Detection of DNA and RNA virus genomes in organ systems of whole mice: patterns of mouse organ infection by polyomavirus.

A technique which detects viral DNA or RNA in situ in the organ systems of whole mice is described. Frozen thin sections from whole mice were transferred directly to nitrocellulose and hybridized to labeled viral DNA, allowing the detection of viral DNA or RNA. By this procedure, polyomavirus infection of newborn mice inoculated intranasally was followed. We found that the initial inoculum could be detected in the nasal cavity, lungs, and stomach lining after a 5-h absorption period. Primary replication of virus was observed in the nasal cavity, submaxillary gland, and lungs, followed by a systemic phase of infection in which the liver, spleen, kidney, and large colon also became infected. Viral RNA as well as DNA could also be detected as shown by infecting mice intracerebrally with vesicular stomatitis virus. Vesicular stomatitis virus-specific RNA was observed only in the brains of these mice. It is most likely that this technique can be applied to general molecular studies of mice. With this method we should be able to detect all viruses, bacteria, plasmids, and organ-specific transcripts to which a cloned probe exists.