Objective To construct the recombinant plasmid of PA-ⅠL and express in E.coli BL 21 (DE3), and evaluate the biological activity of recombinant protein.Methods PA-ⅠL gene was amplified by PCR using primers designed according to Pseudomonas aeruginosa genome sequences and then cloned to the vector pET -28a ( +).The recombinant plasmid was transformed into E.coli BL21(DE3) and induced to express by IPTG.The recombinant protein was purified by nickel affinity chromatography.The binding activity of recombinant PA-ⅠL with Gb3/CD77 was evaluated by flow cytometry.The function of recombinant PA-ⅠL on the binding of bacteria with host cells was evaluated by colony plate counting.Results and Conclusion The recombinant PA-ⅠL protein was highly expressed in E.coli BL21(DE3) and protein purity by SDS-PAGE analysis was high after nickel affinity chromatography .Besides, the recombinant PA-ⅠL had binding activity to Gb3/CD77 and inhibited the binding of PAO1 to host cells in a dose-dependent manner.

Objective To explore the interaction of streptococcus suis serotype 2 recombinant suilysin ( SLY ) with platelets, and provide the theoretical basis for clinic treatment of patients infected with S.suis.Methods The nickel column affinity chromatography was used to purify the recombinant SLY.The hemolytic acivity was identified by optical density before the platelets aggregation induced by a SLY was detected by a platelet aggregometer or electron microscope and the effect of aspirin on platelets aggregation was analyzed.The impact of wild type 05ZYH33 and sly-deficient mutant strainΔSLY on platelets of mice was compared to predict the interaction of the SLY with platelets in vivo.Results and Conclusion Hemolytic activity of recombinant SLY was 2000 hemolytic units( HU) and platelets aggregation was induced at 1 μg/ml.The aggregation can be inhibited by aspirin in 5 mmol/L.SLY can also increase the volume and reduce the amount of platelets in mice.