A review of COVID-19: Molecular basis, diagnosis, therapeutics and prevention

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the confirmed viral pathogen of COVID-19, a pandemic originated from Wuhan, China at the end of 2019. Since then, SARS-CoV-2 has rapidly spread across the globe with over 8 million confirmed cases and more than 430.000 deaths worldwide as of mid-June 2020. Similar to other strains of coronavirus, the envelope of SARS-CoV-2 comprises of three structural proteins: S protein (spike), E protein (envelope) and M glycoprotein (membrane). SARS-CoV-2 capsids are spherical or pleomorphic. Each capsid contains a positive-sense single-stranded RNA (+ssRNA-Class IV-Baltimore) associated with nucleoprotein N. The viral RNA genome is approximately 30 kb in length and contains 14 open reading frames (ORFs). The binding affinity of the viral S protein to the ACE2 (angiotensin-converting enzyme 2) receptor facilitates the attachment of SARS-CoV-2 to human epithelial cells. Upon binding, SARS-CoV-2 spike protein is cleaved and activated by TMPRSS2 (transmembrane protease, serine 2) or by cathepsin L at the cleavage site S2', and also by furin at the cleavage site S1/S2. The furin cleavage motif RR_R is a notable feature, firstly found in SARS-CoV-2 S protein, which may increase virus transmission rate. This feature and many others might result from several evolution events in SARS-CoV-2 genome. These events could occur when coronaviruses, including SARS-CoV-2, spread from one host to another. They can be causative to high virulence and transmission rate of future coronavirus strains, which may require the development of newer vaccine generations. To understand of SARS-CoV-2’s structure, infection mechanism, diagnosis, treatment, and vaccine development strategies, a review of current literature is of highly importance to disease control in Vietnam.