COVID-19 Pathogen (SARS-Cov-2) Viral Evolution Leading to Increased Infectivity

OBJECTIVE: This study investigated changes in viral protein structures within the receptor binding domains (RBD) of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV), and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) viral particles, that may explain the evolution of increased infectivity. BACKGROUND: The emergence of severely pathogenic betacoronaviruses indicates increased infectivity and host range, possibly related to the evolution of the viral genome and subsequent proteins, specifically Coronavirus Spike Proteins that are involved in host receptor binding and host cell entry. METHODS: Amino acid sequences of the spike protein of each virus (SARS-CoV, MERS-CoV, and SARS-CoV-2) were obtained from the NCBI Virus Database and analyzed, along with their known receptors, for sequence changes and peptide properties to determine the characteristics of virus-receptor binding. Crystal structures were retrieved from the Protein Data Base for each virus and receptor and visualized using proteomic analysis software (PyMOL 2.1). RESULTS: SARS-CoV-2 displayed the largest magnitude difference (+32.4) in net charge between the virus and its receptor, angiotensin-converting enzyme 2, suggesting stronger electrostatic binding. SARS-CoV-2 also had the largest RBD (7140.29 angstroms2), indicating more surface area for interaction with the ACE2 receptor. CONCLUSION: Evolution of SARS-CoV-2 for a larger and more electrostatically “sticky” RBD compared to other pathogenic betacoronaviruses may contribute to observations of SARS-CoV-2 having stronger or more stable binding, leading to transmissibility and infectivity. Further investigation of conserved genomic regions between these viruses may facilitate the development of viable vaccines and treatments.