Virulence Plasmids in Edema Disease: Insights from Whole-Genome Analysis of Porcine O139:H1 Shiga Toxin-Producing Escherichia coli (STEC) Strains
This study delves into the characterization of the plasmid sequences in genomes from isolates of porcine O139:H1 Shiga toxin-producing Escherichia coli (STEC) causing the Edema Disease (ED). We conducted whole-genome analysis to understand the role of these plasmids in the development of ED and their provenience. Our findings highlight the importance of plasmid pW1316-2 in the pathogenesis of ED, which carries key virulence genes. These genes include those encoding hemolysin toxins (hlyA and hlyB), which play a significant role in the cytotoxic effects observed in the progression of ED, as well as adhesion mechanisms (aidA-I, faeE), which are essential for host colonization. Furthermore, the detection of a plasmid related to that described in Shigella flexneri 2a provides insights into potential interactions among virulence genes present in different plasmids, particularly concerning the Hha-H-NS complex, which plays a pivotal role in regulating the production of a-hemolysin. Additionally, the identification of plasmid pB71 introduces a novel dimension to the virulence and resistance profiles of O139:H1 STEC strains, raising concerns about the dissemination of antibiotic resistance in pig farming, supported by our finding of tetracycline resistance genes tetA, tetC, and tetR on this plasmid. Overall, this study highlights the critical implications of virulence plasmids in ED pathogenesis, underscoring the importance of continued research for both swine industry management and public health protection.