Codon Optimization, Expression in <i>Escherichia coli</i>, and Immunogenicity of Recombinant Chinese Sacbrood Virus (CSBV) Structural Proteins VP1, VP2, and VP3

Chinese sacbrood virus (CSBV) is a small RNA virus family belonging to the genus Iflavirus that causes larval death, and even the collapse of entire bee colonies. The virus particle is spherical, non-enveloped, and its viral capsid is composed of four proteins, although the functions of the structural proteins are unclear. In this study, we used codon recoding to express the recombinant proteins VP1, VP2, and VP3 in Escherichia coli. SDS-PAGE analysis and Western blotting revealed that the target genes were expressed at high levels. Mice were then immunized with the purified, recombinant proteins, and antibody levels and lymphocyte proliferation were analyzed by ELISA and the MTT assay, respectively. The results show that the recombinant proteins induced high antibody levels and promoted lymphocyte proliferation. Polyclonal antibodies directed against these proteins will aid future studies of the molecular pathogenesis of CSBV.中国囊状幼虫病病毒（Chinese sacbrood virus, CSBV）是一类隶属于伊夫拉病毒属（Iflavirus）的小型RNA病毒，可引发幼虫死亡，甚至造成整个蜂群崩溃。该病毒粒子呈球形、无包膜，病毒衣壳由四种蛋白质构成，但其结构蛋白的功能目前尚不明确。本研究采用密码子重编码技术，在大肠杆菌（Escherichia coli）中重组表达VP1、VP2及VP3蛋白。经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析与蛋白质免疫印迹（Western blotting）检测，结果显示靶基因实现了高效表达。随后，利用纯化后的重组蛋白免疫小鼠，分别通过酶联免疫吸附测定（ELISA）与MTT比色法（MTT assay）检测抗体水平及淋巴细胞增殖情况。实验结果表明，重组蛋白可诱导产生高滴度抗体，并能促进淋巴细胞增殖。针对上述蛋白制备的多克隆抗体，将为后续开展CSBV分子致病机制的相关研究提供有力支持。