aimed to analyze the genetic diversity of aminoglycoside-resistant A. paragallinarum clinical isolates to elucidate the resistance mechanisms and evolutionary relationships. A total of 118 A. paragallinarum genome sequences were acquired from the BV-BRC database. In-silico screening using ABRicate with the ARG-ANNOT database was employed to identify aminoglycoside resistance genes, revealing the presence of APH(3′), APH(3″), APH(6), AAC(3), and ANT(3″) genes across various strains. Comprehensive genomic analyses were performed, including pangenome assessment with GET_HOMOLOGUES, phylogenetic reconstruction using Roary and maximum likelihood methods, and detailed variant calling to identify single nucleotide polymorphisms (SNPs), insertions, and deletions.The pangenome analysis revealed extensive genetic diversity, comprising 7,857 gene clusters, with only a single universal core gene, indicating a highly plastic and open genome. A significant number of genes were categorized as shell (4,595) and cloud (3,261), highlighting the role of accessory genes in adaptation and resistance. Phylogenetic analysis delineated distinct evolutionary clusters, suggesting potential lineage-specific adaptations linked to geographical origin and selective antibiotic pressure. Variant calling confirmed substantial genomic variations, including high SNP counts in resistant strains like AV25 and C-AP1. Crucially, the resistance gene profiling confirmed the widespread distribution of aminoglycoside-modifying enzymes (AMEs), which are responsible for enzymatic inactivation of the drugs, as a primary resistance mechanism.
This study provides a high-resolution genomic perspective on aminoglycoside resistance in A. paragallinarum.
Keywords: Avibacterium paragallinarum, Infectious Coryza, Aminoglycoside Resistance, Genetic Diversity, Antimicrobial Resistance (AMR).