IMMUNOLOGY

Detailed explanation-1: -SARS-CoV-2 is highly homologous to SARS-CoV and both use ACE2 as their entry receptor (2, 9). Further structural studies demonstrated that both SARS-CoV-2 and SARS-CoV used their spike protein RBD domain to interact with ACE2 in similar binding modes (11).

Detailed explanation-2: -SARS-CoV-2 S protein binds to the ACE2 receptor at the surface of host cells, initially through the S1 RBD. S1 is then shed from the viral surface, allowing S2 to fuse to the host cell membrane.

Detailed explanation-3: -Cell-to-Cell Transmission of SARS-CoV-2 Is Refractory to Neutralizing Antibody and Convalescent Plasma. One important feature of the virus cell-to-cell transmission is evasion of host immunity, particularly neutralizing antibody-mediated response.

Detailed explanation-4: -According to the recent research, SARS-CoV and SARS-CoV-2 conjugate with ACE2 receptors on the lung epithelial membrane and enters the cell thereafter replicates and results in downregulation of these receptors. The physiological function of these receptors is to degrade angiotensin II.