title: Molecular Typing of Pathogenic Leptospira Serogroup Icterohaemorrhagiae Strains Circulating in China during the Past 50 Years.
abstract: BACKGROUND
  Leptospirosis is one of the most important neglected tropical infectious diseases worldwide. Icterohaemorrhagiae has been throughout recent history, and still is, the predominant serogroup of this pathogen in China. However, very little in detail is known about the serovars or genotypes of this serogroup.
  
  
  RESULTS
  In this study, 120 epidemic strains from five geographically diverse regions in China collected over a 50 year period (1958~2008), and 8 international reference strains characterized by 16S rRNA sequencing and MLST analysis. 115, 11 and 2 strains were identified as L. interrogans, L. borgpetersenii, and L. kirschneri, respectively. 17 different STs were identified including 69 ST1 strains, 18 ST17, 18 ST128, 9 ST143 and 2 ST209. The remaining 12 strains belonged to 12 different STs. eBURST analysis demonstrated that, among the clonal complexes isolated (CCs), CC1 accounted for 73.3% (88/120) strains representing three STs: ST1, ST128 and ST98. ST1 was the most likely ancestral strain of this CC, followed by singleton CC17 (17/120) and CC143 (11/120). Further analysis of adding 116 serogroup Icterohaemorrhagiae strains in the MLST database and studies previously described using global eBURST analysis and MST dendrogram revealed relatively similar ST clustering patterns with five main CCs and 8 singletons among these 244 strains. CC17 was found to be the most prevalent clone of pathogenic Leptospira circulating worldwide. This is the first time, to our knowledge, that ST1 and ST17 strains were distributed among 4 distinct serovars, indicating a highly complicated relationship between serovars and STs.
  
  
  CONCLUSIONS
  Our studies demonstrated a high level of genetic diversity in the serogroup Icterohaemorrhagiae strains. Distinct from ST17 or ST37 circulating elsewhere, ST1 included in CC1, has over the past 50 years or so, proven to be the most prevalent ST of pathogenic leptospires isolated in China. Moreover, the complicated relationship between STs and serovars indicates an urgent need to develop an improved scheme for Leptospira serotyping.
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
authors.forename: Cuicai
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Mentougou District Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Huimian
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
authors.forename: Xiuwen
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Cao
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
authors.forename: Haijian
authors.initials: H
authors.lastname: Zhou
authors.affiliation: SiChuan Province Center for Disease Control and Prevention, Chengdu, People's Republic of China.
authors.forename: Linzi
authors.initials: L
authors.lastname: Zeng
authors.affiliation: JiangXi Province Center for Disease Control and Prevention, Nanchang, People's Republic of China.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Xu
authors.affiliation: Key Laboratory of the Ministry of Health for Research on Quality and Standardization of Biotech Products, National Institutes of Food and Drug Control, Beijing, People's Republic of China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
authors.forename: Yung-Fu
authors.initials: YF
authors.lastname: Chang
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Yongzhang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
authors.forename: Xiugao
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D006801:Humans; D007919:Leptospira / Q000145:classification* / Q000235:genetics*; D058885:Multilocus Sequence Typing / Q000379:methods*; D058069:Neglected Diseases / Q000469:parasitology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D065288:Serogroup; D012703:Serotyping; D014895:Weil Disease / Q000453:epidemiology*; D015047:Zoonoses / Q000469:parasitology*
chemical_list: D012336:RNA, Ribosomal, 16S