FIG 2.

In vitro characterization of the N93/95A mutant. (A) Plaques of recombinant PEDVs in Vero cells. The mock-, N93/95A-, or icPC22A-infected cells were fixed and stained with crystal violet at 72 hpi. (B) Multistep growth curves of recombinant PEDVs (N93/95A mutant and the parental icPC22A strain) in Vero and LLC-PK1 cells at an MOI of 0.01. (C and D) LLC-PK1 cells were infected with the recombinant PEDV N93/95A or icPC22A strain at an MOI of 0.01. For panel C, cells were harvested at 24 hpi. The expression levels of sgmRNA-3 and sgmRNA-N (left y axis) and genomic RNA (right y axis) are presented. For panel D, we scratched cells from the plates and collected both cells and supernatant. Then, the samples were frozen and thawed for one cycle and centrifuged, and the supernatants were used for testing and calculation of the genomic RNA/TCID₅₀ ratios. Data from three replicates are shown as mean ± standard deviation (SD).