The present study was aimed at comparing different E. coli strains in expressing the capsid protein of Porcine Circovirus 2 (PCV2). Full length capsid protein could be expressed only in Rosetta-gami 2 (DE3) pLysS strain using pET32b (+) vector. This confirmed that only those strains which possess tRNAs for rare codons can express the full length capsid protein. Purification of full length capsid protein could not be achieved even after several attempts using native and denaturing conditions. Subsequently, an attempt was made for expression of N-terminal truncated capsid protein using the same expression system. Truncated capsid protein was successfully expressed, purified and characterized by western blotting. The truncated capsid protein was also shown to be efficacious in testing serum samples using an optimized indirect ELISA, wherein a diagnostic sensitivity of 88.89% and specificity of 90.82% was obtained as compared to commercially available GreenSpring® porcine circovirus (PCV2) ELISA test kit. Thus, the expressed truncated capsid protein appears to be a promising diagnostic agent for PCV2. The comparative analysis suggests that cluster of arginine residues at N-terminal of capsid protein not only affects its expression in some E. coli strains but also its purification by Ni-NTA chromatography, when expressed as a histidine tagged fusion protein.

中文翻译：

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比较不同大肠杆菌菌株生产猪圆环病毒2型重组衣壳蛋白的效率。

本研究旨在比较不同的大肠杆菌菌株在表达猪圆环病毒2（PCV2）的衣壳蛋白中的作用。使用pET32b（+）载体只能在Rosetta-gami 2（DE3）pLysS菌株中表达全长衣壳蛋白。这证实了只有那些拥有稀有密码子的tRNA的菌株才能表达全长衣壳蛋白。即使使用天然和变性条件进行了几次尝试，也无法实现全长衣壳蛋白的纯化。随后，尝试使用相同的表达系统表达N末端截短的衣壳蛋白。截短的衣壳蛋白已成功表达，纯化并通过蛋白质印迹进行了表征。还显示了截短的衣壳蛋白在使用优化的间接ELISA检测血清样品中是有效的，其中，与市售的猪圆环病毒（PCV2）ELISA检测试剂盒相比，诊断灵敏度为88.89％，特异性为90.82％。因此，表达的截短的衣壳蛋白似乎是有希望的PCV2诊断剂。对比分析表明，衣壳蛋白N末端的精氨酸残基簇不仅影响其在某些大肠杆菌菌株中的表达，而且还以Ni-NTA色谱法纯化（以组氨酸标记的融合蛋白表达）。