[Isolation and cultivation of a swine rotavirus]

A swine rotavirus capable of inducing the cytopathic effect was isolated in a roller culture of Macaca rhesus kidney cells (line MA-104) after two preliminary passages in gnotobiotic piglets and colostrum-free piglets, and the isolate was designated strain K. For virus isolation, fecal specimens were treated with trypsin, and besides, trypsin was added into the maintenance medium. After 20 passages in MA-104 cell culture the swine rotavirus was adapted to pig embryo kidney cell cultures (SPEV line) in which the maximum virus accumulation, 8.0 log TCD50/ml, was achieved within 24 hours after inoculation. The virus accumulation was most marked in the presence of 10 micrograms/ml trypsin in the maintenance medium. In the roller culture, the virus multiplied to a much higher titre (approximately 100-fold) than in the stationary culture. In the course of passages the virus was shown to lose its pathogenic properties. A scheme of swine rotavirus virion structure is suggested on the basis of ultramicroscopic studies.