OT-I CD8+ T cells were recruited equally to both the control (N4-infected) and experimental (APL-infected) skin on day 7 post infection, but the frequency of OT-I CD8+ T cells expressing IFNγ directly correlated with the strength of TCR signal received within the VacV-infected skin microenvironment (Fig. 2e–g). This evidence concerns the gene IFNG and infection.