Title : 3D- Vaxlock Technology stabilizes the prefusion conformation of the RSV F protein resulting in a highly potent and stable subunit vaccine candidate
Abstract:
Viral fusion proteins enable cellular infection by fusing viral and cellular membranes accompanied by their transition from the pre-fusion to the post-fusion conformation during viral entry. Fusion proteins in their prefusion conformation elicit high neutralizing antibodies, but they are metastable and readily transition to postfusion irreversibly when used as subunit vaccines. Therefore, conformational stabilization is required to maintain the more potent prefusion state. In order to achieve this, we have developed a proprietary engineering technology, 3D-Vaxlock, that introduces Dityrosine (DT) crosslinks between Tyr residues in proximal side chains in the protein structure to stabilize protein conformations. Dityrosine crosslinks form naturally in proteins like elastin, collagen, and resilin where they provide structural rigidity and high stability. We have leveraged these specificities to stabilize the spring-loaded prefusion conformation of the RSV F protein in order to elicit the most potent neutralizing antibodies (nAbs), resulting in a better subunit vaccine immunogen. We engineered tyrosine crosslinks in the soluble RSV F glycoprotein trimer by structure-based design that lock the prefusion conformation by stabilizing two potent antigenic sites (Site and the IV/V interface). These crosslinks preserve epitopes recognized by potent prefusion-specific mAbs resulting in improvements to stability and potency. Dityrosine crosslinked prefusion F protein (DT-preF) maintained the prefusion conformation for 5 weeks at 4 ºC and improved shelf life in an immunogenicity experiment compared to DS-Cav1 (a traditionally stabilized prefusion F protein). DT-preF also demonstrated 9-fold higher nAbs as compared to DS-Cav1 in a mouse immunogenicity study, complete protection in cotton rats, and overcame immunosenescence in aged mice with a high dose formulation on alum.
