Etiology: Pneumonia Virus of Mice (PVM) is a pneumovirus of the family Paramyxoviridae. It is a single stranded enveloped RNA virus.
Incidence: The incidence of infection is rare.
Transmission: Direct contact is the primary means of transmission. The virus is not stable in the environment, losing 99% infectivity at room temperature in an hour.
Clinical signs: PVM causes a silent infection in immunocompetent mice and is not highly contagious as infections are slow to spread in conventional colonies. Immunocompromised mice are persistently infected, develop progressive pneumonia, can lose weight and develop dyspnea.
Pathology: Lesions in immunocompetent mice are rare. In nude mice, progressive bronchointerstitial pneumonia develops. Desquamation and hyperplasia of bronchiolar epithelium occurs and is accompanied by alveolar consolidation with cellular debris and edema.
Diagnosis: Serologic assays using MFI or IFA are the primary means of diagnosing infection. In immunodeficient mice, an etiologic diagnosis is accomplished by use of a PVM-specific PCR assay or virus isolation on BHK-21 cells.