奇异变形杆菌聚磷酸盐激酶多克隆抗体的制备和鉴定

Expression of Proteus mirabilis polyphosphate kinase and preparation of its polyclonal antibodies

目的表达、纯化奇异变形杆菌聚磷酸盐激酶(PPK)蛋白,制备PPK多克隆抗体。方法利用分子生物学软件分析奇异变形杆菌PPK的抗原性、疏水性等参数,选取N端较保守的309个氨基酸,并对其基因序列进行密码子优化以利于原核表达。合成新的基因序列后插入pET28b(+)质粒,转化入转化宿主菌BL21(DE3),诱导、表达融合蛋白。通过镍琼脂糖亲和层析技术,将获得的融合蛋白进行纯化。以纯化的蛋白作为免疫原并结合使用佐剂,背部多点注射新西兰大白兔,ELISA检测兔血清效价,Western Blotting验证抗体特异性。结果成功构建了奇异变形杆菌PPK的原核表达重组质粒,可在0.5 mmol/L IPTG、37℃条件下获得较好的诱导、表达;利用镍柱纯化后的PPK蛋白与免疫佐剂一起,采用背部多点接种新西兰大白兔,制备了效价高的兔抗血清。ELISA检测血清效价达到1∶512 000,Western Blotting对ppk基因缺失株及其野生株进行验证显示抗体特异性良好。结论利用pET28b(+)载体可构建奇异变形杆菌PPK的原核表达重组质粒,表达、纯化后的蛋白与佐剂共同免疫新西兰大白兔,可获得效价高、特异性良好的兔多克隆抗体血清,为奇异变形杆菌聚磷酸盐激酶的检测以及深入研究PPK在奇异变形杆菌致病中的作用奠定了基础。

Objective To express and purify polyphosphate kinase(PPK) from Proteus mirabilis and prepare the polyclonal antibody against PPK. Methods The antigenicity and hydrophobicity of PPK were analyzed using software. The N-terminal conservative sequence containing 309 amino acids was selected as the target peptide,and its corresponding gene sequence with modification based on prokaryotic cells-preferred codon was synthesized and inserted into plasmid pET28b(+). The constructed recombinant plasmid was transformed into Escherichia coli BL21(DE3) and induced with IPTG. The expressed fusion protein was purified using Ni-affinity chromatography. The purified protein was injected along with adjuvant in rabbits to prepare the polyclonal antibodies against PPK. Results and Conclusion PPK fusion protein expressed by E. coli was purified successfully using Ni-affinity chromatography. ELISA result demonstrated that the harvested rabbit anti-sera against PPK had a high titer of 1∶512 000,and Western blotting showed a good specificity of the antibody,which can be used further study of the role of PPK in the pathogenesis of Proteus mirabilis infection.