Effect of inapparent murine hepatitis virus infections on macrophages and host resistance

Inapparent infections of mice with murine hepatitis virus (MHV) altered host resistance to experimental infection with a second virus, encephalomyocarditis virus (EMC), reduced the protective effects of exogenously administered interferon against EMC infections, and it altered macrophage ectoenzyme phenotypes in two macrophage populations. Resident peritoneal macrophages from mice experimentally infected with one of two strains of MHV also demonstrated altered ectoenzyme phenotypes. These data demonstrate that inapparent infections with MHV alter several host resistance and macrophage parameters and directly demonstrate that effects of inapparent MHV infection on macrophage parameters can be reproduced experimentally.