Primary murine microglia constitutively express members of the RLR family of cytosolic pattern recognition receptors and such expression is elevated following viral challenge. Cells (2 × 106) were untreated (0) or exposed to VSV (ratios of viral particles to cells: 0.001:1, 0.01:1, 0.1:1, 1:1, and 10:1). (A) At 4 h following infection, mRNA was isolated and real-time PCR performed to determine the level of expression of mRNA encoding RIG-I or MDA5. Data are presented as the mean ± SEM of four experiments normalized to the expression of G3PDH. Asterisk indicates a statistically significant difference from uninfected microglia. (B) At 24 h post infection, whole-cell protein isolates were prepared and RIG-I and MDA5 protein expression were determined by immunoblot analyses. Immunoblots shown are representative of four separate experiments. For comparison purposes RLR protein expression in spleen tissue protein isolates is shown (SPL).