猪瘟病毒衣壳蛋白靶向核酸酶表达系统的建立及鉴定

Establishment and Identification of Classical Swine Fever Virus(CSFV) Capsid Targeted Nuclease Expression System

根据猪瘟病毒衣壳蛋白(C)基因序列设计一对引物,RT-PCR扩增获得编码猪瘟病毒衣壳蛋白的C基因,将其插入到含有葡萄球菌核酸酶(SN)基因的真核表达载体pcDNA-SN中,筛选获得重组质粒pcDNA-C-SN。脂质体转染猪肾细胞(PK-15),并经G418稳定筛选,通过RT-PCR、免疫印迹和间接免疫荧光鉴定表达的融合蛋白,体外DNA消化试验检测核酸酶活性。结果表明融合蛋白C-SN在PK-15细胞中获得了稳定表达,能够被兔抗猪瘟病毒衣壳蛋白多抗所识别,并具有良好的核酸酶活性,能够对DNA进行切割。同时,稳定表达融合蛋白C-SN的PK-15细胞系中能够有效抑制猪瘟野毒的增殖,使其感染性降低102～103倍。这些结果为进一步将衣壳蛋白靶向病毒灭活策略应用于抵抗猪瘟病毒感染奠定了基础。

One pair of primers was designed based on the sequence encoding capsid protein C ot classical swine fever virus （CSFV）. The C gene fragment was amplified by RT-PCR and PCR products were inserted into eukaryotic expression vector pcDNA-SN containing staphylococcal nuclease （SN） gene resulting in recombinant plasmid pcDNA-C-SN. 48h after transfection of the recombinant into porcine kidney （PK）-15 cells using liposome, the expression of fusion protein was identified through RT-PCR, Western blot and indirect immunofluorescence, and nuclease activity was detected by in vitro DNA digestion assay. The results showed that fusion protein of C-SN was expressed stably in PK-15 cells, and could be identified by rabbit polyclonal antibody against CSFV capsid protein and had good nuclease activity to cleave DNA. Meanwhile, the expressed fusion protein of C-SN in the transfected cells could effectively inhibit the proliferation of CSFV, reducing the infection rate by 102-103 times. Our findings laid a foundation for further application of capsid-targeted antiviral strategies for CSFV.