S1 domain of the porcine epidemic diarrhea virus spike protein as a vaccine antigen

Makadiya, Niraj; Brownlie, Robert; van den Hurk, Jan; Berube, Nathalie; Allan, Brenda; Gerdts, Volker; Zakhartchouk, Alexander

The size of PEDV genomic RNA is about 28 kb, and contains seven open reading frames (ORFs) encoding viral proteins: 1A, 1B, spike (S), ORF3, envelope (E), membrane (M) and nucleocapsid (N). The S protein is present at the outer surface of the virion and is 1386 amino acid long [16] . The spike protein of coronaviruses forms trimers and plays an important role in the virus attachment and in virus-cell membrane fusion [17] . Porcine aminopeptidase N has been demonstrated to be a functional receptor for the PEDV coronavirus [18] . The S protein of PEDV is a class I membrane glycoprotein consisting of two subunits: the N-terminal S1 and the C-terminal S2. Cleavage of spike protein into S1 and S2 is an essential event in the cellular entry for wild-type PEDV virus but not for cell culture adapted PEDV [19] . Proteolytic cleavage of spike protein in PEDV needs trypsin [19, 20] . Several neutralizing epitopes have been identified on the S protein sequence [21] [22] [23] , and the recombinant S1 protein was previously shown to have protective activity in piglets [24] .