Seven type of CoVs have been identified to cause human disease [107]. The two highly pathogenic viruses, SARS-CoV and MERS-CoV, cause severe respiratory syndrome in humans. The other four human CoVs (HCoV-NL63, HCoV-229E, HCoV-OC43 and HKU1) induce only mild upper respiratory diseases, although some of them can cause severe infections in infants, young children, and elderly individuals [4,108]. The latest one is SARS-CoV-2. It has been reported that SARS-CoV-2 shared almost 80% of the genome with SARS-CoV [11]. Our results also showed that almost all encoded proteins of SARS-CoV-2 are homologous to SARS-CoV proteins (Table 2). Hence, clinical drugs and therapies for treating SARS may be used as a reference for COVID-19 treatment [74].