COVID-19 Pathogen Viral Evolution Leading to Increased Infectivity.

ABSTRACT

Objective This study investigated changes in viral protein structures within the receptor-binding domains (RBDs) of the viral particles of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 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 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, along with the sequences for their known receptors, and analyzed for sequence changes and peptide properties to determine the characteristics of the virus-receptor binding. Crystal structures were retrieved from the Protein Database for each virus and receptor and visualized using proteomic analysis software (PyMOL 2.1) (Schrödinger, Inc., New York, USA). Results SARS-CoV-2 displayed the largest magnitude difference (+32.4) in net charge between the virus and its receptor, angiotensin-converting enzyme 2 (ACE2), suggesting stronger electrostatic binding. SARS-CoV-2 also had the largest RBD (7140.29 Å2), indicating more surface area for interaction with the ACE2 receptor. Conclusion The 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 a stronger or more stable binding, leading to increased transmissibility and infectivity. Further investigation of conserved genomic regions between these viruses may facilitate the development of viable vaccines and treatments.