Proceedings of the 2019 Viral Clearance Symposium, Session 1: Viral Clearance Strategies and Case Studies

Session 1 of the 2019 Viral Clearance Symposium proposed strategies to use prior knowledge for demonstrating robust viral clearance for biotechnologically produced recombinant proteins, such as monoclonal antibodies, and introduced methods for virus reduction applicable to recombinant adeno-associated virus (rAAV) vectors. Proposals for generic virus clearance claims were made for detergent inactivation with Triton CG-110, low pH inactivation, anion-exchange membrane chromatography, and virus filtration, and acceptance of these proposals were discussed. Furthermore, the development of an ASTM standard for retrovirus removal by small virus filters was presented, and it was found that updating and refining of conditions is still warranted. The current approach for log reduction value calculation by using the lower value from duplicate runs as worst case was questioned, and a modified concept was proposed. Finally, for rAAV vectors, several options for reduction of adventitious viruses were demonstrated such as 35 nm virus filtration, detergent inactivation, heat inactivation, and anion-exchange or affinity chromatography and were found to be feasible in order to satisfy the principles of ICH Q5A.