Lethal enteritis in infant mice caused by mouse hepatitis virus

Mouse hepatitis virus (MHV) has been described as a common cause of enteric infection in baby mice. It is highly contagious and highly lethal when initially introduced into a colony. In epizootics such as the one described, there is no maternal antibody protection of the newborn mouse. Diagnosis and understanding of this disease have been obscured by 2 continuing difficulties. First, the description of the lethal intestinal virus of infant mice (LIVIM) (see Biggers D.C. et al. Am. J. Pathol., 1964, 45, 413) as a distinct syndrome had led erroneously to the assumption that a distinct but unknown etiologic agent must be responsible, although at one time, LIVIM infection was also thought to be the product of 2 interacting viruses: the epizootic diarrhea of infant mice virus (EDIM), and MHV. Second, there has been too little appreciation of the very different organ tropisms of MHV. For, after infection of adult mice, a necrotizing hepatitis may predominate, while in suckling mice, death may result from encephalitis or enteritis. In view of this direct etiologic association of MHV with lethal enteritis of newborn mice (in the absence of other detectable viral agents), it now seems that the term LIVIM should be discarded. Moreover, if the extraordinary contagiousness of MHV is appreciated when this kind of enteritis is seen, eradication procedures may be adjusted accordingly.