IL6 and viral infectious disease: We hypothesize that at the onset of viral infection in the periphery, the initial upregulation of proinflammatory factors (IL-6, type 1 and 2 IFNs) may have altered the endothelial cells in the blood brain barrier, favoring the entry of proinflammatory cytokines and/or lymphocytes, leading to microglia and neuronal activation, even prior to virus entry (22–24).