Pneumonia Virus of Mice (PVM) Infection
Laboratory hamsters, rats, and mice may be naturally infected with PVM. In an early report, interstitial pneumonia with consolidation was observed in hamsters inoculated with an infectious agent interpreted to be contaminated with PVM, but there are few details of the morphologic changes.
Conventional colonies of hamsters may be seropositive, usually in the absence of clinical disease. It is evident that PVM infections in this species normally go unrecognized as a subclinical event.Sendai Virus Infection
Sendai virus infections were once widespread among laboratory hamsters, but Sendai virus has largely disappeared from the laboratory animal scene. There are few reports of confirmed clinical disease due to Sendai virus infections in this species, although there are reports of mortality in newborn Syrian and Chinese hamsters. Young adult Syrian hamsters inoculated intranasally with Sendai virus remained subclinical, although there were changes in the upper and lower respiratory tract evident by light microscopy, and virus was recoverable from the lung during the acute stages of the infection. Hamsters seroconverted by day 7 postinoculation. Lesions included focal to segmental rhinitis progressing to necrotizing tracheitis and multifocal bronchoalveolitis. Immunohistochemistry may be used to demonstrate viral antigen in respiratory epithelial cells during the acute stages of the disease. In animals examined at 3-9 days postinoculation, lesions were very similar to those present in mice. In the reparative stages, features included hyperplasia of epithelial cells lining affected airways and peribronchial lymphocytic infiltration. In general, most lesions had resolved by 12 days postinfection.