CD8A and viral infectious disease: The recognition of lymphatic structures in the CNS therefore provides two mechanisms by which CD8+ T cells can interact with cognate antigens during viral infection: (1) the recognition of antigen in the periphery, followed by recruitment into the CNS after the pathogen has replicated in the CNS tissue, and (2) the recognition of antigen from the CNS via lymphatic drainage (Figure 3, reviewed in [108]).