Confluent microcarriers (Figure 3) , approximately 100 h post inoculation in the 1 l cultures and approximately 140-160 h in the 15 l cultures were infected with DISC-HSV at an MOI of 0.01 pfu cell −1 . The agitation was stopped and the microcarriers were allowed to settle out. The medium was then removed to waste. The 1 l cultures were washed by addition of 1 l of Dulbecco's PBS with agitation. The PBS wash was removed and this step repeated a further two times. The 15 l cultures were washed by addition of 10 l of Dulbecco's PBS with agitation. The PBS wash was removed to waste and this step was repeated a further two times. After washing, the original culture volume was replenished with serum free DMEM. The temperature during the infection period was decreased and maintained at 34 • C.