An efficient and scalable process for helper-dependent adenoviral vector production using polyethylenimine-adenofection

Safety requirements for adenoviral gene therapy protocols have led to the development of the third generation of vectors commonly called helper-dependent adenoviral vectors (HDVs). HDVs have demonstrated a high therapeutic potential; however, the poor efficiency and reliability of the actual production process hampers further large-scale clinical evaluation of this new vector. The current HDV production methods involve a preliminary rescue step through transfection of adherent cell cultures by an HDV plasmid followed by a helper adenovirus (HV) infection. Amplification by serial co-infection of complementary cells allows an increase in the HDV titer. Using a HEK293 FLP/frt cell system in suspension culture, an alternative protocol to the current transfection/infection procedure was evaluated. In this work, the adenofection uses the HDV plasmid linked to the HV with the help of polyethylenimine (PEI) and has shown to outperform standard protocols by producing higher HDV yield. The influence of complex composition on the HDV production was examined by a statistical design. The optimized adenofection and amplification conditions were successively performed to generate HDV at the 3 L bioreactor scale. Following only two serial co-infection passages, up to 1.44 x 10(8) HDV infectious units/mL of culture were generated, which corresponded to 26% of the total particles produced. This production strategy, realized in cell suspension culture, reduced process duration and therefore the probability of vector recombination by introducing a cost-effective transfection protocol, ensuring production of high-quality vector stock.