Definition: A family of single-stranded RNA-containing viruses with three or four major antigens corresponding to each of the major viral proteins; some cause upper respiratory tract infections in humans similar to the “common cold”; others cause animal infections (infectious avian bronchitis, swine encephalitis, mouse hepatitis, neonatal calf diarrhea, and others). The viruses resemble myxoviruses except for the petal-shaped projections that give an impression of the solar corona. Virions are 120–160 nm in diameter, enveloped and sensitive to ether. Nucleocapsids are thought to be of helical symmetry; they develop in cytoplasm and are enveloped by budding into cytoplasmic vesicles. Coronavirus and Torovirus are the only recognized genera.
[L. corona, garland, crown]