Genetic fusion of trimerization motifs to the S protein. A, B Scheme of PEDV S protein fused with the trimeric motif. The CMP coiled-coil was appended at the C terminus of the S protein. C Expression analysis of the S protein fused with the trimeric motif. 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 arrows indicate the PEDV S protein.