Fig. 2.

T-cell mediated response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).The virus gains entry into the human body upon binding with the hACE2 receptor present on the cell membrane of various cell types. As soon as the virus begins to replicate, the immune cells are alerted. This is followed by endocytosis of the virus into dendritic cells and antigen degradation. The antigen fragments are then presented on the cell surface by MHC class I and MHC class II molecules facilitating its binding with a T-cell. When CD8 + T-cells bind to antigens, MHCI molecules present the antigen—this causes CTLs to multiply and target host cells infected with the pathogen, ultimately leading to their death. If CD4 + T-cell binds, it eventually activates B-cells which secrete neutralizing antibodies that associate with different regions of the virus thereby preventing it from binding with the ACE2 receptor expressed on various cell surfaces