FIG 2.

The region of S^att from aa 530 to 590 contains a critical residue(s) determining the Vero cell adaptation of PEDV DR13^att. (A) Schematic representation of the chimeric S proteins of the recombinant viruses r-S^att(1–529 aa)^par, r-S^att(530–936 aa)^par, r-S^att(937–1383 aa)^par, and r-S^par(530–936 aa)^att. (B) Luciferase expression by r-S^att(1–529 aa)^par, r-S^att(530–936 aa)^par, r-S^att(937–1383 aa)^par, and r-S^par(530–936 aa)^att. The intracellular Renilla luciferase activities of the first two generations (P0 and P1) of recombinant viruses were determined (y axis) (relative light units [RLU]). The results are expressed as the mean values from three parallel tests, and error bars represent the SD. Comparisons were made between the luciferase activities of the recombinant viruses and those of the mock treatments. *, P < 0.05; **, P < 0.01. (C) RT-PCR confirmation of the rescued recombinant PEDVs. RT-PCR was performed covering the region of the S protein from aa 530 to 936 (Primers Ped136 [5′-TGCATCTCGGTTTGTTGGATGC-3′] and Ped137 [5′-TATATTACCAATAGCAGAGTTA-3′]) using the RNA template isolated from the recombinant PEDVs, and the protein was analyzed by gel electrophoresis. The expected size of the RT-PCR product was 1,789 bp.