[ODP-102/W6-7] Roles of outer membrane components for the leptospiral motility on the kidney cells
Leptospira interrogans is a pathogenic spirochete, causing worldwide zoonosis, leptospirosis in various mammals. The spirochete colonizes the kidneys of the maintenance natural hosts and animals recovered from acute infection and is shed into environments upon urination. Animal experiments have suggested that leptospiral pathogenicity somehow involved motility. Our recent studies showed that Leptospira adhesion to the cultured cells and their persistent movements on the surface called crawling were relevant to the severity of the resultant symptoms. To understand its molecular mechanism, we investigated the effect of the lack of several outer membrane components (OMCs) on the crawling motility over cultured animal kidney cells. Implementation of the background-subtraction method into the image-analysis program allowed us to track the bacterial position without fluorescent labeling. We compared the adhesion and crawling of mutants lacking OMCs (LipL32, LenA, or LigA), obtained by transposon random mutagenesis, with those of the wild-type strain under a dark-field microscope. We found that lack of LenA or LigA shortened the persistent migration by crawling on the cell surfaces, whereas that of LipL32 did not affect the motility. The results suggest the responsibility of OMCs for the leptospiral motility on the host tissue, though their contributions are possible to be varied.