Chapter 2 - SARS-CoV-2: Structure, Pathogenesis, and Diagnosis

Abstract

The betacoronavirus SARS-CoV-2 is a positive-sense single-stranded RNA virus with a genome that extends to approximately 30 kilobases. Its genome encodes critical structural proteins spike (S), envelope (E), membrane (M), and nucleocapsid (N), in addition to several open reading frames that code for accessory and nonstructural proteins that play a role in immune evasion, disruption of host cellular processes, viral replication, and transcription. As the virus continually evolves, novel mutations in the SARS-CoV-2 spike protein have been observed to confer immune-evasive properties and enhanced binding to the host cell receptor angiotensin-converting enzyme-2. SARS-CoV-2 initially infects epithelial cells in the respiratory tract, where infection is associated with a hyperinflammatory response and a massive recruitment of immune cells, which has the potential to induce extensive organ damage. To prevent the transmission of this harmful pathogen, early and accurate diagnosis is vital. This chapter provides an introduction to SARS-CoV-2 from a molecular biology perspective, including a discussion of the functions of the various proteins encoded by its genome, the mechanisms by which the virus infects its human hosts and causes disease, and a summary of the diagnostic methods used to detect infection by the virus.