Time course of T-cell responses to AAV-1 capsid measured by IFN-γ ELISpot. Each horizontal bar represents an individual subject; time after intramuscular administration (in weeks) is indicated by the vertical lines. Gray bars indicate a negative ELISpot result; red bars indicate a positive ELISpot result. A time point was considered positive when the average SFU/10⁶ PBMCs was higher than 3 × the medium control and at least 50 SFU/10⁶ PBMCs for both the AAV-1 peptide pools and the AAV-1 empty particles antigens. The vector dose, in genome copies per kilogram (gc/kg), received by the subjects in the 2 cohorts is indicated on the left of the graph. *Negative for AAV-1 empty capsids.