Cardiovascular disease is one of the major causes of human death and has been linked to many different risks including viral infections. Coxsackievirus B3 (CVB3) is one of the most important pathogens responsible for virus-induced myocarditis. Cytokines are normally involved in the control of CVB3 replication and pathogenesis. Among them, interferon-gamma (IFN-gamma) in particular is highly protective against CVB3. A novel strategy to circumvent virus-caused heart disease is based on the development of cytokine-expressing recombinant virus vectors. Using in vitro co-culture experiments, the release of IFN-gamma by the recombinant virus variant CVB3/IFN-gamma activates the expression of the inducible nitric oxide synthase (iNOS) in CVB3 non-susceptible murine macrophages and the release of nitric oxide (NO), which reduce coxsackieviral replication directly. In addition, the expression of IFN-gamma by CVB3/IFN-gamma contributes to protect mice from lethal infections by iNOS induction in murine peritoneal macrophages, viral load reduction, and pancreatic tissue protection.

The induction of apoptosis during coxsackievirus B3 (CVB3) infection is well documented. In order to study whether the inhibition of apoptosis has an impact on CVB3 replication, the pan-caspase inhibitor Z-VAD-FMK was used. The decreased CVB3 replication is based on reduced accumulation of both viral RNA and viral proteins. These effects are due to an inhibitory influence of Z-VAD-FMK on the proteolytic activity of the CVB3 proteases 2A and 3C, which was demonstrated by using the target protein poly(A)-binding protein (PABP). The antiviral effect of the structurally different pan-caspase inhibitor Q-VD-OPH was independently of the viral protease inhibition and resulted in suppression of virus progeny production and impaired release of newly produced CVB3 from infected cells. A delayed release of cytochrome c into the cytoplasm was detected in Q-VD-OPH-treated CVB3-infected cells pointing to an involvement of caspases in the initial steps of mitochondrial membrane-permeabilization.

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Coxsackievirus B3 (CVB3), together with other enteroviruses of the picornavirus family, is associated with a wide variety of acute and chronic forms of human diseases. Using the murine model of CVB3-caused myocarditis, this pathogen can be detected not only in solid organs but also in different types of immune cells, preferentially in B lymphocytes. Therefore, these cells could represent a non-cardiac virus reservoir and may play an important role with regard to viral dissemination in the infected host. In addition, the infection of specific immune cells might modulate the severity of tissue injury and the pattern of virus-caused pathology in susceptible or resistant individuals. In the present study it could be demonstrated that CVB3 was capable to infect productively a certain percentage of murine CD19(+) B cells. In vivo studies revealed that CVB3 invaded murine CD19(+) B cells during an acute infection. Three days p. i. approximately 0.5-1.0% of these cells were productively infected. This proportion could be decreased up to 45%, if 3 days p. i. mice were intravenously treated with the pan-caspase inhibitors Z-VAD-FMK or Q-VD-OPH. These data were compared with results obtained from CVB3-infected human Raji cells.

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.