Figure 2

SM reduces IVA replication. (A) Dose response curves of SM for MDCK and A549 cell lines. Cells were incubated with increasing concentrations of SM for 24 h. After incubation, cell viability was measured by MTT assay. The results are expressed as a percentage of viable cells observed after treatment with compounds vs control cells (100%) incubated in the presence of 0.1% DMSO. The data are obtained from at least three independent experiments done in triplicate. Dashed line indicates the nontoxic span of SM concentrations. (B) Effect of SM on IVA reproduction on different epithelial cell lines. MDCK and A549 cells were infected with IVA at MOI 0.01. After 1 h adsorption at standard conditions, the monolayers were washed twice with PBS and incubated at standard conditions in fresh infection medium with SM (1 µM) for 24 h. Viral yields in supernatants were determined by FFA. Control – untreated IVA-infected cells. SM – SM-treated IVA-infected cells. Error bars represent the standard deviation of three independent experiments performed in triplicate. P value: *<0.05. (C) Effects of SM on the expression of IVA nucleoprotein (NP) in A549 cells. Confluent A549 cells were infected with IVA (MOI = 0.1) and then treated with SM (1 µM). At 6 h p.i. the cells were fixed with paraformaldehyde and expression of viral NP protein was detected by IFA (FITC corresponding to NP protein, nuclei were counterstained with DAPI). Cells were viewed using laser scanning confocal microscope with a 10× objective. Bars, 100 µm.