CD8A and infection: Similar populations of persisting CD8+ TRM cells have been described following virus infection of the brain and submandibular glands (Hawke et al., 1998; Wakim et al., 2010; Hofmann and Pircher, 2011), and intracranial labeling experiments have indicated that clusters of neuronal TRM cells are retained in areas of previous infection for at least several weeks (Wakim et al., 2010).