Anti-HPIV3 and HHV6 T-cell activity and clinical response. (A) Anti-HPIV3 antigen (matrix, NP) T-cell response of the HPIV3-specific VST products as detected by IFN-γ ELISpot assay. Anti-HPIV3 antigen T-cell response in the recipient PB and detection of HPIV3 by PCR of a nasal swab post-VST infusion for prophylaxis against HPIV3 (B-E). (F) Anti-HHV6 antigen (U54, V90) T-cell response of the HHV6-specific VST products as detected by IFN-γ ELISpot assay. (G-J) Anti-HHV6 antigen T-cell response and HHV6 viral load (copies per milliliter) in the recipient PB post-VST infusion for prophylaxis against HHV6. HHV6, human herpes virus 6; HPIV3, human parainfluenza virus 3; NP, nucleocapsid: PCR, polymerase chain reaction; SFU, spot forming units.