PCR-Based Detection of Horizontal Gene Transfer of iucA and ipaA Virulence Genes in Clinical E. coli Isolate EPT09 from Pakistan

2 Abstract: The pathogenic E. coli strains are very important public health issue, especially in developing countries. Among the dangerous aspects of these strains is the zoonosis and acquisition of new genes through horizontal gene transfer via mobile genetic elements like plasmids, viruses or transposons. These genes include Shiga toxin (Stx1, Stx2 or variants) genes. The aerobactin operon encodes iucA, B, C and D enzymes for the aerobactin synthesis and an outer membrane aerobactin receptor Iut. In some strains of E. coli and Salmonella the aerobactin genes are found on pColV and F1me plasmids, respectively. Moreover, these genes were reported to be located on chromosome in Shigella and other E. coli strains. In the present study plasmid profile assay of clinical E. coli isolate EPT09 showed three types of plasmids designated as pEPT1 (23.1kb), pEPT2 (1.3kb) and pEPT3 (0.85kb). All the clones of EPT09 showed same plasmid profile. PCR analysis showed no amplification of the virulence gene ipaA but iucA gene was detected on plasmid DNA in EPT09. The later is reported on chromosomal DNA in Shigella,. So results of present study suggest that clinical E.coli isolate "EPT09" obtained virulence gene iucA through horizontal gene transfer and was incorporated into the plasmid DNA.