Morphological and biological properties of a new coronavirus associated with diarrhea in infant mice

Biological and morphological properties of a virus, isolated from the intestine of infant mice with clinical signs of diarrhea and designated as diarrhea virus of infant mice (DVIM), were examined. The first infective virus was detected on the cells 4 hours post infection, followed by rapid release of the virus into the culture fluids. Virus-induced syncytia in BALB/c-3T3 cell cultures caused hemadsorption at 4° C and viral antigens were shown to be located in the cytoplasm of the syncytia by immunofluorescent techniques. By scanning electron-microscopy, budding virus-like particles were detected on the surface of virus-induced syncytia. Morphologically the virus was shown to be enveloped and approximately 100 nm in diameter. Two types of projections were demonstrated, one type of projection was club-shaped, 20 nm in length and the other type was small, granular, 5 nm in length. The latter type of projection might be the basal part of the clubshaped type and related to the hemagglutinating activity.