A NEW CORONA-LIKE VIRUS CAUSING DIARRHEA IN INFANT MICE (DVIM)
MORPHOLOGICAL AND BIOLOGICAL CHARACTERISTICS
1978 Volume 28 Issue 1 Pages 10-18
Details
1978 Volume 28 Issue 1 Pages 10-18
Studies were made on the morphological and biological characteristics of the diarrhea virus of infant mice (DVIM) isolated by Sato et al.
When BALB/c-3 T3 cells were inoculated with the virus, infectivity was detected in the cytoplasm and in the culture fluid four and six hours after inoculation, respectively. The maximum virus titer in the culture fluid was 105.3TCID 50/0.1ml, reached eight to ten hours after inoculation.
DVIM was an enveloped virus 100nm in diameter covered with two types of projections. The projection of one type was club-shaped and 20nm in length. The projection of the other type was small, granular, and 5nm in size. It may possibly be the remaining part of the 20nm projection. The envelope was about 10nm in thickness. The inner structure of the virion was not clarified by the electronmicroscopic negative staining technique.
DVIM agglutinated rat and mouse red blood celles at a low temperature in three to four hours of incubation. The 20nm projections of DVIM disappeared readily in the process of purification or sonication (20KHz). The 5nm projections, however, remained firmly attached to the envelope, suggesting that they might probably be related to the hemagglutinating activity.
DVIM induced the formation of syncytia in BALB/c-3 T3 cell cultures within ten hours after inoculation. Mouse red blood cells were adsorbed by the syncytium at a low temperature and then released after incubation at a high temperature (37°C or room temperature). The mechanism of this phenomenon was somewhat similar to that of hemadsorption of myxovirus.
By immuno-fluorescent microscopy, viral antigens were found on the syncytium. Virus-like particles were observed on the surface of the syncytium by scanning electron microscopy.
DVIM may be classified as a virus related to the coronaviridae for convenience sake. Its characteristics, however, are quite different from those of any of the existing members of the coronaviridae.
