日本血吸虫中国大陆株21.7kD蛋白编码基因的克隆和表达

根据日本血吸虫菲律宾株编码21.7kD蛋白的基因设计引物，以日本血吸虫中国大陆株成虫mRNA为模板，用RT-PCR法扩增出大小为558bp的基因片段。经序列分析推断该基因片段为编码日本血吸虫中国大陆株21.7kD蛋白基因的完整阅读框，与菲律宾株该基因的碱基序列同源性为98%。将其克隆到表达载体pET28a(+)中，在大肠杆菌BL21中获得表达，融合表达产物分子量约为25.4kD。利用日本血吸虫成虫抗原免疫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，说明该基因的表达产物具有抗原性。

Cloning and Expression of 21.7kD Protein Gene of Sch istosoma japonicum(Chinese strain)

A 558 bp cDNA fragment was amplified by RT-PCR from adult Schistosoma japonicum(Chinese strain) mRNA with a pair of primers that were designed according to published Sj21.7p gene encoding 21.7 kD protein of Schistosoma japonicum(Philippines strain). Sequence analysis indicated that this frame, named Sj21.7(Ch), with 99% homology to Sj21.7p, contained a complete open reading fragment (ORF) of 21.7 kD protein gene of Schistosoma japonicum(Chinese strain). The amino acid sequence shared 98% homology with 21.7 kD protein of Schistosoma japonicum. This fragment was cloned into the expression vector pET28a (+) and subsequently expressed in Escherichia coli with IPTG induction. SDS-PAGE analysis revealed that the molecular weight of this expressed product was 25.4 kD.Western blotting showed that the recombinant protein reacted well with the rabbit serum immunized with Sj worm antigen,indicating that this expressed product had good antigenicity.