Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/4/2006
Publication Date: 9/14/2006
Citation: Bulach, D., Zuerner, R.L., Wilson, P., Seemann, T., Mcgrath, A., Cullen, P., Davies, J., Kuczek, E., Alt, D.P., Peterson-Burch, B. 2006. Genome reduction in Leptospira borgpetersenii reflects limited transmission potential. Proceedings of the National Academy of Sciences. 103(39):14560-14565. Interpretive Summary: Leptospirosis causes significant economic loss in the livestock industry through reproductive failure and reduced milk production. The bacteria that cause this disease can also cause disease in humans and companion animals. Vaccines to prevent infection have limited ability to provide protection against infection by these diverse bacteria. To understand more about the biology of the bacteria responsible for bovine leptospirosis, we sequenced the genomes of two strains of Leptospira. Genes that encode potential vaccine candidates were identified, and new information on how these bacteria may cause disease was obtained through detailed examination of the genome sequence data. This study establishes a foundation for further study and development of new ways to treat and prevent leptospirosis.
Technical Abstract: Leptospira borgpetersenii causes leptospirosis, a common zoonotic disease with global distribution. Leptospira is a diverse species, with several pathogenic species, with most human and animal cases of disease occuring from infection with L. borgpetersenii or L. interrogans. These bacterial species vary in their distribution in nature and may rely on different modes of transmission. We report the complete genomic sequence of two strains of L. borgpetersenii serovar Hardjo that have distinct phenotypes and pathogenicty, and compare the respective genetic content to develop a better understanding of the biology of pathogenic Leptospira spp. Although the genetic content of these two strains is nearly identical, differences in gene function through the development of pseudogenes and the occurance of non-conservative point mutations likey have a great impact on phenotype. Gene disruption by insertion sequences contributes to gene loss, and extensive rearrangements have generated unique patterns of genetic organization relative to L. interrogans. Thus, the L. borgpetersenii genome appears to be in a state of decay, with substantial loss of function in genes associated with environmental sensing and solute transport. These features distinguish L. borgpetersenii from L. interrogans, a species that can survive extended passage in aquatic environments before transmission to mammalian hosts, and suggest L. borgpetersenii may be evolving towards dependence on a strict host-to-host transmission cycle.