title: Global transcriptomic response of Leptospira interrogans serovar Copenhageni upon exposure to serum.
abstract: BACKGROUND
  Leptospirosis is a zoonosis of worldwide distribution caused by infection with pathogenic serovars of Leptospira spp. The most common species, L. interrogans, can survive in the environment for lengthy periods of time in between infection of mammalian hosts. Transmission of pathogenic Leptospira to humans mostly occurs through abraded skin or mucosal surfaces after direct or indirect contact with infected animals or contaminated soil or water. The spirochete then spreads hematogenously, resulting in multi-organ failure and death in severe cases. Previous DNA microarray studies have identified differentially expressed genes required for adaptation to temperature and osmolarity conditions inside the host compared to those of the environment.
  
  
  RESULTS
  In order to identify genes involved in survival in the early spirochetemic phase of infection, we performed a transcriptional analysis of L. interrogans serovar Copenhageni upon exposure to serum in comparison with EMJH medium. One hundred and sixty-eight genes were found to be differentially expressed, of which 55 were up-regulated and 113 were down-regulated. Genes of known or predicted function accounted for 54.5 and 45.1% of up- and down-regulated genes, respectively. Most of the differentially expressed genes were predicted to be involved in transcriptional regulation, translational process, two-component signal transduction systems, cell or membrane biogenesis, and metabolic pathways.
  
  
  CONCLUSIONS
  Our study showed global transcriptional changes of pathogenic Leptospira upon exposure to serum, representing a specific host environmental cue present in the bloodstream. The presence of serum led to a distinct pattern of gene expression in comparison to those of previous single-stimulus microarray studies on the effect of temperature and osmolarity upshift. The results provide insights into the pathogenesis of leptospirosis during the early bacteremic phase of infection.
authors.affiliation: Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Kanitha
authors.initials: K
authors.lastname: Patarakul
authors.forename: Miranda
authors.initials: M
authors.lastname: Lo
authors.forename: Ben
authors.initials: B
authors.lastname: Adler
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001770:Blood Bactericidal Activity; D003470:Culture Media; D020869:Gene Expression Profiling / Q000379:methods; D015964:Gene Expression Regulation, Bacterial; D006168:Guinea Pigs; D007921:Leptospira interrogans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007922:Leptospirosis / Q000382:microbiology; D020411:Oligonucleotide Array Sequence Analysis; D009994:Osmolar Concentration; D012329:RNA, Bacterial / Q000032:analysis; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015610:Serum Bactericidal Test; D013696:Temperature; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D012329:RNA, Bacterial; D037521:Virulence Factors