CD163 and infection: Even more direct evidence comes from a recent study which clearly demonstrated that around 82% of CD163+ macrophages found later in SIVE lesions were already present in the CNS at day 20 post infection (the time of the first intracisternal injection of dextran dyes to selectively label pre-existing perivascular macrophages), a time point when no significant monocyte infiltration was found, and well before the development of encephalitis5.