The indicated virus-specific T-cell immune responses in immunized mice by ELISPOT assay. The mean number of spot-forming cells (SFCs) of indicated virus-specific IFN-γ-producing cells per million lymphocytes from Balb/c mice pre-immunized with FI-RSV, rLong or rLong-∆G-EGFP was shown with black bars, and the IL-2-producing cells per million lymphocytes from corresponding pre-immunized Balb/c mice was shown with gray bars. The IFN-γ and IL-2 ELISPOT assays in FI-RSV, rLong or rLong-∆G-EGFP groups were performed with the stimulation of the indicated long virus antigen (40 μg/ml) for 16-20 h while the concentration of positive stimulus PMA or ConA is 10 ug/ml, the negative control was stimulated by PBS. Experiments were performed with three mice per group. The data were analyzed by t test, and the differences were statistically significant for IFN-gamma, but not significant for IL-2 between rLong and rLong-∆G-EGFP.