MORTALITY IN MICE INFECTED WITH AN AMYOCARDITIC COXSACKIEVIRUS AND GIVEN A SUBACUTE DOSE OF MERCURIC CHLORIDE

Abstract

An amyocarditic strain of coxsackievirus B3 (CVB3/0) induces heart damage when inoculated into selenium (Se)-deficient mice. Mercury (Hg), an Se antagonist, is known to aggravate viral infections. The experiments reported here assessed the effect of prior Hg treatment in mice subsequently inoculated with an amyocarditic strain of coxsackievirus. A pilot study showed that under our conditions the maximum tolerated dose of HgCl₂ in uninfected mice was 6 mg HgCl₂/kg body weight. In the main study, doses of 0, 3 or 6 mg HgCl₂/kg body weight were administered intraperitoneally (ip) to 7-wk-old male mice fed a standard chow diet. Two hours later, half the mice were inoculated ip with CVB3/0. Ten days postinoculation, no mortality was observed in mice given only virus. In mice not given virus, 10% injected with 6 mg HgCl₂/kg body weight died. On the other hand, 64% of the mice given both virus and 6 mg HgCl₂/kg body weight died. Fifteen percent of the hearts from virus-infected mice given 3 mg HgCl₂/kg body weight and 33% of the hearts from virus-infected mice given 6 mg HgCl₂/kg body weight exhibited a higher incidence of lesions than hearts from mice-given virus alone. Moreover, viral heart titers were elevated in infected mice injected with 6 mg HgCl₂/kg body weight compared to infected mice receiving no Hg. Thus, an amyocarditic coxsackievirus given to mice after a nonlethal subacute dose of Hg results in mortality, increased incidence of heart lesions, and elevated viral heart titers. These results demonstrate the important role of toxic elements in determining the severity of viral infections.