Targeted knockdown of ATM, ATR, and PDEδ increases Gag HIV-1 VLP production in HEK293 cells.

Several strategies have been developed in recent years to improve virus-like particle (VLP)-based vaccine production processes. Among these, the metabolic engineering of cell lines has been one of the most promising approaches. Based on previous work and a proteomic analysis of HEK293 cells producing Human Immunodeficiency Virus-1 (HIV-1) Gag VLPs under transient transfection, four proteins susceptible of enhancing VLP production were identified: ataxia telangiectasia mutated (ATM), ataxia telangiectasia and rad3-related (ATR), DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and retinal rod rhodopsin-sensitive cGMP 3',5'-cyclic phosphodiesterase subunit delta (PDEδ). The knockdown of ATM, ATR, and PDEδ in HEK293 cells increased HIV-1 VLP titers in the supernatant by 3.4-, 2.1-, and 2.2-fold, respectively. Also, possible metabolic synergies between plasmids were investigated by statistical design of experiments (DoE), enabling us to identify the optimal production strategy, that was further demonstrated at lab-scale stirred tank bioreactor operated in perfusion, significantly increasing both VLPs specific and volumetric productivities to 8.3 × 103 VLPs/cellxday and 7.5 × 1012 VLPs/Lxday, respectively. KEY POINTS: • ATM, ATR, and PDEδ knockdowns increased VLP production in HEK293 cells. • Knockdown of ATM increased budding efficiency and extracellular vesicle concentration. • ATM knockdown could be intensified to bioreactor scale operated in perfusion.