Expression of immunoregulatory cytokines by recombinant coxsackievirus B3 variants confers protection against virus-caused myocarditis

Clinical and laboratory investigations have demonstrated the involvement of viruses and bacteria as potential causative agents in cardiovascular disea se and have specifically found coxsackievirus B3 (CVB3) to be a leading cau se. Experimental data indicate that cytokines are involved in controlling C VB3 replication. Therefore, recombinant CVB3 (CVB3rec) variants expressing the T-helper-1 (T(H)1)-specific gamma interferon (IFN-gamma) or the T(H)2-s pecific interleukin-10 (IL-10) as well as the control virus CVB3(muIL-10), which produce only biologically inactive IL-10, were established. Coding re gions of murine cytokines were cloned into the 5' end of the CVB3 wild type (CVB3wt) open reading frame and were supplied with an artificial viral 3Cp ro-specific Q-G cleavage site. Correct processing releases active cytokines , and the concentration of IFN-gamma and IL-10 was analyzed by enzyme-linke d immunosorbent assay and bioassays. In mice, CVB3wt was detectable in panc reas and heart tissue, causing massive destruction of the exocrine pancreas as well as myocardial inflammation and heart cell lysis. Most of the CVB3w t-infected mice revealed virus-associated symptoms, and some died within 28 days postinfection. In contrast, CVB3rec variants were present only in the pancreas of infected mice, causing local inflammation with subsequent heal ing. Four weeks after the first infection, surviving mice were challenged w ith the lethal CVB3H3 variant, causing casualties in the CVB3wt- and CVB3(m uIL-10)-infected groups, whereas almost none of the CVB3(IFN-gamma)- and CV B3(IL-10)-infected mice died and no pathological disorders were detectable. This study demonstrates that expression of immunoregulatory cytokines duri ng CVB3 replication simultaneously protects mice against a lethal disease a nd prevents virus-caused tissue destruction.