Abstract:ABSTRACT: In order to study the role of recombinant SSU05_1000 protein on the regulation of tight junctions, SSU05_1000 gene was amplified using the primers designed according to 05ZYH33 genome sequences and cloned to the expression vector pET30a to construct recombinant plasmid. The plasmid was transformed into E.coli BL21 (DE3) and induced to express by IPTG. The recombinant protein was purified by nickel affinity chromatography. Results showed that the recombinant expression plasmid could be highly expressed in E.coli and the purity of recombinant SSU05_1000 protein was above 90%. The purified protein was then treated with Triton X-114 to remove the contamination of endotoxin. Then, the human brain microvascular endothelial cells(hCMEC/D3) was treated by SSU05_1000 for different time and tested the expression of tight junctions by Western blot. The Western blot results show that SSU05_1000 could down-regulate the expression of tight junction protein Claudin-5 in hCMEC/D3, which indicates that SSU05_1000 protein might play important role on the traversal of S.suis across the human blood-brain barrier.