轮状病毒SA11衣壳蛋白VP7的毕赤酵母重组表达及IgY的制备

Cloning and expression of rotavirus SAll VP7 and preparation of IgY antibodies against recombinant VP7

目的真核重组表达轮状病毒（rotavirus，RV）SA11株VP7衣壳蛋白并制备、纯化其卵黄抗体（IgY）。方法将SA11标准株在MA104细胞中增殖，收集病毒液。从病毒液中提取RNA，通过逆转录聚合酶链反应（RT-PCR）扩增获得SA11株衣壳蛋白VP7的长度为978bp的编码基因，将PCR产物连接到pMD18-T载体上，进行测序。将重组体亚克隆到分泌表达载体pPICZαB中，再将重组体转化人大肠杆菌rop10中，用BstXI线性化酶切重组质粒后电转入毕赤酵母X-33中，进行测序。转染成功的菌落再用甲醇诱导表达，亲和层析法纯化重组蛋白抗原，十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS—PAGE）和蛋白免疫印迹（Western blotting）鉴定，用重组蛋白免疫罗曼母鸡，收集鸡蛋，Western blotting鉴定、纯化IgY。结果细胞增殖液中提取的RNA银染可见11个条带，成功构建了含pPICZαB—SAllVP7的毕赤酵母X-35，毕赤酵母X-33分泌的融合蛋白被收集、纯化。毕赤酵母X-33表达的SA11VP7的衣壳蛋白经Western blotting验证与预测蛋白相对分子质量40200相符。从鸡蛋中提取的鸡的IgV验证为抗Vfy7的抗体。纯度可达到95％，1个鸡蛋能产10．2mg的IgY。结论抗重组RVSA11衣壳蛋白VP7和IgY的成功制备为疫苗和诊断试剂的开发奠定了基础。

Objective To prepare eukaryotic expression of rotavirus （RV） SA11 capsid protein VP7, and to generate and purify yolk immunoglobulin （IgY） antibodies against the recombinant VP7 from Roman hens. Methods MA104 cells were infected with the standard SAI 1 strain and the culture fluid was collected. A DNA fragment of 978 bp encoding SAll VP7 was obtained by RT-PCR amplification from genomic RNA of RV SA11. The PCR products were ligated to pMD18-T vector following the confirmation by DNA sequencing and sub-cloned into pPICZαB. The recombinant pPICZαB-SA11 VP7 was transformed into E coli ToplO. The plasmids were linearized by digestion of BstXI and transformed into Pichia pastoris X-33 through electroporation by DNA sequencing. The transformants were induced with methanol for expression. The cultural supernatant was subjected to SDS-PAGE and Western blotting. Fusion expression was purified through the column of affinity chromatography. IgY was identified and purified by SDS-PAGE and Western blotting from eggs of Roman hens immunized with recombinant SA11 VP7. Results The RNA extracted from the RV culture fluid consisted of 11 bands visualized by silver staining. The expression vector pPICZαB-SAll VP7 was constructed and the fusion protein in Pichia pastoris X-33 was harvested and purified. The recombinant SAll VP7 with molecular weight of 40 200 was identified by Western blotting. The IgY antibodies against the recombinant SA11 VP7 were produced with a purity of 95 percent and yield of 10. 2 mg per egg. Conclusion The preparation of IgY antibodies to recombinant SAll VP7 might lay a foundation for the development of vaccines and diagnostic techniques.