Severe acute respiratory syndrome coronavirus (SARS-CoV-2) is a positive-sense single-stranded RNA virus that can infect human epithelial cells through interaction with the human ACE2 receptor. The viral membrane protein, spike (S) glycoprotein, has been identified to bind human ACE2 receptors and mediate cell entry. The spike protein is composed of 2 subunits, S1 and S2, responsible for receptor recognition and cell membrane fusion, respectively.