See text Alphacoronaviruses (Alpha-CoV) are members of the first of the four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses.

They have spherical virions with club-shaped surface projections formed by trimers of the spike protein, and a viral envelope.

Alphacoronaviruses infecting other mammal species have been much better studied, see List of Coronavirus live isolates.

The name alphacoronavirus is derived from Ancient Greek ἄλφα (álpha, "the first letter of the Greek alphabet"), and κορώνη (korṓnē, "garland, wreath"), meaning crown, which describes the appearance of the surface projections seen under electron microscopy that resemble a solar corona.

Glycoproteins and trimers form large surface projections which create the appearance of solar corona.

This genus, like other coronaviruses, has a spike protein with a type I fusion machine (S2) and a receptor-binding domain (S1).