ISOLATION AND SERIAL PROPAGATION OF HUMAN GROUP-C ROTAVIRUSES IN A CELL-LINE (CACO-2)

Rotaviruses were detected via electron microscopy in fecal specimens c ollected from school children during an outbreak of diarrhea and from a sporadic case in 1993 in Japan. All of the viruses were found to bel ong to human group C rotavirus by reverse passive hemagglutination ass ay (RPHA). These viruses replicated well in a human colon carcinoma (C aCo-2) cell line cultured in the presence of trypsin (4 mu g/ml). This report demonstrates that human group C rotaviruses can be propagated efficiently in a cell line cultured in the presence of trypsin. The in fected cells did not show any apparent cytopathic changes. However, vi rus was detected in the cell cytoplasm by immunofluorescence (IF) stai ning and in the culture supernatant by RPHA. On the basis of immune el ectron microscopy (IEM), virus particles collected from infected CaCo- 2 cell cultures were confirmed to aggregate specifically with anti-hum an group C rotavirus antibody. The electrophoretic patterns of RNA seg ments extracted from viral particles found in the fecal specimens or i nfected cells were identical to those of human group C rotavirus. Thes e results indicated that human group C rotaviruses were the causal age nt of the diarrhea outbreak. (C) 1996 Wiley-Liss, Inc.