Research Of Icterohaemorrhagiae Leptospira Genotyping

Leptospirosis, caused by pathogenic leptospira species, is a zoonosis throughout the world, especially in tropical areas. China is one of the most damaged countries by Leptospirosis, and several pandemics had happened in history. There are two classification systems for leptospira strains:serotyping and genotyping. Serotyping, with serotype as the basic systematic unit, is based on antigenic determinants, related to the lipopolysaccharides (LPS) present in the bacteria’s outer membrane. There are at least250serovars belonging to24serogroups have been identified. Icterohaemorrhagiae and Pomona are the dominant serogroups frequently associated with leptospirosis in China. The microagglutination test (MAT) and cross agglutination absorption test (CAAT) are the reference methods of serological identification. Identification of strains by serotyping, is less used because it needs a large number of standard reference strains, and the procedure is laborious and time-consuming. Genotyping is a classification based on DNA relatedness. With the development of molecular typing methods, some have been used for leptospira genotyping, such as amplified fragment length polymorphism (AFLP), pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and multiple locus VNTR analysis (MLVA), etc.The objectives of this study were to compare the results of genotyping by PFGE, MLVA and MLST, to find out the dominant strains, and the relationship of serotyping and genotyping, and find the effective prevent strategy of leptospirosis in China.We found that PFGE had a better discriminative power than MLVA and MLST. And MLVA is a simple molecular technique that does not require large quantities of DNA. It is suitable for fast diagnosis. The analysis by MLST could be successfully used to gain insights into the evolution and phylogeographic affinities of leptospires. The dominant strains are different between various areas.The complete genome sequencing of the serotype strain Lai belonging to serogroup Icterohaemorrhagiae has been reported by some Chinese scientists in2003. And later, the genome features of interrogans serovar Copenhageni (strain Fiocruz L1-130) was also reported. To understand the genome features of the species deeply, we developed a study with Shanghai JiaoTong University. And our aim was to have17standard conference strains of serogroup Icterohaemorrhagiae whole genome sequenced.