 It has, like other coronaviruses from genus "Betacoronavirus", subgenus "Embecovirus", an additional hemagglutinin esterase (HE) gene.The "Murine coronavirus" is a coronavirus that causes an epidemic murine illness with high mortality, especially among colonies of laboratory mice.Prior to the discovery of SARS-CoV, "M-CoV" (MHV, specifically) had been the best-studied coronavirus both "in vivo" and "in vitro" as well as at the molecular level.