Analysis of promoter activity of selected Cotesia plutellae bracovirus genes

Abstract

In a previous study, we cloned 27 discrete genome segments ofCotesia plutellaebracovirus (CpBV) and provided the complete nucleotide sequences and annotation. Seven putative coding regions were predicted from one of the largest segments, CpBV-S30. The activity of promoters associated with six predicted ORFs from this segment were investigated using both transient and baculovirus expression assays with enhanced green fluorescent protein as a reporter gene. CpBV promoters showed activity earlier than thepolyhedrinpromoter and the activity of some of these promoters was superior to that of theAutographa californicamultiple nucleopolyhedrovirus (AcMNPV)ie-1promoter in the baculovirus expression assays. The promoter of ORF3004 showed the highest level of activity in insect cells, exhibiting 24 % of the activity obtained with the AcMNPVpolyhedrinpromoter in Sf9 cells. InSpodoptera exigualarvae, the ORF3006 promoter showed the highest activity, with about 35 % of the activity measured with thepolyhedrinpromoter. In addition, analysis of the ORF3006 promoter revealed that the region between −382 and −422 from the translation start point was critical for activity of this promoter. These results suggest that the CpBV-S30 promoters characterized here could be useful tools in a variety of biotechnological applications, such as gene expression analyses and insecticide development.