Genomic Characterization and Pathogenicity Island Analysis of 17 Mexican Isolates of Corynebacterium pseudotuberculosis biovar ovis.

Pathogenicity islands (PAIs) are regions of bacterial genomes that harbor genes encoding virulence factors. Identifying molecules that enhance pathogenicity is crucial for understanding the mechanisms pathogens employ to cause disease and their evolution. Corynebacterium pseudotuberculosis (C. pseudotuberculosis) is a pathogenic microorganism that causes caseous lymphadenitis (CLA) in sheep and goats. Despite its prevalence in Mexico, its genetic material has not been analyzed for virulence factors acquired through horizontal gene transfer. Therefore, the aim of this study was to characterize the complete genomes of Mexican C. pseudotuberculosis strains and identify virulence-related genes harbored with PAIs. Seventeen strains of C.pseudotuberculosis biovar ovis isolated from Mexico were whole-genome sequenced using illumina technology, assembled de novo with SPAdes, and annotated using Prokka. PAIs were predicted with GIPSy based on genomic signatures associated with horizontal gene transfer, including G + C deviation, codon usage, virulence factors, transposases, and tRNA-flanking regions. Positive selection was assessed using POTION v1.2 by identifying orthologous groups enriched in non-synonymous substitutions. This represents the first comprehensive PAI analysis of Mexican C. pseudotuberculosis strains, identifying 14 putative pathogenicity islands harboring 51 virulence-associated genes. Additionally, positive selection analysis identified five coding sequences, including radA and rpiB, that are undergoing adaptive evolutionary changes. These findings elucidate the pathogenic mechanisms and genomic plasticity of Mexican C. pseudotuberculosis strains. They also highlight novel genetic targets for vaccine and therapeutic development against CLA.