IFN-γ responses induced by immunization with recombinant baculoviruses. (A) Production of IFN-γ in the supernatant of splenocytes harvested from immunized mice after in vitro restimulation was determined by ELISA. Splenocytes of immunized mice were isolated 6 weeks after the primary immunization and incubated in vitro with E-DIII protein or NS3 protein for 72h. Data represent the mean concentrations of IFN-γ in the supernatant ± SD of the three independent experiments. (B) IFN-γ relative gene expression in splenocytes harvested from immunized mice after in vitro restimulation with or without E-DIII protein for 24h. RNA was extracted and subjected to RT-PCR. Relative quantity of IFN-γ mRNA expression was determined by relative quantitative real-time PCR using β-actin gene as housekeeping gene. The bars in graph denote the mean relative quantity of IFN-γ mRNA ± SD observed from three mice per group, each performed in triplicate. *, p<0.05; **, p<0.01 compared to the value for 109 PFU of Bac-G-EGFP (control virus)-immunized group.