Physico-chemical properties of calf-diarrhea coronavirus

Replication of calf diarrhea coronavirus was not inhibited by 5-iodo-2′-deoxyuridine, indicating that the virus is an RNA virus. Sensitivity to ether and chloroform indicated that the virus is enveloped, and this was confirmed by electron microscopic observation of the virion. The virus was readily inactivated by trypsin and sodium deoxycholate. The virus was labile at 50°C in diluted medium, but readily stabilized in the presence of MgCl(2). It was stable at pH 5 and 7, while a slight loss of infectivity was observed at pH 3. The virus was readily filtered through membrane filters of 200 and 100-nm pore sizes, but not through 50-nm filters. The buoyant density of the virion in CsCl was estimated to be 1.25 g/ml.