HCV E1基因序列的原核高效表达及表达产物的初步应用

目的 在原核表达系统中对HCV E1基因进行克隆和高效表达,并初步探讨表达产物在抗－HCV筛选中的作用。方法 通过RT－PCR法从HCV RNA阳性的血清标本中扩增出HCV E1片段,并在扩增用的引物中引入克隆所需的酶切位点,克隆产物经Xba I和EcoR I酶切后,在T4DNA连接酶的作用下克降人经同样双酶切的原核表达载体PMS－31b中,并用此连接产物转化大肠埃杀菌POP2136,挑取具有氨苄抗性的菌东扩大培养后提取质粒进行酶切鉴定,鉴定出的阳性菌经42℃诱导后用SDS－PAGE检查其表达状况,并用Western blot鉴定表达产物有特异性,同时用初步纯化的表达产物用ELISA法检测病人血清。结果 经Sma I酶切后PCR产物被切成144bp和356bp的两个片段,在具有氨苄抗性的菌中提取的质粒经Sma I和Xba I酶切后产生了一356bp的片段;42℃诱导后在SDS－PAGE中出现了一条相对分子质量为31000的条带,其表达量约为17％,经Western blot鉴定后在该处出现了阳性信号;ELISA实验显示在抗HCV阳性的血清中的阳性率约为29．8％（26／90）,而在抗HCV阴性的 血清中其阳性率约为3．9％（3／76）。结论 通过RT－PCR方法将HCV E1基因从HCV RNA阳性的血清标本中调出,构建了HCV E1的原核表达载体－PMS－E1,其表达量为17％,表达产物具有良好的特异性,有望应用于抗HCV的检测中。

Prokaryotic expression of Hepatitis C virus envelope 1 gene and application of the expressed product

OBJECTIVE: To express the HCV E1 gene in E. coli cells and to demonstrate its clinical significance in detection of anti-HCV E1 antibodies. METHODS: The expression vector was constructed by ligation of HCV E1 sequence, which was amplified by RT-PCR methods from 50 microliters of HCV RNA positive serum using primers specific to the HCV E1 sequence, to the prokaryotic expression vector PMS-31b transfected POP2136 at 16 degrees C for 16 hours. The recombinant plasmid was screened out and characterized by restriction enzyme analysis. The bacteria containing the recombinant plasmid was induced at 42 degrees C for 4 hours, and the recombinant protein was visualized by SDS-PAGE. The specificity of the recombinant protein was determined by Western blot assay. After purification of the expressed protein, this protein was coated on the plate with the concentration of 2 micrograms/ml in pH 9.6 buffer at 4 degrees C for overnight, and the serum specimen was tested at the dilution of 1:20 by ELISA. RESULTS: There were 2 fragments could be seen on the SDS-PAGE after digestion of the RT-PCR product with Sma I. And there emerged one fragment of 356 bp after digesting the recombinant plasmid with Sma I and Xba I. A band of 30,000 could be seen on the SDS-PAGE after the induction of bacteria containing the recombinant plasmid pMS-E1 at 42 degrees C for 4 hours. The Western blot assay showed that the expressed band could react with the anti-HCV positive serum. The ELISA result indicated that there were 28.9% (26/90) anti-HCV positive serum were anti-HCV E1 positive, but 3.9% (3/76) were positive in the anti-HCV negative serum. CONCLUSION: The HCV E1 sequence from HCV RNA positive serum has been expressed in E. coli. The expression rate is about 17% of the total protein of the bacteria. This protein possessed good specificity and may be used in the diagnosis of HCV infection.