To determine whether memory CD8+ T cells that traffic directly into VacV-infected skin also relied on local antigen recognition to become a CD69+ TRM, we co-infected LCMV-immune mice with VacV-GP33 on the left ear skin and VacV expressing the model antigen OVA257-264 (VacV-OVA) on the right, as these viral infections are restricted to the skin microenvironment and do not become systemic [18]. Here, CD69 is linked to viral infectious disease.