Cytokine detection in splenocyte culture supernatants from vaccinated mice. Splenocyte samples (10 mice per group) isolated from the spleens of vaccinated mice on day 14 after the last immunization against the MEAP. After 72 h, the supernatants were collected to examine the levels of the Th1- type cytokine IL-2, IFN-γ and the Th2-type cytokine IL-4 using commercially available murine cytokine EIA kits. All the measurements were made in triplicate, with the mean ± standard error (SE) shown. P < 0.05 compared with groups immunized with PBS or inactivated vaccine.