Enhanced Production of Infectious Rotavirus in BSC-1 Cell Cultures by Various Factors in the Presence of Absence of Trypsin

Bovine rotavirus infectivity for continuous green monkey kidney (BSC-1) cells was enhanced in hypertonic medium and following incorporation of cortisol, retinoic acid and vitamin B12 into the cell culture maintenance medium. The virus yields produced under these conditions were similar whether obtained in the presence or absence of trypsin. Infectivity titres were increased following the incorporation of trypsin in the maintenance medium throughout the infection cycle but remained unchanged after trypsin treatment of infected cell extracts. Bovine rotavirus infectivity was not affected by incorporation of phytohaemagglutinin, thyroid gland extracts or foetal calf serum in similar experiments. Unexpectedly, serum promoted virus growth when used with cells treated with actinomycin D. Marked differences in the stability of the newly produced infectious rotavirus were observed, suggesting that cell permissiveness to rotavirus infection may vary following the physiological state of the host cell.