Baculovirus expression systems (BESs) have been used to express many foreign proteins. BESs are known to be very suitable for foreign protein production due to the strong gene expression ability of the polyhedrin promoter. However, expression of foreign proteins using the polyhedrin promoter begins at a very late phase, in the last stage of viral infection. This causes insufficient production of foreign proteins due to death of the host cells. Therefore, our study aimed to construct a vector that can enable not only earlier production of foreign recombinant proteins but also increased production. For this purpose, a novel overexpression vector based on the polyhedrin promoter was constructed by using transcriptional enhancers (hr3 and repeated burst sequences (BSs)) and an additional promoter capable of inducing earlier gene expression than the polyhedrin promoter. Among the vectors with additional promoters that were evaluated, the overexpression vector with the p6.9 promoter showed the highest foreign protein expression efficiency. This vector showed approximately 94 times greater and one-day-earlier expression of the foreign protein than the control vector containing only the polyhedrin promoter. In order of greatest to least influence, the factors that increased the expression efficiency of the polyhedrin promoter were the repeated BSs, the p6.9 promoter and hr3.

杆状病毒表达系统（BES）已用于表达许多外源蛋白。由于多角体蛋白启动子的强大的基因表达能力，已知BES非常适合于外源蛋白的生产。但是，使用多角体蛋白启动子表达外源蛋白是在病毒感染的最后阶段，即非常晚的阶段开始的。由于宿主细胞的死亡，这导致外源蛋白质的生产不足。因此，我们的研究旨在构建一种载体，该载体不仅能够使外源重组蛋白更早地产生，而且能够增加产量。以此目的，通过使用转录增强子（hr3和重复突发序列（BSs））和一个能够诱导比多角体蛋白启动子更早的基因表达的启动子，构建了一种基于多角体蛋白启动子的新型过表达载体。在带有附加启动子的载体中，带有p6.9启动子的过表达载体表现出最高的外源蛋白表达效率。与仅含有多面体蛋白启动子的对照载体相比，该载体显示外源蛋白的表达高约94倍，并且提前一天表达。按照从最大到最小的影响顺序，增加多角体蛋白启动子表达效率的因素是重复的BS，p6.9启动子和hr3。带有p6.9启动子的过表达载体表现出最高的外源蛋白表达效率。与仅含有多面体蛋白启动子的对照载体相比，该载体显示外源蛋白的表达高约94倍，并且提前一天表达。按照从最大到最小的影响顺序，增加多角体蛋白启动子表达效率的因素是重复的BS，p6.9启动子和hr3。带有p6.9启动子的过表达载体表现出最高的外源蛋白表达效率。与仅含有多面体蛋白启动子的对照载体相比，该载体显示外源蛋白的表达高约94倍，并且提前一天表达。按照从最大到最小的影响顺序，增加多角体蛋白启动子表达效率的因素是重复的BS，p6.9启动子和hr3。