Objective: To investigate the regulation effect of Isatidis Radix-containing serum on interferon-β(IFN-β)

Toll-like receptors 3(TLR3)

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interferon regulatory factor 3(IRF3) in RAW264.7 cells infected with virus

in order to explore its antiviral mechanism and provide experimental basis for clinical application. Method: The experiment was divided into 6 groups:normal control group

RSV infected model group

Isatidis Radix low

medium and high dose groups (40%

50%

60% Isatidis Radix-containing serum)

and Ribavirin group (70% Ribavirin-containing serum). RAW264.7 cells were infected with RSV

and treated with Isatidis Radix-containing serum or Ribavirin-containing serum. After 12 hours

supernatant was collected to detect the level of IFN-β with ELISA assay

cells were collected to detect the level of TLR3

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IRF3 and IFN-β mRNA with Real-time PCR

and protein expressions of TLR3

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IRF3 and p-IRF3 were detected by Western blot. Result: Compared with normal group

model group showed obvious increases in expressions of TLR3

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IFN-β mRNA and protein of TLR3

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p-IRF3 12 h later after RAW264.7 cells were infected with RSV (P<0.01)

with no significant change in IRF3 mRNA and protein. Compared with model group

medium and high-dose Isatidis Radix groups showed obvious decreases in the high expressions of TLR3

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IFN-β mRNA (P < 0.05

P < 0.01) and the high expressions of protein of TLR3

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p-IRF3 (P<0.05). The down-regulation effect of Isatidis Radix-containing serum was lower than that of Ribavirin-containing serum. Both of Isatidis Radix-containing serum and Ribavirin-containing serum had no a significant effect on the expressions of protein of IRF3 and mRNA of IRF3. Conclusion: RSV can activate TLR3 signaling transduction pathway to promote the expression of IFN-β. Isatidis Radix-containing serum can down-regulate TLR3

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p-IRF3 of TLR3 signaling transduction pathway to control the proper expression of IFN-β.