日本血吸虫肌动蛋白cDNA的克隆表达及其免疫保护功能

根据曼氏血吸虫肌动蛋白cDNA SmAct2设计一对引物，以日本血吸虫中国大陆株成虫mRNA为模板，用RT－PCR法扩增出一大小为1131bp的cDNA片段，测序后分析序列推断该片段为编码肌动蛋白基因的完整阅读框cDNA，与SmAct2 cDNA序列同源性为92％。该其克隆到载体pET28a( )中，在大肠杆菌BL21中获得了较高量的表达，融合表达产物分子量约为43kDa。利用日本血吸虫成虫粗抗原免疫大白所得抗血清对该表达产物进行Western印迹检测，在预测位置出现了明显的识别条带，说明所克隆的cDNA表达产物具有良好的抗原性。用该表达产物免疫昆明系小鼠，攻击血吸虫尾蚴以进行保护性实验。结果 其减虫率为28.4%，减卵率为29.2%，初步结果显示血吸虫肌动蛋白具有一定的免疫保护功能。

CLONING,EXPRESSING AND PROTECTIE IMMUNITY EVALUATING OF ACTIN cDNA OF SCHISTOSOMA JAPONICUM

A 1 131bp cDNA fragment was amplified by RT-PCR from adult Schistosoma japonicum(Chinese strain)mRNA with primers designed according to published SmAct2 encoding actin Sequence analysis indicated that this fragment, named SjAct,with 92% homology to SmAct2,was a ORF of cDNA encoding actin of Schistosoma japonicum (Chinese strain) This fragment was cloned into the expression vector pET28a( ) and subsequently expressed in Escerichia coli SDS-PAGE revealed that the molecular weight of this expressed product(rSjAct) was around 43kDa Western Blot showed that the recombinant protein had good antigenicity when probed with the rabbit serum against S japonicum(S j) worm antigens In order to evaluate the protective efficacy induced by this recombinant protein,Kunming mice were vaccinated 3 times with rSjAct and then challenged with 40 cercariae of S j The mice were perfused 7 weeks post-infection The reduction rate of worm and egg count per gram liver in vaccinated mice was 28 4% and 29 2% respectively The preliminary results showed that the rSiAct induces the significantly protection in vaccinated animals