PEDV strain 85-7 (P5) proliferated on Vero cells in a trypsin independent manner. (A) Virus proliferation curve in the presence of 10 ng/μL trypsin at an MOI of 0.1. Plaque titrations from the indicated time points were carried out. Error bars indicate the standard deviation of the mean of three independent experiments. (B) The strain 85-7 could proliferate on Vero cells trypsin-independently. Vero cells were infected at an MOI of 0.1 in the indicated trypsin concentrations (0, 2.5, 10, 20, 30 ng/μL) and the viral titers at 48 hpi were measured and compared.