Antiviral action of trehalose dimycolate against EMC virus: role of macrophages and interferon α/β

Preventive treatment of mice with trehalose 6,6′ dimycolate (TDM), an immunomodulator of bacterial origin, enhances their resistance to encephalomyocarditis (EMC) virus infection. The protective effect of TDM is totally abolished by the injection of silica particles in mice, demonstrating the role of macrophages in the antiviral action of TDM. In vitro, peritoneal macrophages from mice treated with TDM (TDM-PM) exhibit an intrinsic antiviral activity against EMC virus, while resident peritoneal macrophages (RES-PM) are permissive to this virus. Greater amounts of interferon are detected in supernatants of cultures of TDM-PM than of RES-PM. Neutralization of interferon (IFN) by addition in vitro of anti-IFN α/β serum markedly reduces the antiviral activity of TDM-PM. These results indicate that interferon α/β is involved in the intrinsic anti-EMC virus activity of peritoneal macrophages from mice treated with TDM.