*2.5. Calculation of EC50*

EGCG was serially diluted to 100, 50, 25, 12.5, 6.25 and 3.125 μM, and was added to PK-15 cells which were infected with PCV2 at MOI = 1.0. EGCG was present during whole PCV2 infection. The infected cells without EGCG treatment was set as mock control. TCID50 was determined at 72 hpi and the values of inhibition were calculated as 1 − TCID50(compound)/TCID50(mock) × 100%. The values of inhibition and EGCG concentration were used to establish a dose response curve and further calculate the EC50 (concentration for 50% of maximal effect).
