The receptor binding domain of the new Middle East respiratory syndrome coronavirus maps to a 231-residue region in the spike protein that efficiently elicits neutralizing antibodies.

The spike (S) protein of the recently emerged human Middle East respiratory syndrome coronavirus (MERS-CoV) mediates infection by binding to the cellular receptor dipeptidyl peptidase 4 (DPP4). Here we mapped the receptor binding domain in the S protein to a 231-amino-acid fragment (residues 358 to 588) by evaluating the interaction of spike truncation variants with receptor-expressing cells and soluble DPP4. Antibodies to this domain--much less so those to the preceding N-terminal region--efficiently neutralize MERS-CoV infection.