Serial propagation of astrovirus in tissue culture with the aid of trypsin.

Astrovirus could be serially passed at least 13 times in primary human embryo kidney (HEK) cells when 10 micrograms/ml of crystalline trypsin was incorporated in a serum-free maintenance medium. In the presence of trypsin the virus was also passed and adapted to a continuous line of rhesus monkey kidney cells (LLCMK2) and primary baboon kidney (PBK) cells in which it was passed 25 and 16 times respectively, without evidence of diminishing infectivity. Attempts to adapt the virus to other cell lines (Vero, Hep II, MRC-5, BHK and HRT-18) were unsuccessful. After 11 passages in HEK cells, a titration of virus grown in different concentrations of trypsin showed that virus propagation was still trypsin-dependent.