药桑提取物对猪链球菌溶血素活性的影响

Effects of Medicinal Mulberry Extract on Activity of Suilysin from Streptococcus suis

猪链球菌的致病力与其合成或分泌的各种毒力因子密切相关,其中猪链球菌溶血素(SLY)发挥着重要的作用,如脑膜炎等感染。因此筛选SLY抑制剂对于猪链球菌感染具有一定的意义。试验通过溶血试验和生长曲线测定等研究发现,较低浓度药桑提取物对猪链球菌生长几乎无影响,但可显著抑制猪链球菌溶血素介导的溶血活性。在猪链球菌与宿主细胞共培养体系内加入药桑提取物可明显抑制细菌穿透上皮细胞屏障及其介导的细胞毒性作用。结果表明:药桑提取物通过抑制SLY活性可体外降低猪链球菌毒力,是一种潜在的抗猪链球菌感染的先导复合物。

The virulence factors secreted by Streptococcus suis are associated with pathogenecity of this bacteria,such as suilysin （SLY）,which plays an important role in meningitis.Thus,targeting SLY would be a promising strategy for S.suis infection.In the present study,medicinal mulberry extract was found to directly,neutralize hemolytic activity of S.suis culture supernatants without affecting bacterial viability by hemolysis assay and determination of bacterial growth.The addition of medicinal mulberry extract into co-culture system of S.suis and host cells significantly inhibited the bacterial traversal across epithelial barrier and bacteria-mediated cytotoxicity.Thus,our results established that medicinal mulberry extract could inhibit SLY activity and decrease S.suis virulence in vitro,indicating that this compound may represent a lead compound for S.suis infection.