Latency of alpha-herpes viruses is accompanied by a chronic inflammation in human trigeminal ganglia but not in dorsal root ganglia.

The immune response to latent herpesvirus infections was compared in human trigeminal ganglia (TG) and dorsal root ganglia (DRG) of 15 dead individuals. On the basis of our previous findings, we hypothesized that T-cells would be attracted to sensory neurons latently infected with herpes simplex virus type 1 (HSV-1), but not to those harboring latent varicella zoster virus (VZV). We showed that the TG contain a positive hybridization signal for HSV-1 latency-associated transcript (LAT), whereas the DRG from the same individuals lack detectable LAT. In contrast, immunohistochemistry revealed that latent VZV protein 62 stained positive in the vast majority of all tested TG and DRG. T-cell infiltrates prominently surrounded individual neurons in the TG but not in the DRG. TaqMan polymerase chain reaction also showed higher expression of CD8 and RANTES transcripts in the TG versus DRG. Only the infiltrates in the TG, but not in the DRG, produced RANTES at the protein level. Because it has been shown that RANTES protein is produced only after T-cell receptor stimulation, we assume that T-cell infiltration is associated with antigen recognition in the TG but not in the DRG.