Comparative Analysis of Plasmid DNAs from Two Strains of Photobacterium damselae subsp. piscicida Isolated from Japan and the United States

Abstract

― Pseudotuberculosis pathogen, Photobacterium damselae subsp. piscicida ( Pdp ) shows some differences in virulence between Japanese and US strains. In this study, we analyzed plasmid DNAs derived from Japanese and US strains of Pdp , and found two homologous regions in these plasmids, pOT-51443-4/p91-197-1 and pOT-51443-1/p91-197-2. All genes in the p91-197-1 from US strain were observed in the pOT-51443-4 from Japanese strain. This event might have occurred during transmission of the US plasmid to Japanese strain. Inhibitor of vertebrate lysozyme ( ivy ), a known pathogenicity factor was encoded in the homologous region of pOT-51443-1/p91-197-2. Thus, the genomic region containing ivy may have been horizontally transmitted between the two Pdp strains.