Patterns of gene expression and sites of latency in human nerve ganglia are different for varicella-zoster and herpes simplex viruses.

The cellular localization and viral transcription patterns of acute and latent varicella-zoster virus (VZV) infections of human sensory nerve ganglia were studied by in situ hybridization and compared with those of latent herpes simplex virus (HSV) infection. Trigeminal and dorsal root ganglia obtained at autopsy were hybridized with 35S-labeled single-stranded RNA probes homologous to VZV or HSV fragments. We have reported that HSV persists in human sensory neurons and expresses only one family of transcripts that overlap extensively with, but are opposite in polarity to, the mRNA encoding the immediate early protein termed infected cell protein 0 (ICP0). In the present study we find that latent VZV infection involves nonneuronal cells, and multiple, but not all, VZV genes are transcribed. In contrast, during varicella both neuronal and nonneuronal cells are infected, with all regions of the VZV genome analyzed being expressed. Thus, the patterns of gene expression and cellular locations of VZV and HSV infections of human ganglia differ. The differences may underlie clinical features that distinguish these infections.