Downstream processing for influenza vaccines and candidates: An update.

Seasonal and pandemic influenza outbreaks present severe health and economic burdens. To overcome limitations on influenza vaccines' availability and effectiveness, researchers chase universal vaccines providing broad, long-lasting protection against multiple influenza subtypes, and including pandemic ones. Novel influenza vaccine designs are under development, in clinical trials, or reaching the market, namely inactivated, or live-attenuated virus, virus-like particles, or recombinant antigens, searching for improved effectiveness; all these bring downstream processing (DSP) new challenges. Having to deal with new influenza strains, including pandemics, requires shorter development time, driving the development of faster bioprocesses. To cope with better upstream processes, new regulatory demands for quality and safety, and cost reduction requirements, new unit operations and integrated processes are increasing DSP efficiency for novel vaccine formats. This review covers recent advances in DSP strategies of different influenza vaccine formats. Focus is given to the improvements on relevant state-of-the-art unit operations, from harvest and clarification to purification steps, ending with sterile filtration and formulation. The development of more efficient unit operations to cope with biophysical properties of the new candidates is discussed: emphasis is given to the design of new stationary phases, 3D printing approaches, and continuous processing tools, such as continuous chromatography. The impact of the production platforms and vaccine designs on the downstream operations for the different influenza vaccine formats approved for this season are highlighted.

Purification of influenza virus-like particles using sulfated cellulose membrane adsorbers.

BACKGROUND: Vaccines based on virus-like particles (VLPs) are an alternative to inactivated viral vaccines that combine good safety profiles with strong immunogenicity. In order to be economically competitive, efficient manufacturing is required, in particular downstream processing, which often accounts for major production costs. This study describes the optimization and establishment of a chromatography capturing technique using sulfated cellulose membrane adsorbers (SCMA) for purification of influenza VLPs. RESULTS: Using a design of experiments approach, the critical factors for SCMA performance were described and optimized. For optimal conditions (membrane ligand density: 15.4 µmol cm-2, salt concentration of the loading buffer: 24 mmol L-1 NaCl, and elution buffer: 920 mmol L-1 NaCl, as well as the corresponding flow rates: 0.24 and 1.4 mL min-1), a yield of 80% in the product fraction was obtained. No loss of VLPs was detected in the flowthrough fraction. Removal of total protein and DNA impurities were higher than 89% and 80%, respectively. CONCLUSION: Use of SCMA represents a significant improvement compared with conventional ion exchanger membrane adsorbers. As the method proposed is easily scalable and reduces the number of steps required compared with conventional purification methods, SCMA could qualify as a generic platform for purification of VLP-based influenza vaccines. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.