Proliferation and IFN-γ secretion of splenic cells from immunized C3H mice in response to inoculation with recombinant JEV NS1 protein and SA14-14-2. Splenocytes isolated from mice immunized with PBS, aqueous NS1, adjuvanted NS1, DMEM with 3% FBS (complemented DMEM) and attenuated virus SA14-14-2, were stimulated with purified NS1. A: Splenocyte proliferation. The proliferation stimulation index (SI) was defined as the ratio of stimulated cells to unstimulated cells. B: IFN-γ secretion. The IFN-γ production of splenic cells was quantified over a period of five days. Three mice were used for each group. The SI and IFN-γ concentration were analyzed by Student’s t-test. P < 0.05 was considered to be significant. *, significant difference.