牛源抗金黄色葡萄球菌α溶血素单链抗体研制

Construction of bovine single-chain antibody against α hemolysin of Staphylococcus aureus

由金黄色葡萄球菌引起的奶牛乳腺炎给养殖业造成了严重损失,抗生素是治疗奶牛乳腺炎的首选方法,但易出现耐药菌株。而目前针对金黄色葡萄球菌的疫苗也不能对奶牛乳腺炎提供足够的保护,疫苗的主要作用机理是激发机体产生抗体,故被动免疫针对金黄色葡萄球菌毒力因子的抗体也许能对感染起到一定的治疗作用。本研究首先扩增得到影响其致病性的重要毒力因子-α溶血素(Hla)的编码基因,然后将其转化到E.coli中进行表达并纯化,再以此纯化产物为抗原,从牛源噬菌体单链抗体表达文库中筛选到了一株针对α溶血素(Hla)高亲和力的scFv,最终将该scFv进行纯化。本研究一方面为治疗金黄色葡萄球菌所致奶牛乳腺炎提供一种新思路,另一方面也为分子水平上研究α溶血素的致病机制提供了有效的阻断分子。

Staphylococcus aureus -induced bovine mastitis has caused significant losses in the dairy industry.At present,antibiotics are primarily used for the treatment of S.aureus -induced mastitis,but this strategy can increase the prevalence of antibiotic-resistant bacterial strains.However,the current vaccines have not provided adequate protection against S.aureus infection in cattle.Therefore,passive immunization with antibodies against S.aureus virulence factors may be effective.In this study,α hemolysin(Hla) gene,which encodes the most important virulence factor in S.aureus infection,was firstly amplified,and transformed into E.coli for expression and purification.After three rounds of selection,one single-chain variable region fragment(scFv) that bound to Hla with high affinity was obtained from bovine scFv phage display library.Finally,the scFv was purified.For one thing,this study provides an effective blocking molecule for studying the pathogenesis of Hla at the molecular level;for another,it provides a therapeutic candidate for the treatment of S.aureus -induced bovine mastitis.