Investigation of the generation and functional maturation of regulatory T cells in vivo

This important study will explore T-cell immunity to COVID-19. T-cell immunity is considered to play key roles in the eradication of infection by promoting B-cell maturation and eliciting cytotoxic activities to the virus. It is also known that severe COVID-19 patients show remarkable T-cell dysregulation. However, it is unknown known how T-cells respond to each of the key COVID-19 viral antigens, and there is still an urgent need for basic research on the antiviral T-cell immunity using animal models. Accordingly, I propose to investigate T-cell responses to the key COVID viral antigens (including Spike protein) using our mouse models. Specifically we will test if each of the viral proteins induces a particular type of T-cell responses (e.g. Th1 response, Treg induction). We will analyse not only regulatory T-cell (Treg) responses but also helper T-cell responses and CD8+ T-cell responses to the antigen. We will produce recombinant proteins and perform DNA vaccination to analyse T-cell responses. Nr4a3-Tocky and Foxp3-Tocky, which allow the analysis of antigen-reactive T-cells and Treg dynamics, respectively. The level of urgency and importance The proposed project will produce basic materials and knowledge for (1) improving vaccine strategies by enhancing T-cell immunity; (2) improving the COVID-19 immunity test. The fund by converting the two original activities into the COVID-19 research will be equivalent to a 6-month project. We will apply for a follow-on fund through the UKRI and/or industrial grants, in order to further investigate anti-COVID-19 T-cell immunity and develop new methods for fighting COVID-19. The necessary critical mass: The proposed project will be still within the scope of the original plans, i.e. to investigate the mechanism of the generation and functional maturation of Treg in vivo. Instead of using other antigen models, we will use the viral antigens. Thus, we have all the resources including the key transgenic mouse tools (Foxp3-Tocky and Nr4a3-Tocky mice) for the investigation. We will use a commercial maintenance service and their technical supports for maintaining and obtaining the Tocky mice for experiments, in order to smoothly conduct the planned experiments. Strengths: The proposed project will provide key preliminary data for further developing new methods to improve COVID-19 vaccines and immunity tests.