Coronaviruses

Abstract

Coronaviruses form a genetically divergent family of enveloped RNA viruses that includes important human and animal pathogens. Coronaviruses have the largest genomes (30 kb) among all known RNA viruses and use complex mechanisms to express and replicate their genome. Seven coronaviruses are known to infect humans. They have been classified as belonging to the genera Alphacoronavirus and Betacoronavirus, respectively, in the family Coronaviridae. Three of these viruses have a relatively recent history of zoonotic transmission to humans from different animal reservoirs, including severe acute respiratory syndrome coronavirus (SARS-CoV-2), the causative agent of COVID-19. Human coronaviruses are mainly associated with acute infections of the upper respiratory tract. Involvement of the lower respiratory tract and lung is less common and mainly restricted to patients with comorbidities or infections caused by one of the newly emerged betacoronaviruses (SARS-CoV, MERS-CoV, SARS-CoV-2). Coronavirus infections of the gastrointestinal tract and other organs do not play a major role, both clinically and numerically, except for a relatively small proportion of SARS-CoV-2 or MERS-CoV cases that progress into multiple organ manifestations with severe or even fatal disease outcome.

The present chapter is based on a text by John Ziebuhr published previously as a book chapter (in German) in “Medizinische Mikrobiologie und Infektiologie” (9th ed., S. Suerbaum et al. [eds.], Springer, 2020).