Host and viral gene expression in murine gammaherpesvirus 68 infected primary peritoneal mouse macrophages harvested 16 hours post-infection in vivo

Among virally infected macrophages, only rare (0.25%) cells had lytic cycle gene expression, characterized by detection of multiple lytic cycle RNAs. In contrast, ~50% of virally-infected macrophages were characterized by expression of ORF75A, ORF75B and/or ORF75C, in the absence of other detectable viral RNAs. Selective transcription of the ORF75 locus is a unique and unanticipated viral transcription signature that is not predicted based on current models of either lytic replication or latent infection.

These studies, in combination with related experimental approaches, indicate that MHV68 efficiently infects macrophages, with the majority of cells characterized by an atypical state of restricted viral transcription, with only rare cells undergoing lytic replication at early times post-infection.