TNF and infection: The only significant activated CD8+ T response was at day 16 post-OC43 infection, and was focused on a single region in the N protein, with 9- and 12-fold expansion of N104-121-reactive IFNγ+ and IFNγ/TNF+ CD8+ T cells, respectively (Fig. 3B, with the gating strategy represented in Fig. S2C).