Functional Expression Of Dipeptidyl Peptidaseâ…£ And Analysis Virulence Of Its Insertional Mutant In Streptococcus Suis Serotype 2

Streptococcus suis serotype 2 (SS2) is an important pathogen, thatcause meningitis, septicemia, arthritis, and pneumonia. So far, Themechanisms by which SS2 invades and infects the host are still unclear.To seeking and identification of new virulent agents and factors, weprokaryotic expressed the enzyme activity DPPIV in SS2 virulent strain05ZYH33. The amino acid sequence contained the sequenceGly-X-Ser-X-X-Gly, which is a consensus motif shared by S15 familygrouped in the SC clan of serine peptidases, Under the optimaltemperature at 37℃, and optimal pH at 6.5-8.5, DPPIV is a highlyspecific protease that cleaves after the X-Pro residues at the N terminus ofpolypeptide chains. Western blotting demonstrated that DPPIV reactsstrongly with convalescent-phase sera from pigs clinically infected bySS2, For detection DPPIV protein was present in the 05ZYH33 strainsurface, we developed an assay based on FCM assay, To test itsprevalence in SS, PCR assay was adopted to address the coding genessystematically. A soluble form of DPPIV protein was then used as acapture antigen to develop an enzyme-linked immunosorbent assay method to detect antibodies against SS2 in convalescent pig sera.To further research the function of DPPIV in adhension, the insertion mutant of DPPIV gene was constructed by allelic replacement. A reduction the virulence of the DPPIV mutant compared to wild strain in animal model systems of infection, which laid the foundation for the further Pathogenesis.