Fig. 1

TRQ exerts anti-DENV effects in vitro and in vivo. A The cytotoxicity of TRQ on BHK-21 cells. BHK-21 cells were incubated with TRQ for 96 h and cell viability was determined by MTT assay. B TRQ shows no prophylactic anti-DENV activities, as detected by CCK-8 assay. Cells were incubated with different concentrations of TRQ and then infected with DENV-2 for 1 h. C TRQ exerts anti-DENV attachment/entry effects on BHK-21 cells, as detected by CCK-8 assay. BHK-21 cells were infected with 0.5 MOI of DENV-2 with or without TRQ treatment. D TRQ shows no anti-DENV activities after entry into BHK-21 cells, as detected by CCK-8 assay. After infection with 0.5 MOI of DENV-2 for 1 h, BHK-21 cells were treated with TRQ. E TRQ inhibits the production of progeny viruses in DENV-2 infected BHK-21 cells as examined by plaque assay. F Statistical analysis of plaque assay to verify the inhibitory effects of TRQ on DENV- induced progeny virus. G, H TRQ inhibits the viral load in the brain in DENV-2 infected ICR suckling mice at 6 D.P.I., as determined by qRT‒PCR (n = 6). I–K TRQ downregulates the protein expression level of E protein in DENV-2 infected mouse brains, as examined by immunohistochemistry (100 ×) I, J and Western blotting K. The concentrations of TRQ-L, TRQ-M and TRQ-H were 1.25, 2.5 and 5 mL/kg, respectively. Dex was used as a positive drug. ^***P < 0.001 vs. control group. ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. DENV-2 group