Endotoxin-free γ-PGAs with different average molecular masses (500- and 2,000-kDa), which were prepared as described previously60, were provided by BioLeaders (Daejeon, Korea). The plasmids expressing human TLR4, CD14, and MD2 were described61,62. In transient expression experiments, empty vector was added to normalize the total amounts of transfected DNA. Plasmids were transfected into cells using Fugene HD transfection reagent (Roche Diagnostics, Indianapolis, IN, USA). Chemically synthesized siRNAs were purchased from Bioneer (Daejeon, Korea). The siRNA used are as follows: siTLR4 [siRNA targeting mouse TLR4, 5′-GAAUUGUAUCGCCUUCUUAdTdT-3′ (passenger stand) and 5′-UAAGAAGGCGAUACAAUUCdTdT-3′ (guide strand)] and siCtrl [control siRNA targeting GFP, 5′-CUCGCCGGACACGCUGAACUU-3′ (passenger stand) and 5′-GUUCAGCGUGUCCGGCGAGUU-3′ (guide strand)]. siRNAs were transfected into RAW264.7 cells using the ND98 lipidoid as a transfection reagent63. Mouse polyclonal anti-IRF-3 (FL-425), rabbit monoclonal anti-phospho-IRF-3(Ser396), and rabbit polyclonal anti-β-actin antibody were purchased from Cell Signaling Technology (Beverly, MA, USA). Anti-norovirus capsid protein VP1 antibody was purchased from Abcam (Cambridge, UK). Anti-TLR2 (H-175), anti-TLR3 (N-14), anti-TLR4 (25), and anti-villin antibodies were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA). Anti-α-tubulin antibody was purchased from Calbiochem (La Jolla, CA, USA).