RESUMO
To study the effect and underlying mechanism of Mahuang Tang against influenza A virus in vitroï¼ the influenza virus-infected Madin-Darby canine kidney(MDCK) cells were used as the carrier in this study to detect the median tissue culture-infective dose(TCID50) of influenza A virus strains(A/PR8/34) on MDCK cells with cytopathic effect(CPE) assay. Blocking influenza virus invading host cells and anti-influenza virus biosynthesis were used as two different administration methodsï¼ and then the methyl thiazolyl tetrazolium(MTT) assay was utilized to determine the antiviral effective rate(ER)ï¼ median efficacious concentration(EC50) and therapeutic index(TI) of Mahuang Tang. The quantitative Real-time polymerase chain reaction(RT-PCR) was used to measure virus load and the mRNA expression levels of TLR4ï¼ TLR7ï¼ MyD88 and TRAF6 in MDCK cells at 24ï¼ 48 h after the treatment. The experiment results indicated that TCID50 of A/PR8/34 for MDCK cells was 1×10-4.32/mL. The EC50 values of two different treatment methods were 4.92ï¼1.59 g·L⻹ respectivelyï¼ the TI values were 12.53ï¼ 38.78 respectivelyï¼ and when the concentration of Mahuang Tang was 5.00 g·Lâ»¹ï¼ ER values were 50.21%ï¼ 98.41% respectivelyï¼ showing that Mahuang Tang can block influenza virus into the host cells and significantly inhibit their biosynthesis. Meanwhileï¼ as compared with the virus groupï¼ the virus load was significantly inhibited in Mahuang Tang groupsï¼ and Mahuang Tang high and middle doses had the significant effect on decreasing the mRNA expression of TLR4ï¼ TLR7ï¼MyD88 and TRAF6 at 24ï¼ 48 h after the treatment. It can be demonstrated that the mechanisms of Mahuang Tang against influenza A virus are related to the inhibition of influenza virus replication and the mRNA expression of correlative genes in TLR4 and TLR7 signaling pathways.