The amino acids 736-761 of the MERS-CoV spike protein induce neutralizing antibodies: implications for the development of vaccines and antiviral agents.

Based on a bioinformatics analysis of the Middle East respiratory syndrome coronavvirus (MERS-CoV) S protein, we synthesized a panel of peptides coupled to keyhole limpet haemocyanin and used them to raise antibodies in rabbits. In addition, the recombinant receptor-binding domain (RBD) was used to raise polyclonal antibodies in mice. All of the antibodies raised by S-peptide immunisation were specific and sensitive for S protein expressed in transfected cells in the indirect immunofluorescence assay or Western blotting. The RBD efficiently elicited neutralizing antibodies against MERS-CoV by blocking viral entry at the binding step. Furthermore, we found that the SP3 peptide, corresponding to amino-acid residues 736-761 of the S protein, elicited robust neutralizing activities by blocking viral entry at the postbinding and membrane fusion steps. We conclude that amino-acid residues 736-761 of the S protein carry neutralizing epitopes that may be used in the development of vaccines and antiviral agents against MERS-CoV.