Résumé
Objective To construct the typeⅢ secretion system (T3SS) deficient mutant of O157∶H7 EDL933, and to detect its ability of attachment after infection with HeLa cells.Methods The recombinant DNA fragments obtained kana-mycin resistant gene were constructed by overlap extension PCR and transferred into EDL933/pKD46 to replace escR gene by homologous recombination.Results The T3SS-deficient mutant (ΔescR) was successfully construted.Compared with the wild-type EDL933, the growth rate and attachment on HeLa cells of ΔescR were significantly decreased.Conclusion The deletion of escR gene, which encodes T3SS structural protein EscR, affects the attachment of EDL933, suggesting a better basis for future studies of T3SS.
Résumé
Objective To construct a prokaryotic plasmid expressing the recombinant protein of enterohemorrhagic Escherichia coli(EHEC) effector NleB1 and to prepare the polyclonal antibody of mouse anti-NleB1.Methods The nleB1 (990 bp) gene was amplified from the genome EHEC O157∶H7 and cloned into the expression plasmid pET24a to construct the recombinant plasmid pET24a-nleB1 that was transformed into E.coli BL21(DE3).After induction with isopropylthio-gelactoside( IPTG) , the His-tag fusion proteins were purified by Ni+affinity chromatography and gel slices.The polyclonal antibody was prepared by immunizing BALB/c mice with purified recombinant proteins and analyzed by Western blotting and ELISA.Results The pET24a-nleB1 recombinant plasmid was successfully constructed, the fusion protein was ex-pressed and purified,and the polyclonal antibody was obtained by immunizing mice with purified fusion protein.Western blotting and ELISA staining demonstrated that the polyclonal antibody was successfully obtained.Conclusion The prepara-tion of the polyclonal antibody against EHEC O157∶H7 NleB1 will be of help for further studies on the function of NleB1 protein.