The global outbreak of SARS in 2002-2003 was caused by the infection of a new human coronavirus SARS-CoV. The new outbreak of 2019-nCoV also is caused by a new zoonotic, now, human betacoronavirus born in Wuhan.

The infection of SARS-CoV and the new Wuhan 2019-nCoV like others coronaviruses is mediated mainly through the viral surface glycoproteins, which consist of two subunits and form trimer spikes on the envelope of the virions. One subunit is the stalk fusion domain and the other a globular recognition domain. The coronavirus spike is the largest class I fusion known and displays structural similarities to the spike proteins of influenza and HIV.

The spike (S) glycoprotein on the coronavirus envelope is responsible for host cell attachment, receptor binding, and for mediating host cell membrane and viral membrane fusion during infection.

Coronaviruses are a large group of highly diverse, enveloped, positive-sense, single-stranded RNA viruses that infect many mammalian and avian species. Currently, six, now seven coronavirus strains that are able to infect humans have been identified. Among them, alphacoronaviruses HCoV-229E and HCoV-NL63 and lineage A betacoronaviruses HCoV-OC43 and HCoV-HKU1 usually cause mild and self-limiting upper respiratory tract infection. 2019-nCoV from Wuhan is the new family member.

There are still no approved antiviral drugs and vaccines to treat and prevent the infections of SARS-CoV and MERS-CoV.