利用噬菌体展示肽库筛选和鉴定沙门氏菌O9抗原的模拟表位

目的　用生物素标记沙门氏菌O9单克隆抗体 (3- 4 7-O)作为分子探针 ,从两个九肽噬菌体展示文库中筛选鉴定该抗体所识别的抗原模拟表位 ,从而为模拟多糖的多肽疫苗或编码该模拟表位的DNA疫苗研制奠定基础。方法与结果　经过三轮的亲和筛选 ,得到了两个能与O9单抗反应的强阳性单克隆扩增物gm6 2和 gm6 8,其序列分别为SHHVRGGGG和YQKWYLPKS。竞争ELISA实验表明 ,10 10转导单位噬菌体 gm6 8对肠炎沙门氏菌与 3- 4 7-O结合的抑制率达到 6 5 % ,而噬菌体 gm6 2的抑制率仅为 2 0 % ,且 gm6 8可以诱导产生针对沙门氏菌O9的抗体 ,而gm6 2则不能。 结论　实验结果显示九肽YQKWYLPKS是具有免疫原性的O9抗原模拟表位。

Screening and identification of an immunogenic peptide that mimics antigen O9 of Salmonella by using phage display libraries

Aim To screen minotopes from phage display libraries,named as pVⅢ 9aa and pVⅢ 9aa Cys,recognized by monoclonal antibody (MAb) 3 47 O which is specific for antigen O9 of Salmonella Methods and Results After three rounds of biopanning,two positive clones designated as gm68 and gm62 were identified and amino acid sequence YQKWYLPKS and SHHVRGGGG of two oligopeptides,were deduced respectively after DNA sequencing The phage clone gm68 blocked the binding of MAb 3 47 O to antigen O9 of Salmonella enteritidis, and the inhibition rate was higher than 65% by 10 10 transduction unit (TU) phages in competitive ELISA,while the inhibition rate of gm62 was only 20% And the phage clone gm68 induced ICR mice high level of antibody against antigen O9,while gm62 did not Conclusion The peptide YQKWYLPKS was an immunogenic minotope of antigen O9 with high specificity It would be very useful for the study pathogenesis and immune protection ofSalmonella antigen O9 and for developing anti carbohydrate peptide vaccines or DNA vaccines