Receptor-binding domain as a target for developing SARS vaccines.

A decade ago, severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) caused a global pandemic with a mortality rate of 10%. Reports of recent outbreaks of a SARS-like disease caused by Middle East respiratory syndrome coronavirus (MERS-CoV) have raised serious concerns of a possible reemergence of SARS-CoV, either by laboratory escape or the presence of a natural reservoir. Therefore, the development of effective and safe SARS vaccines is still needed. Based on our previous studies, we believe that the receptor-binding domain (RBD) in the S1 subunit of the SARS-CoV spike (S) protein is the most important target for developing a SARS vaccine. In particular, RBD of S protein contains the critical neutralizing domain (CND), which is able to induce highly potent neutralizing antibody response and cross-protection against divergent SARS-CoV strains. Furthermore, a RBD-based subunit vaccine is expected to be safer than other vaccines that may induce Th2-type immunopathology. This review will discuss key advances in the development of RBD-based SARS vaccines and the possibility of using a similar strategy to develop vaccines against MERS-CoV.