Fig. 1.

Structure of SARS-CoV-2.

SARS-Cov-2 belongs to the family of RNA viruses with other members including SARS-CoV and MERS-CoV. These viruses have characteristic crown-like-protrusions spike proteins (S) used to gain entry into the host cells and thereby inflict the respiratory disease COVID-19. ACE-2 is the host receptor mediating this process of internalization. Protease ACE-2 mediates the cleavage of spike protein which then releases an epitope that allows the subsequent fusion of the virus with the host cells. Inside the host, SARS-CoV-2 thrives in epithelial cells of lungs, kidneys, small intestines, and endothelial cells within arteries and veins. The viral genome is composed of a positive sense (+) RNA (~30 kb). The coronavirus group-2 also has hemagglutinin–acetylesterase (HE) glycoprotein that has an affinity to bind with sugar moieties on the cell membranes. The RNA-dependent-RNA polymerase can switch templates during the replication, a highly error-prone process. The virus envelope protein plays a central role in virus morphogenesis and assembly and its interaction with other viral proteins. The nucleocapsid (N), Spike (S), Envelope (E), and Membrane (M) structural proteins embedded into a lipid bilayer are the characteristic hallmarks of the SARS-CoV-2. For the virus to replicate into the host cells in inserts its RNA into the cells like monocytes and macrophages and takeovers the cellular machinery to produce new virions.