Next, we showed that the percentages of CD4+ or CD8+ T-cells that produced IFN-γ after stimulation with VZV IE62, VZV IE63 or VZV gE did not significantly differ between different time points after re-exposure to chickenpox in grandparents, nor was there a significant difference with those observed in the control participants. The gene discussed is IFNG; the disease is chickenpox.