Most SARS-CoV and MERS-CoV vaccines developed thus far are based on the inactivated or live attenuated viruses, DNAs, proteins, nanoparticles, viral vectors, including virus-like particles (VLPs) (Zeng et al., 2004; Jiang et al., 2005; Liu et al., 2005; Du et al., 2009a, 2016b; Pimentel et al., 2009; Al-Amri et al., 2017). Each vaccine type has different advantages and disadvantages. For instance, inactivated and live-attenuated virus-based vaccines are vaccine types developed using the most traditional approaches. Although they generally induce highly potent immune responses and/or protection, the possibility for incomplete inactivation of viruses or recovering virulence exists, resulting in significant safety concerns (Zhang et al., 2014). Also, these traditional vaccines may induce the antibody-dependent enhancement (ADE) effect, as in the case of SARS-CoV infection (Luo et al., 2018b). Similarly, some viral-vectored vaccines can elicit specific antibody and cellular immune responses with neutralizing activity and protection, but they might also induce anti-vector immunity or present pre-existing immunity, causing some harmful immune responses. Instead, DNA and nanoparticle vaccines maintain strong safety profile; however, the immunogenicity of these vaccines is usually lower than that of virus- or viral vector-based vaccines, often requiring optimization of sequences, components, or immunization routes, inclusion of appropriate adjuvants, or application of combinational immunization approaches (Zhang et al., 2014).