Characterization Of Erysipelothrix Rhusiopathiae Pathogenicity And Identification Of Surface Protein Though MALDI-TOF-MS Analysis

Swine erysipelas is an ancient disease with a worldwide distribution. Erysipelothrix rhusiopathiae is the main causative agent of it and its special cell wall structure gives this bacteria unique infection style. E. rhusiopathiae is considered to be a threaten to farming industry and public health system for its adaptability.In this study, mice virulence test, complement resistance test and anti-phagocytosis experiment have been used to indentify pathogenicity of E. rhusiopathiae. Median lethal dose(LD50), serum sensitivity and anti-phagocytosis index are as measurement criteria. Results indicated that E. rhusiopathiae of S type have expressed strong virulence in mice virulence model. The LD50 of E. rhusiopathiae strain C43065 and strain C43311 is 81.59 CFU and 191.04 CFU separately. Groups with injected R type E. rhusiopathiae are all survival. Regard to the anti-phagocytosis index, E. rhusiopathiae of S type is more excellent than the opponent. In the experiment of serum sensitivity, reproduction rate of S type E. rhusiopathiae have not been effected, this is outstanding than the R type which have been decreased for one times lower.Phylogeny analysis of groEL gene,with 1614 bp, have encode a heat shock protein(HPS60) with 537 amino acid, have indicated that they have similarity of 99% with the sequence within genome of E. rhusiopathiae ATCC19414 and Erysipelothrix tonsillarum ATCC43339. The results of analysis for 16 S rRNA gene sequences expressed that similarity to E. rhusiopathiae ATCC19414 and ATCC43339 are both 99%. Computing result though maximum parsimony method of MAGA software expressed all four strains are belong to the species of E. rhusiopathiae. And the groEL gene has higher resolution as molecular target. Research work of Jones in Bergey’s manual of systematic bacteriology indicated that E. rhusiopathiae can be separated as S type and R type based on six features as bacteria body, colony size, surface character, transparency, color and colony edge. Results showed that E. rhusiopathiae strain of C43065 and C43001 which have powerful virulence are belong to S type and the other two are belong to R type without any virulence.To detecting the reason for virulence discrepancy of different type of E. rhusiopathiae strains, we have extracted and separated surface protein of E. rhusiopathiae C43065 strain, C43001 strain, C43309 strain and C43311 strain. And the further mass spectrum analysis have been processed though Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry(MALDI-TOF-MS) apparatus. 10 sorts of protein which is same as or similarity to the published virulence factor have been discovered. However, the differences on surface protein of four bacteria strains were undetected.Enzyme-Linked Immunosorbnent Assay(ELISA) can response antibody level within mice serum based on the specificity and sensitivity. It detected that the whole protein of S type E. rhusiopathiae can stimulate higher antibody level than R type. Be similar to these results, immunoprotection test expressed that whole protein of S type E. rhusiopathiae can produce completed immunoprotection and the immunoprotection ratio of E. rhusiopathiae C43309 strain and C43311 strain is only 60% and 70% respectively. Both of two results have verified that there exsits diversity in immunogenicity of two different types of E. rhusiopathiae.