Improved RSV preF protein vaccine quality and stability by elucidation of supercooling-induced aggregation phenomena

[Display omitted] Through a synergistic collaboration of people with varying backgrounds and expertise, the root-cause of respiratory syncytial virus prefusion (preF) protein aggregation during freezing was identified to be supercooling. This issue was addressed through a comprehensive understanding of the product. Leveraging innovative and unconventional methods, apparatus, and approaches, it was effectively determined that key parameters influencing aggregation were the nucleation temperature and the duration of supercooling. Moreover, additional measurements revealed that a transition from the preF to the postfusion conformation occurs upon supercooling, which is likely caused by cold denaturation. The importance of considering freezing conditions is highlighted supporting analytical sampling and envisioning that better understanding of sample handling/freezing process can be applied to a wide range of protein-based products.