The proteins, enzymes and ligands of the Covid-19 virus play a vital role in infection. The virus is contagious and spreads from the droplets of the infected person. The outer spike like glycoprotein have cellular attachment factors like the angiotensin-converting enzyme 2 (ACE2) and cellular protease TMPRSS2. They are responsible for the attachment of the virus to the host cell.

Once the virus gets attached, the genome is introduced into the host cell. The RNA replicates, transcribe and translates to encode the proteins for infection. Majorly the epithelial cells of the respiratory tract get affected first. The immune response of the body to the infection causes inflammation of the cells.