Coronaviruses – How Protein Interactions Changed Our Perception Of The World

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the third, following SARS-CoV (Severe Acute Respiratory Syndrome Coronavirus) and Middle East Respiratory Syndrome-CoV (MERS), zoonotic coronavirus that has crossed the species barrier in XXI century resulting in the development of serious human infection termed COVID-19 (coronavirus disease-19). However, there are still many unanswered questions about its transmissibility and pathogenesis, what impelled us to gather the most recent facts about the nature of coronaviruses. At first we introduced the basic information about coronavirus taxonomy, structure, and replication process to create the basis for more advanced consideration. We also put across the molecular basis of the strategy used by coronaviruses to cross the species barrier. In the following part of this review we focused on the interactions between the virus and the receptor on the host cell, as this stage is the critical process determining the species and tissue tropism, as well as clinical course of infection. The special attention was paid to the cellular receptors interaction with S protein of different CoVs (dipeptidyl peptidase IV and angiotensin-converting enzyme 2) as well as the cellular proteases involved in proteolysis of this protein. These factors determine the virus entry and replication, thus even the fine quantitative or qualitative difference in their expression may be crucial for outcome of infection. We also considered the host immune response and viral evasion mechanisms which would be helpful to understand COVID-19 pathogenesis. We wish the information provided by this review may be helpful to understand virus biology and to develop efficient therapeutic and preventive strategies.