emat opo iet ic ▁stem ▁cell ▁trans plant ation ▁that ▁has ▁proven ▁to ▁be ▁un success ful . ▁ ▁It ▁is ▁a ▁treatment ▁that ▁has ▁been ▁effective ▁in ▁prevent ing ▁and ▁tre ating ▁vir al ▁in fe ctions ▁after ▁H S CT . ▁V ST ▁ther apy ▁uses ▁active ▁don or ▁T - cell s ▁that ▁are ▁isolated ▁from ▁all ore active ▁T - cell s ▁which ▁have ▁proven ▁imm unity ▁against ▁one ▁or ▁more ▁vir uses . ▁Such ▁don or ▁T - cell s ▁often ▁cause ▁ac ute ▁gra ft - vers us - host ▁disease ▁( GV HD ), ▁a ▁subject ▁of ▁on going ▁investigation . ▁V ST s ▁have ▁been ▁produced ▁primarily ▁by ▁ex - v ivo ▁cult ures ▁and ▁by ▁the ▁expansion ▁of ▁T - ly m ph ocy tes ▁after ▁stim ulation ▁with ▁vir al ▁ant ig ens . ▁This ▁is ▁carried ▁out ▁by ▁using ▁don or - der ived ▁ant igen - present ing ▁cells . ▁ ▁These ▁new ▁methods ▁have ▁reduced ▁culture ▁time ▁to ▁ 1 0 – 1 2 ▁days ▁by ▁using ▁specific ▁cy tok ines ▁from ▁adult ▁don ors ▁or ▁virus - na ive ▁cord ▁blood . ▁ ▁This ▁treatment ▁is ▁far ▁quick er ▁and ▁with ▁a ▁substantial ly ▁higher ▁success ▁rate ▁than ▁the ▁ 3 – 6 ▁months ▁it ▁takes ▁to ▁carry ▁out ▁H S CT ▁on ▁a ▁patient ▁diagn osed ▁with ▁a ▁primary ▁imm un ode fic iency . ▁T - ly m ph ocy te ▁ther ap ies ▁are ▁still ▁in