Immunization with Naked DNA Coexpressing Antigen and Cytokine via IRES

Inoculation of plasmid DNA vectors encoding immunogenic proteins induce humoral as well as cell-mediated immune responses. Protection against challenge with pathogens has provided protective immunity in several instances in animal models. (1 ,2 ). DNA vaccines allow the simultaneous expression of antigens and immune-stimulatory cytokines via an internal ribosomal entry site (IRES). Here we describe the construction of a DNA vaccine against malignant melanomas using: (i) the tumor-associated antigen gp100 (or pmel17), known to be over-expressed in many malignant melanomas (3 ,4 ), and (ii) the granulocyte macrophage stimulating factor (GM-CSF) which has been shown to have a stimulatory effect on humoral and cellular immune responses (5 ).