Schematic of the full-length porcine deltacoronavirus (PDCoV) genome and construction of the infectious PDCoV cDNA clone. (A) The upper panel is the PDCoV genome, including ORF1a, ORF1b, and the spike (S), envelope (E), membrane (M), ORF6, ORF7, and nucleocapsid (N) genes. The lower panel is cDNA fragments comprising icPDCoV. Restriction sites joining fragments are shown. (B) Lanes a, b, c, d, and e correspond to the agarose electrophoresis of the digested plasmids containing fragments A, B, C, D, and E. (C) Diagram of engineered S protein in chimeric viruses. (D) 3D model of the structure of S proteins homo-trimer from recombinant viruses and SpDCoV ISU73347. [S1 domain (in red), S2 domain (in green), RBD (in blue)].