Several different procedures have been developed to deliver essential genes to an organism by viral vectors. Some reports have already been published demonstrating the potential to use enteroviruses as transfer vehicles. One application of these viral vectors is the organ-specific expression of immunoregulatory cytokines. It has been shown previously that local expression of interferon-gamma (IFN-gamma) by the recombinant coxsackievirus CVB3/IFN-gamma conferred protection against virus-caused disease via direct and indirect mechanisms. Using a murine model of CVB3-induced myocarditis, other aspects of the CVB3/IFN-gamma application as a vaccine were studied concerning route of administration, age, and presence of a pre-existing immune response.