Cytokine production profiles. Splenocytes from groups of immunized mice were stimulated with recombinant VP1 protein for 72 h. Concentrations of (A) IFN-γ. (B) IL-4. (C) IL-5. (D) TGF-β in the culture supernatants were determined by ELISA. The concentration values of cytokines were expressed as mean ± SD. (* P < 0.05, ** P < 0.01).