Abstract
By using cultured cells, an attempt was made to isolate virus from the feces of a foal infected with rotavirus. The fecal sample used was supplied by Dr. J. C. Bridger, of the Institute for Research on Animal Diseases, the U. K. A fecal filtrate was mixed with an equal quantity of a solution containing 4μg/ml of trypsin. The mixture was inoculated into MA-104 (Macacus rhesus monkey kidney) cells and incubated in a maintenance medium containing 2μg/ml of trypsin. Consequently, virus (BI strain) was isolated with distinct cytopathic effect (CPE). It was capable of being successively passaged in the cultured cells. The multiplication of virus was better in rotary culture than in stationary culture. Especially, the multiplication of virus in the 1st cell passage was strongly influenced by rotary culture. In electron microscopic observation, typical rotavirus particles were detected in a concentrated suspension prepared from the infected fluid of the cell cultures. The infected cells showed a specific fluorescence when stained with fluorescein-labeled antibody prepared from anti-neonatal calf diarrhea virus (NCDV) serum. Therefore, the isolated virus was identified as rotavirus. In the cross serum neutralization test, the isolated virus did not cross-react with NCDV. From these results, it was revealed that foal rotavirus contained in the feces could easily be isolated in MA-104 cells by treating the viral suspension with trypsin and adding trypsin to the maintenance medium.
