Fig. 4.

(a) Detection of recombinant PEDV S protein by immunofluorescence. The plasmids containing each of the PEDV S genes were transfected into Vero cell suspensions with DIMRIE-C reagent. After 3 days of incubation, cells were fixed with PBS containing 2% formaldehyde for 12 min (permeabilized) or with PBS containing 2.5% formaldehyde and 0.5% triton-100 for 20 min (non-permeabilized), and S protein was stained with PEDV-immunized pig serum (magnification 200×). (b) Quantitation of S protein expression on the cell surface. PEDV S proteins were expressed on Vero cell cultures and fixed and stained as described in Fig. 4a. After immunostaining, cell images were digitally captured, and the area of S protein expression was calculated with VH-H1A5 analyzer (KEYENCE, Osaka, Japan) and normalized with the data from empty vector-transfected control. The amount of S protein expression on the cell surface was represented as the relative value (%) (value of non-permeabilized condition/value of permeabilized condition) (n = 5).