CsA inhibits EGFP-tagged HP-PRRSV replication. A. CsA at various concentrations inhibited rHP-PRRSV/SD16/TRS6-EGFP infection of Marc-145 cells as shown by the relative EGFP fluorescence expression normalised to the EGFP signal in solvent-treated control cells (100%). B. The effect of CsA at various concentrations on cell viability compared to the viability of untreated control cells (100%) was determined using a CellTiter 96 A Queous nonradioactive cell proliferation assay at 36 h after treatment with CsA. C. CsA at various concentrations inhibited rHP-PRRSV/SD16/TRS6-EGFP and wt HP-PRRSV/SD16 infection of Marc-145 cells by determining the virus titers in the supernatants at 24 h pi. D. CsA at various concentrations inhibited the levels of rHP-PRRSV/SD16/TRS6-EGFP structural proteins N and M and EGFP protein by Western blot analysis.