Comparative genomic analysis of eight Leptospira strains from Japan and the Philippines revealing the existence of four putative novel genomic islands/islets in L. interrogans serovar Lai strain 56601.

Leptospirosis is one of the most widespread zoonotic diseases worldwide and can be considered an emerging health problem to both human and animal. Despite the importance of the disease, complete genome sequences are currently available for only three Leptospira interrogans strains: 56601, Fiocruz L1-130, and IPAV. Therefore, intra- and inter-species comparative genomic analyses of Leptospira are limited. Here, to advance current knowledge of the genomic differences within Leptospira species, next-generation sequencing technology was used to examine the genomes of eight L. interrogans strains belonging to six different serogroups isolated from humans and dogs in Japan and the Philippines. The genomic sequences were mapped to that of the reference strain, L. interrogans serovar Lai strain 56601. The results revealed the presence of four novel genomic islands/islets (GIs) in strain 56601. This study provides a deeper insight into the molecular basis and evolutionary perspective of the virulence of leptospires.