{HEAD ~ The method} 1, wherein {TAIL ~ the titer} of virus produced by the infected cells is at least 108 TCID50/ml 
wherein
{ HEAD ~ The method } 1 , wherein { TAIL ~ the titer } of virus produced by the infected cells is at least 108 TCID50 / ml
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH