without antiviral) to 45% and 100% in presence of Acyclovir (10ml/ mL and 100 mg/mL, respectively). These results are correlated with the decreased of viral load measured in the presence of Acyclovir: 1010 genome copies/mLwith EHV-1 only,106 copies/mL with EHV-1 + Acyclovir 10 mg/mL and 105 copies/mLwith EHV-1 + Acyclovir 100 mg/ mL. In conclusion, the cellular impedance monitoring system is a new real-time method to monitor cell growth and viral proliferation in cell cultures. This technology is well adapted for high-throughput screening of antiviral molecules. In fact, the xCELLigence system enables continuous impedance measurement and quantification of cell adhesion, proliferation, cell death and detachment during viral infection.