Covid-19 coronavirus spike protein, illustration

Covid-19 coronavirus spike protein, illustration. Molecular models of the structures and domains of the spike protein of the Covid-19 coronavirus. A coronavirus particle (yellow, upper right) is also shown (not to scale). 2019-nCoV makes use of a densely glycosylated spike (S) protein to gain entry into host cells. The S protein is a trimeric class I fusion protein that exists in a metastable prefusion conformation that undergoes a dramatic structural rearrangement to fuse the viral membrane with the host-cell membrane. Covid-19, which emerged in Wuhan, China, in December 2019, is a mild respiratory illness that can develop into pneumonia and be fatal in some cases. It is caused by the SARS-CoV-2 (previously 2019-nCoV) coronavirus. As of March 2020, the virus has spread to many countries worldwide and has been declared a pandemic. Over 100,000 have been infected with several thousand deaths.