New reagents for quantifying the routing and kinetics of t-cell activation
The activation of The activation of cytotoxic T-cells (CTLs) marks the key step in the adaptive immune response against cancer and viral infections. Vaccines that activate the CTL-response against tumours are currently hotly pursued, with those targeting tumour-specific mutations now reaching the clinic. However, the capacity of these vaccines to actually activate CTLs is low and rational design improvements are needed to broaden their application. For this, better in vivo knowledge on the processes leading to CTL-activation is needed. 

CTLs are activated by dendritic cells. These cells take up the vaccine, and process it to 8-10-mer peptides for presentation to CTLs on MHC-I complexes. A process called cross-presentation. In this proposal, I aim to quantify key unknowns of this pathway, relating to its kinetics and the subcellular route a vaccine takes to reach the MHC-loading site. I will:  

a)  Quantify the kinetics of peptide-MHC appearance, persistence and disappearance, in vivo using vaccines carrying bioorthogonal protecting/blocking groups that allow me to chemically activate, and stop, the recognition by CTLs in time. 
b) I will also study the sub-cellular route(s) the vaccine antigens take in vivo, by developing a second family deprotection and blocking reagents that are targeted to specific organelles. 

This localised vaccine activation (or de-activation) will allow me to study the different proposed subcellular routes of the antigen in isolation and assess the importance of the many proposed subcellular routes in vivo to overall cross-presentation success. 

The kinetic and routing information obtained from this new set of reagents, will allow me to shed light on some of the key unknowns relating to cross-presentation in vivo, and assess their importance to the success of CTL-activation. By using vaccine-models closely related to existing cancer vaccines, these data will in turn serve to support the rational design of better anti-tumour vaccines.