Expression of the ectodomain of PEDV S protein in cultured silkworm cells and silkworm larva. A Transmembrane (TM) domain prediction of PEDV S protein. The TM domains predicted using TMHMM v.2.0 software and SOSUI software are indicated by a blue and red underline, respectively. B The constructions of baculovirus transfer vector. pPH: polyhedrin promoter; B1 and B2: recombination sites for Gateway cloning; L21: translational enhancer; Tags: TEV protease cleavage site, 8 × histidine tag, STREP(II) tag, 6 × histidine tag, and Ktag (MKHKGS); SV40pA: polyadenylation signal (SV40). C Expression of PEDV S(1–1320) and S(1–1332) protein in BmO2 cells (left panel) and silkworm larva (right panel). Medium: culture medium; Soluble: soluble samples of cell lysates; Insoluble: insoluble samples of cell lysates. All samples from BmO2 cells (5 μL) and silkworm sera (0.5 μL) were resolved on an 8% SDS-PAGE. The recombinant PEDV S protein was also detected by Western blotting using HisProbe-HRP. Orange and blue arrows indicate the PEDV S protein and the cleaved products, respectively.