Fully aseptic single-use cross flow filtration system for clarification and concentration of cytomegalovirus-like particles

We report on the implementation of a fully aseptic, single-use ReadyToProcess cross flow filtration system for scalable clarification and concentration of a cytomegalovirus-like particle (CMV reVLP (R)), in preclinical development at Redbiotec AG, using ultrafiltration/diafiltration (UF/DF). Performed under gentle feed and permeate flow conditions, with a transmembrane pressure below 0.8 bar and a flux below 30 L m-2 h-1, this trial resulted in a close to 100% product recovery in an overall process time of 3.5 h. During clarification, cell viability was maintained throughout the concentration step (10x), while decreasing marginally during diafiltration (with three diafiltration volumes). The UF/DF process yielded an approximately 13-fold concentrated material, with high CMV reVLP (virus-like particle) recovery as determined by the amount of CMV envelope surface protein. We conclude that this system, based on hollow fibers, is a suitable solution for scalable processing of CMV reVLPs, instrumental for a cost-effective manufacturing process of a future vaccine product. Kept in a fully contained circuit throughout the process, this presterilized system enabled an endotoxin-free environment by preventing microorganism contamination; moreover, by enabling a fully aseptic process, sterile filtration may possibly be omitted, which can be challenging because of the large size of the CMV reVLPs.