PROS1 and infection: Despite the high sequence identity between the SARS-CoV-2 and the SARS-CoV in the open reading frame regions, the envelop spike protein (S-protein) [3], which mediates the infection of SARS-CoV via the human host protein ACE-2, has only about 80% shared sequence identity between the SARS-CoV and SARS-CoV-2 [1].