2型猪链球菌锌转运蛋白A对小鼠免疫保护作用

Immunoprophylaxis of ZnuA from Streptococcus suis 2 in mice

目的研究猪链球菌(Streptococcus suis,S.suis)锌转运蛋白A(ZnuA)对小鼠接种致死量2型猪链球菌(S.suis 2)菌株的免疫保护作用,为进一步研究S.suis 2亚单位疫苗奠定实验基础。方法采用聚合酶链反应(PCR)检测znuA基因在不同血清型S.suis中的分布情况;蛋白免疫印迹(western blot)检测ZnuA在S.suis 2的表达,利用流式细胞术对ZnuA进行细胞定位,动物实验研究ZnuA蛋白的免疫保护作用。结果除血清型17、21和30型菌株及荷兰分离株T15菌株外,其他30个血清型S.suis菌株、7996菌株以及3株S.suis 2型国内分离菌株基因组中均扩增到目的条带;S.suis 2菌体蛋白与兔抗ZnuA蛋白的血清能发生特异性反应;兔抗ZnuA血清标记S.suis 2的荧光强度明显较高;ZnuA重组蛋白免疫组小鼠死亡率较低。结论 ZnuA是一种具有免疫保护作用的蛋白,可作为S.suis的亚单位疫苗候选分子。

Objective To test the immunoprophylaxis of ZnuA in Streptococcus suis 2 （S. suis） and to provide experimental evidence for the study of sub-unit vaccine. Methods Based on the sequence of ZnuA of the Chinese strain 05ZYH33 of S. suis 2 ,the primers were designed and the target DNA fragment was amplified using the genomic templates of different serotypes of S. suis. Western blot was performed to detect the expression of ZnuA of S. suis 2. An assay based on flow cytometry（FCM） was developed to detect the localization of ZnuA on the surface of S. suis 2. Anaimal test was done to study the immunoprotection of ZnuA. Results The target DNA fragment was amplified in most serotypes of S. suis （except strains SS17,21,30 and isolated strain T15）. Fluoreseence-activated cell sorting（FACS） analysis and western blot showed that ZnuA localized on the surface of S. suis. Immunization with purified ZnuA could protect BALB/c mice against the challenge with a highly virulent S. suis 2 strain 05ZYH33. Condusion ZnuA could protect BALB/c mice against the challenge of a highly virulent S. suis 2 strain 05ZYH33 ,which suggests that ZnuA may be a candidate for the development of antibacterial protein sub-unit vaccine.