High-level gene expression in Aedes albopictus cells using a baculovirus Hr3 enhancer and IE1 transactivator

BACKGROUND: Aedes aegypti is the key vector of both the Yellow Fever and Dengue Fever viruses throughout many parts of the world. Low and variable transgene expression levels due to position effect and position effect variegation are problematic to efforts to create transgenic laboratory strains refractory to these viruses. Transformation efficiencies are also less than optimal, likely due to failure to detect expression from all integrated transgenes and potentially due to limited expression of the transposase required for transgene integration. RESULTS: Expression plasmids utilizing three heterologous promoters and three heterologous enhancers, in all possible combinations, were tested. The Hr3/IE1 enhancer-transactivator in combination with each of the constitutive heterologous promoters tested increased reporter gene expression significantly in transiently transfected Aedes albopictus C7-10 cells. CONCLUSIONS: The addition of the Hr3 enhancer to expression cassettes and concomitant expression of the IE1 transactivator gene product is a potential method for increasing the level of transgene expression in insect systems. This mechanism could also potentially be used to increase the level of transiently-expressed transposase in order to increase the number of integration events in transposon-mediated transformation experiments.