Susceptibility of laboratory mice to intranasal and contact infection with coronaviruses of other species.

The susceptibility of laboratory mice to intranasal and contact infection with mouse hepatitis virus (MHV)-related coronaviruses was tested in infant CD1 mice. One day old mouse pups were inoculated intranasally with respiratory MHV-S, enteric MHV-Y, rat sialodacryoadenitis virus (SDAV), human coronavirus OC43 (HCV-OC43) or bovine coronavirus (BCV). Twenty-four hours later, they were placed in direct contact with age matched sham inoculated pups. Indices of infection in virus inoculated mice included lesions by histopathology and viral antigen by immunoperoxidase histochemistry in brain, lung, liver and intestine at 3 days after inoculation. Indices of infection in contact mice included mortality or seroconversion by 21 days after exposure. Infant mice were susceptible to infection with all five viruses. Transmission by direct contact exposure occurred with MHV and SDAV, but not HCV or BCV. Furthermore, adult mice were not susceptible to infection with HCV. Tissue distribution of lesions and antigen varied markedly among viruses, indicating that they do not induce the same disease as MHV. This study demonstrates that although these coronaviruses are antigenically closely related, they are biologically different viruses and disease patterns in susceptible infant mice can be used to differentiate viruses.