1. Single-shot dendritic cell targeting SARS-CoV-2 vaccine candidate induces broad, durable and protective systemic and mucosal immunity in mice
- Author
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Cheang, NYZ, Tan, KS, Tan, PS, Purushotorma, K, Yap, WC, Tullett, KM, Chua, BYL, Yeoh, AY-Y, Tan, CQH, Qian, X, Chen, H, Tay, DJW, Caminschi, I, Tan, YJ, Macary, PA, Tan, CW, Lahoud, MH, Alonso, S, Cheang, NYZ, Tan, KS, Tan, PS, Purushotorma, K, Yap, WC, Tullett, KM, Chua, BYL, Yeoh, AY-Y, Tan, CQH, Qian, X, Chen, H, Tay, DJW, Caminschi, I, Tan, YJ, Macary, PA, Tan, CW, Lahoud, MH, and Alonso, S
- Abstract
Current coronavirus disease 2019 vaccines face limitations including waning immunity, immune escape by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, limited cellular response, and poor mucosal immunity. We engineered a Clec9A-receptor binding domain (RBD) antibody construct that delivers the SARS-CoV-2 RBD to conventional type 1 dendritic cells. Compared with non-targeting approaches, single dose immunization in mice with Clec9A-RBD induced far higher RBD-specific antibody titers that were sustained for up to 21 months after vaccination. Uniquely, increasing neutralizing and antibody-dependent cytotoxicity activities across the sarbecovirus family was observed, suggesting antibody affinity maturation over time. Consistently and remarkably, RBD-specific follicular T helper cells and germinal center B cells persisted up to 12 months after immunization. Furthermore, Clec9A-RBD immunization induced a durable mono- and poly-functional T-helper 1-biased cellular response that was strongly cross-reactive against SARS-CoV-2 variants of concern, including Omicron subvariants, and with a robust CD8+ T cell signature. Uniquely, Clec9A-RBD single-shot systemic immunization effectively primed RBD-specific cellular and humoral immunity in lung and resulted in significant protection against homologous SARS-CoV-2 challenge as evidenced by limited body weight loss and approximately 2 log10 decrease in lung viral loads compared with non-immunized controls. Therefore, Clec9A-RBD immunization has the potential to trigger robust and sustained, systemic and mucosal protective immunity against rapidly evolving SARS-CoV2 variants.
- Published
- 2024