DNA vaccination using coexpression of cytokine genes with a bacterial geneencoding a 60-kDa heat shock protein

Coexpression of cytokine genes together with antigen-encoding genes in DNA vaccination vectors can increase humoral and cellular immune responses and may steer them in a Th1 or Th2 direction. In this study, the modulatory eff ect of interleukin (IL)-2, IL-4, and interferon (IFN)-gamma coexpressed wit h the 60-kDa heat shock protein (Hsp60) of Yersinia enterocolitica O:8 (Y-H sp60) was studied. DNA vaccination with y-hsp60 evoked specific humoral and cellular immune responses as well as reduction of the splenic bacterial lo ad upon challenge with Y. enterocolitica in a mouse infection model. Coexpr ession of IL-2 or IFN-gamma enhanced Y. enterocolitica-specific total IgG ( P < 0.05) and IgG2a antibody responses. Coexpression of IFN-<gamma> also im proved the proliferative T cell responses upon stimulation with Y-Hsp60. A reduction of the splenic bacterial load as compared with the plasmid encodi ng Y-Hsp60 only was found for the IFN-gamma coexpressing vector. Thus, coex pression of cytokine genes such as IFN-gamma in DNA vaccination vectors mig ht improve immunity and help to overcome the side effects of standard adjuv ants.