Role of Interferon in Lethality and Lymphoid Atrophy Induced by Coxsackievirus B3 Infection of Mice

To assess the importance of interferon (IFN) in the pathology of coxsackievirus B3 (CVB-3) infection, we evaluated both mortality rate and lymphoid involution in young adult BALB/C mice infected with lethal doses of the virus and treated either with anti-IFN antibody or with murine IFN-alpha/beta. Administration of antibody to IFN caused a profound worsening of the pathology and an increase in the mortality rate in infected animals. Treatment with murine IFN exerted a significant ameliorative effect on lethality when administered concomitantly with or soon after virus infection. The extent of this protection was correlated with the plasma levels of exogenous or endogenous IFN at 6 h postinfection, whereas no correlation with IFN titers was found later. The effects of IFN apparently were not directly mediated by antiviral effects, because at the times studied, no relation was found between IFN levels and virus titers, at least in the plasma of the infected animals. Lymphoid atrophy, assessed by measuring spleen weight, was only partially reversed by early IFN treatment. These data suggest that IFN production is critical during the early phases of infection, whereas it does not seem to play a significant protective role at later stages.