Growth of Ibaraki virus in suspension culture of HmLu-1 cells.

The established hamster lung cell line, HmLu-1 cells could grow in a suspended state. The initial cell count, 40 X 10(4)/ml, increased to 200 X 10(4)/ml on the 4th day of culture. The suspension culture of HmLu-1 cells was proved satisfactory for propagation of Ibaraki virus. The viral titer reached a maximum of 10(6.75) TCID50/0.1 ml. The input multiplicity ranging from 0.003 to 3.0 exerted no influence on the final yield of the virus. The optimal pH value of initial culture ranged from 6.8 to 7.6. In comparison of virus yield per cell among the suspension culture and two methods of monolayer culture in stationary and rolling condition, there was no noticeable difference in it among the three methods. The cell population per unit volume was the largest and, therefore, virus titer in the culture fluid the highest in the suspension culture of the three methods.