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Indeed plasmid DNA is usually what brings up the cost of the transfection step. Less at bench scale, but it quickly becomes expensive at larger scale, and even more so when you need to start producing using GMP grade raw materials. To bring down the amount of plasmid used, the strategy is to primarily rely on a transfection reagent that can allow a significant reduction in plasmid DNA. Typically with PolyPlus transfection reagents, you can reduce the amount of DNA by at least 20% compared to using alternative methods. In a second step, optimization of transfection parameters, DNA/reagent ratio, VCD at transfection and complexation time can further improve productivity and therefore contribute to further decrease overall cost per AAV production batch. To take it a step further, if you have the flexibility in setting up your production system, the HEK-293 cell lineage, the production medium are parameters worth assessing to develop a process that will be scalable to meet your AAV manufacturing needs.