Fig. 1

Luteolin inhibits RSV replication in A549 cells and MEFs. a Chemical structure of luteolin. b A549 cells were treated with the indicated concentrations of luteolin for 24, 48, 72, 96 and 120 h. Cell proliferation was measured by CCK-8 assay. c A549 cells were pre-treated with the indicated concentrations of luteolin for 24 h before infected with RSV at MOI = 0.05. After infection for 12, 24, 48, 72 and 96 h, cell culture medium was collected for plaque assay to determine the virus titer. A549 cells, MEFs and HPAEpiC cells were pre-treated with the indicated concentrations of luteolin for 24 h before infected with RSV at MOI = 0.05. At the indicated hours post infection, d virus titer was determined by plaque assay and e RSV-F mRNA expression was determined by RT-qPCR. f A549 cells were pre-treated or treated simultaneously with RSV infection or treated after RSV infection at MOI = 0.05. 48 h post infection, cell culture medium was collected for plaque assay to determine the virus titer. Data shown are means ± SEM. Statistical significance was examined by Students’ t-test. P < 0.05 was considered statistically significant. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001. RSV respiratory syncytial virus,; CCK-8 Cell Counting Kit-8, MOI multiplicity of infection