DISTRIBUTION OF K-PAPOVAVIRUS IN INFECTED NEWBORN MICE

Newborn mice were inoculated orally with 100 LD(50) of K-papovavirus a nd the distribution of virus in fatally infected animals was studied b y in-situ nucleic acid hybridization methods and immunoperoxidase stai ning for K virus capsid (V) antigen. Histopathologically, K virus prod uced extensive involvement of pulmonary endothelial cells, resulting i n interstitial pneumonia, and widespread involvement of other endothel ial cell populations throughout the systemic circulation. Endothelial cells in lungs, kidneys and other organs exhibited both specific hybri dization for K virus nucleic acids and positive staining for K virus V antigen, indicative of productive infection. Scattered, apparently ex travascular cells within brain parenchyma also exhibited both specific hybridization and immunohistological staining for K virus V antigen. In contrast, specific hybridization for K virus nucleic acids, in the absence of immunohistochemical labelling of K virus V antigen, suggest ing transcription of viral DNA without expression of viral proteins, w as detected in renal tubular epithelial cells and nonvascular, apparen tly lymphoid cells within the spleen and lymph nodes. The present stud y confirms the predominantly endotheliotropic nature of K virus infect ion in newborn mice and also demonstrates that the virus invades renal epithelial, lymphoid and possibly glial cells during primary infectio n.