TNF and viral infectious disease: Examination of other genes known to modulate microglial activity, including the toll-like receptors (tlr1, tlr3, tlr4, tlr6 and tlr9), gfap, il-1b, il-6, ptgs2 and tnf-α did not show any statistically significant alterations in expression levels following CA/09 virus infection at 7, 10 or 21 dpi in the SN (S1 Table).