Figure 6. TLR3 is dispensable in mediating the anti-viral responses of PIKA in mice.

(A) Human embryonic kidney (HEK 293 cells) were transfected with an NF-κB-luciferase reporter gene and a β-galactosidase-expressing plasmid with or without co-transfection of the indicated TLR3, MDA-5 or RIG-I receptor-expressing plasmids. Twenty–four hours after transfection, the cells were stimulated with 50 ng of PIKA in plain medium for 6 hours before the cells were lysed and luciferase activity in the lysates was determined. The data were normalized to β-galactosidase activity and expressed as fold-increase relative to expression in cells that were transfected with respective receptor-expressing plasmids without PIKA stimulation. The bar and error bars represent the mean and standard error of 8 replicates and are representative of two independent experiments. (B) Groups of three TLR3^−/− or TLR3^+/+ mice received PIKA or PBS intranasally and were sacrificed 24 hours later. Lung homogenates were prepared and the concentration of various cytokines was determined as previously described. Data are expressed as the fold-increase in PIKA-treated mice over PBS-treated mice. Groups of five TLR3^−/− or TLR3^+/+ mice received PIKA and were challenged with the H7N1 virus as previously described. Virus titers in the NT (C) and lungs (D) were determined in MDCK cells. The horizontal bars represent the geometric mean of the group. The `*' symbol indicates that the difference between the groups was statistically significant (p<0.05).