Coronaviruses
are enveloped RNA viruses that are spherical in shape and characterized by
crown-like spikes on the surface under an electron microscope, hence the name.
This type of virus can be further divided into four subgroups: alpha, beta,
gamma, and delta. There are seven human coronavirus strains, including two
alpha coronaviruses (HCov-229E and HCoV-NL63), two beta coronaviruses
(HCov-HKU1 and HCov-OC43), MERS-CoV, SARS-CoV, and the newly discovered
SARS-CoV-2. Coronaviruses are major pathogens in both humans and other animals.