Detection of murine cytomegalovirus immediate early 1 transcripts in the spleens of latently infected mice.

The spleens of mice latently infected with murine cytomegalovirus were examined by reverse transcription followed by the polymerase chain reaction to assay for transcriptional activity of the viral immediate early 1 gene. Transcripts were detected in 6 of 8 animals at a level between 50 and 500 copies in 200 ng of total cellular RNA. This level appears to be roughly 10-fold higher than that of viral genome even though viral DNA is more readily detectable. These data suggest that a significant fraction of latent murine cytomegalovirus is transcriptionally active in the spleen, which may be indicative of an abortive infection or possibly low-level persistence or a transient reactivation.