TLR4 and Japanese encephalitis: In addition, since two genetic backgrounds of mouse strains used for TLR3−/− and TLR4−/− mice could complicate the comparison of susceptibility to JE, we directly compared the susceptibility to JE between TLR3−/− mice and wild-type mice, using TLR3−/− mice derived from the same genetic background (H-2b) as TLR4−/− mice.