Coronaviruses

Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS and COVID-19. In cows and pigs, they cause diarrhea; while in mice, they cause hepatitis and encephalomyelitis.

Betacoronavirus (β-CoVs or Beta-CoVs) is one of four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses. Member viruses are enveloped, positive-strand RNA viruses that infect mammals, including humans. The natural reservoir for betacoronaviruses are bats and rodents. Rodents are the reservoir for the subgenus Embecovirus, while bats are the reservoir for the other subgenera.

Alphacoronaviruses (Alpha-CoV) are members of the first of the four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses. They are positive-sense, single-stranded RNA viruses that infect mammals, including humans. They have spherical virions with club-shaped surface projections formed by trimers of the spike protein, and a viral envelope.

Deltacoronavirus (Delta-CoV) is one of the four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses. It is in the subfamily Orthocoronavirinae of the family Coronaviridae. They are enveloped, positive-sense, single-stranded RNA viruses. Deltacoronaviruses infect mostly birds and some mammals.

Gammacoronavirus (Gamma-CoV) is one of the four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses. It is in the subfamily Orthocoronavirinae of the family Coronaviridae. They are enveloped, positive-sense, single-stranded RNA viruses of zoonotic origin. Coronaviruses infect both animals and humans.