Coxsackie B virus infection in idiopathic dilated cardiomyopathy: clinical and pharmacological implications

In vitro screening of traditionally used medicinal plants in China against Enteroviruses

AIM: To search for new antiviral agents from traditional Chinese medicine, specifically anti-enterovirosuses agents.

METHODS: The aqueous extracts (AE) of more than 100 traditionally used medicinal plants in China were evaluated for their In vitro anti-Coxsackie virus B3 activities with a MTT-based colorimetric assay.

RESULTS: The test for AE of 16 plants exhibited anti-Coxsackie virus B3 activities at different magnitudes of potency. They can inhibit three steps (inactivation, adsorption and replication) during the infection. Among the 16 plants, Sargentodoxa cuneata (Oliv.) Rehd. et Wils., Sophora tonkinensis Gapnep., Paeonia veitchii Lynch, Spatholobus suberectus Dunn. and Cyrtomium fortunei J. sm. also have activity against other enterovirus, including Coxsackie virus B5, Polio virus I, Echo virus 9 and Echo virus 29. Cell cytotoxic assay demonstrated that all tested AE had CC₅₀ values higher than their EC₅₀ values.

CONCLUSION: The sixteen traditionally used medicinal plants in China possessed antiviral activity, and some of them merit further investigations.

Generation and analysis of an RNA vaccine that protects against coxsackievirus B3 challenge

Coxsackievirus B3 (CVB3) is an important human pathogen that causes substantial morbidity and mortality but, to date, no vaccine is available. We have generated an RNA-based vaccine against CVB3 and have evaluated it in the murine model of infection. The vaccine was designed to allow production of the viral polyprotein, which should be cleaved to generate most of the viral proteins in their mature form; but infectious virus should not be produced. In vitro translation studies indicated that the mutant polyprotein was efficiently translated and was processed as expected. The mutant RNA was not amplified in transfected cells, and infectious particles were not produced. Furthermore, the candidate RNA vaccine appeared safe in vivo, causing no detectable pathology following injection. Finally, despite failing to induce detectable neutralizing antibodies, the candidate RNA vaccine conferred substantial protection against virus challenge, either with an attenuated recombinant CVB3, or with the highly pathogenic wt virus.

Synergistic drug combinations against the in vitro replication of Coxsackie B1 virus

The existence of synergistic drug combinations against the in vitro replication of poliovirus type 1 (Mahoney) (PV-1) had been established in our previous work. The objective of the present study was to test the combined effects of the different drugs against another representative of the enterovirus genus, i.e. Coxsackievirus B1 (CBV-1). Dual combinations of enviroxime, disoxaril, arildone, PTU-23, HBB and S-7 were evaluated. The susceptibility of CBV-1 to the individual effects of the inhibitors was compared to that of PV-1. CBV-1 was more sensitive to enviroxime, S-7, PTU-23 and HBB and less sensitive to the effects of disoxaril and arildone. The effect of most dual drug combinations tested against CBV-1 replication was additive or synergistic. Enviroxime and S-7, enviroxime and PTU-23, disoxaril and HBB, disoxaril and PTU-23, arildone and HBB, arildone and PTU-23, S-7 and HBB revealed a strong synergistic effect. Synergy against CBV-1 replication was stronger as compared to that noted for the same drug combinations against PV-1 replication.

Mycophenolate mofetil inhibits the development of Coxsackie B3-virus-induced myocarditis in mice

Background

Viral replication as well as an immunopathological component are assumed to be involved in the development of coxsackie B virus (CBV)-induced myocarditis. We observed that mycophenolic acid (MPA), the active metabolite of the immunosuppressive agent mycophenolate mofetil (MMF), inhibits coxsackie B3 virus (CBV3) replication in primary Human myocardial fibroblasts. We therefore studied whether MMF, which is thus endowed with a direct antiviral as well as immunosuppressive effect, may prevent CBV-induced myocarditis in a murine model.

Results

Four week old C3H-mice were infected with CBV3 and received twice daily, for 7 consecutive days (from one day before to 5 days post-virus inoculation) treatment with MMF via oral gavage. Treatment with MMF resulted in a significant reduction in the development of CBV-induced myocarditis as assessed by morphometric analysis, i.e. 78% reduction when MMF was administered at 300 mg/kg/day (p < 0.001), 65% reduction at 200 mg/kg/day (p < 0.001), and 52% reduction at 100 mg/kg/day (p = 0.001). The beneficial effect could not be ascribed to inhibition of viral replication since titers of infectious virus and viral RNA in heart tissue were increased in MMF-treated animals as compared to untreated animals.

Conclusion

The immunosuppressive agent MMF results in an important reduction of CBV3-induced myocarditis in a murine model.