Figure 2.

Schematic diagram of the MERS-CoV S glycoprotein anchoring to the virus envelop ²⁷. The MERS-CoV S glycoprotein has been a target for developing MERS vaccines. S glycoprotein gives rise to substantial titers of neutralizing antibodies, and the antigens in subunit vaccines have been often manipulated. The S glycoprotein attaches via the S glycoprotein RBD to the host cell receptor dipeptidyl peptidase 4 (DPP4) ²⁸. It is possible to divide the S glycoprotein into two subunits (S1 and S2). The RBD includes the subunit S1. The S2 subunit contains (HR1 and HR2), which are used by MERS-CoV for membrane fusion and host cell entry. The S glycoprotein is portrayed as a class I fusion protein and forms a trimmer.