Natural antiviral activity of mouse macrophages against encephalomyocarditis virus.

Resident mouse peritoneal cells (PC) express a significant antiviral activity against encephalomyocarditis virus (EMCV) in vitro, as judged by decreased virus yield from infected mouse embryo fibroblasts (MEF). This natural antiviral activity of PC was not due either to enhanced lysis of virus-infected cells, as these were protected from lysis rather than destructed by PC, or to interferon (IFN) production, as no direct correlation between IFN and anti-EMCV activity was found. Among PC, macrophages (M phi) appear to be responsible for the anti-EMCV activity, which was indeed attributable to a Thy 1.2-negative, adherent mononuclear cell. Moreover, M phi-defective C3H/HeJ mice showed a significant impairment of anti-EMCV activity, whereas M phi of mice defective for natural killer (NK) activity (bg/bg, SJL/J) or for mature T cells (nu/nu) possessed an intact antiviral capacity.