Transmission of enterotropic mouse hepatitis virus from immunocompetent and immunodeficient mice.

Mouse hepatitis virus (MHV) is the most prevalent virus that infects mice, and most MHV strains are enterotropic. Experiments were performed to elucidate the duration of enterotropic MHV-Y shedding by immunocompetent BALB/ c and C57BL/6 mice and immunocompromised B and T cell-deficient mice. Although the use of molecular diagnostics to detect MHV infection is increasing, it is unclear whether the viral RNA detected is always infectious. The ability to detect MHV-Y transmission to sentinel mice exposed directly to infected mice or to soil bedding from infected mice was compared with reverse transcriptase-polymerase chain reaction-based detection of viral RNA in the feces. The BALB/c mice developed subclinical intestinal infection, and transmitted MHV-Y for four weeks. The C57BL/6 mice also developed subclinical intestinal infection, but only transmitted virus for two weeks. The T cell-deficient mice developed severe disseminated disease by two weeks and transmitted virus for four weeks. The B cell-deficient mice developed subclinical intestinal infection and transmitted virus for longer than three months, although virus RNA was not detected in feces late in the infection. Viral RNA detected in the feces of infected mice was almost always infectious. Non-infectious RNA was detected in a few mice for several days after transmission had ceased. In addition, constant exposure of naive mice to infected mice, via the use of serial sentinels, prolonged viral transmission.