Membrane-based approach for the downstream processing of influenza virus-like particles

Currently marketed influenza vaccines are only efficient against homologous viruses, thus requiring a seasonal update based on circulating subtypes. This constant reformulation adds several challenges to manufacturing, particularly in purification due to the variation of the physicochemical properties of the vaccine product. A universal platform approach capable of handling such variation is therefore of utmost importance. In this work, a filtration-based approach is explored to purify influenza virus-like particles. Switching from adsorptive separation to size-based purification allows overcoming the differences in retention observed for different influenza strains. The proposed process employs a cascade of ultrafiltration and diafiltration steps, followed by a sterile filtration step. Different process parameters were assessed in terms of product recovery and impurities´ removal. Membrane chemistry, pore size, operation modes, critical flux, transmembrane pressure, and permeate control strategies were evaluated. After membrane selection and parameter optimization, concentration factors and diafiltration volumes were also defined. By optimizing the filtration mode of operation, we were able to achieve product recoveries of approximately 80%. Overall, we decreased process time by 30%, improved its scalability and reduced the costs due to the removal of chromatography and associated buffer consumptions, cleaning and its validation steps.