Virulence plasmids in edema disease: Insights from whole-genome analysis of porcine O139:H1 Shiga toxin-producing Escherichia coli (STEC) strains

This study investigates the plasmid sequences of porcine O139:H1 Shiga toxin-producing <i>Escherichia coli</i> (STEC) responsible for Edema Disease (ED). Whole-genome analysis reveals significant similarities between these strains and known plasmids, notably pW1316-2, which harbors key virulence genes like hemolysin (<i>hlyA</i>, <i>hlyB</i>) and adhesion factors (<i>aidA-I</i>, <i>faeE</i>). These genes contribute to the cytotoxicity and host colonization associated with ED. Additionally, similarities to plasmids from <i>Shigella flexneri</i> 2a highlight potential associations in virulence gene regulation, particularly via the <i>Hha-H-NS</i> complex. The identification of sequences resembling plasmid pB71 raises serious concerns about the emergence of highly pathogenic strains, as it includes tetracycline resistance genes (<i>tetA</i>, <i>tetC</i>, <i>tetR</i>). This research emphasizes the role of plasmid-like sequences in ED pathogenesis, indicating important implications for swine industry management and public health.