title: Genome reduction in Leptospira borgpetersenii reflects limited transmission potential.
abstract: Leptospirosis is one of the most common zoonotic diseases in the world, resulting in high morbidity and mortality in humans and affecting global livestock production. Most infections are caused by either Leptospira borgpetersenii or Leptospira interrogans, bacteria that vary in their distribution in nature and rely on different modes of transmission. We report the complete genomic sequences of two strains of L. borgpetersenii serovar Hardjo that have distinct phenotypes and virulence. These two strains have nearly identical genetic content, with subtle frameshift and point mutations being a common form of genetic variation. Starkly limited regions of synteny are shared between the large chromosomes of L. borgpetersenii and L. interrogans, probably the result of frequent recombination events between insertion sequences. The L. borgpetersenii genome is approximately 700 kb smaller and has a lower coding density than L. interrogans, indicating it is decaying through a process of insertion sequence-mediated genome reduction. Loss of gene function is not random but is centered on impairment of environmental sensing and metabolite transport and utilization. These features distinguish L. borgpetersenii from L. interrogans, a species with minimal genetic decay and that survives extended passage in aquatic environments encountering a mammalian host. We conclude that L. borgpetersenii is evolving toward dependence on a strict host-to-host transmission cycle.
authors.affiliation: Australian Bacterial Pathogenesis Program, Victorian Bioinformatics Consortium, Department of Microbiology, Monash University, Victoria 3800, Australia.
authors.forename: Dieter M
authors.initials: DM
authors.lastname: Bulach
authors.forename: Richard L
authors.initials: RL
authors.lastname: Zuerner
authors.forename: Peter
authors.initials: P
authors.lastname: Wilson
authors.forename: Torsten
authors.initials: T
authors.lastname: Seemann
authors.forename: Annette
authors.initials: A
authors.lastname: McGrath
authors.forename: Paul A
authors.initials: PA
authors.lastname: Cullen
authors.forename: John
authors.initials: J
authors.lastname: Davis
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnson
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kuczek
authors.forename: David P
authors.initials: DP
authors.lastname: Alt
authors.forename: Brooke
authors.initials: B
authors.lastname: Peterson-Burch
authors.forename: Ross L
authors.initials: RL
authors.lastname: Coppel
authors.forename: Julian I
authors.initials: JI
authors.lastname: Rood
authors.forename: John K
authors.initials: JK
authors.lastname: Davies
authors.forename: Ben
authors.initials: B
authors.lastname: Adler
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002417:Cattle; D002876:Chromosomes, Bacterial / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics; D018562:Disease Transmission, Infectious; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics*; D023281:Genomics; D006801:Humans; D007919:Leptospira / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D007921:Leptospira interrogans / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D012093:Replicon / Q000235:genetics; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D008565:Membrane Proteins