The evil role of spike in the coronaviruses: structure, function and evolution

Since the beginning of the 21st century, coronaviruses that originated from animals to human have been the cause of several deadly pneumonia epidemics including SARS, MERS disease, and now COVID-19 which has become a worldwide pandemic. The emergence of these acute respiratory syndromes emphasizes the cross-species transmission of coronaviruses and their prevalence in humans. Coronaviruses contain a surface- spike protein (S) that initiates infection by recognizing its receptor and attaching to the membrane, which is a key step in the host specificity and intergenerational transmission. To date, no specific treatment or vaccine against any of the seven human coronaviruses has been approved. This underscores the importance of exploring the mechanisms governing the virus entry and intergenerational transmission. This review article discuss the mechanism of infection used by coronaviruses by focusing on the features of the S protein and its receptor binding characteristics in different species. In addition, protease processes involved in the onset of infection was considered to provide a complete picture of their role in the coronavirus replication cycle. Finally, treatments based on the interaction of S-protein and ACE2 receptor were described.