GM-CSF and IL-2 as adjuvant enhance the immune effect of protein vaccine against foot-and-mouth disease

Background: Cytokines as molecular adjuvant play a critical role in differentiation of effector T cell subsets and in determination of the magnitude of the response after vaccination. In this study, we investigated the effects of GM-CSF and IL-2 as adjuvant on the immune responses of VP1 recombinant protein as a model antigen for foot and mouth disease. Results: Six expression plasmids were constructed and expressed in E. coli BL21. In guinea pigs, the immunological and molecular effects of the fusion proteins were determined by ELISA, LPA, DTH and semi-quantitative Reverse Transcriptase PCR (RT-PCR). The data revealed that IL-2 and GM-CSF as adjuvant of VP1 could stimulate both humoral and cell-mediated immune response. Interestingly, IL-2 and GM-CSF, either as a co-expressed protein or as a mixture of two single proteins, showed much better adjuvant effects than that of single one. Conclusions: IL-2 and GM-CSF could be used as a potential adjuvant for VP1 and had synergistic effect when co-expressed or mixed with VP1.