Detection of Herpesviridae in postmortem multiple sclerosis brain tissue and controls by polymerase chain reaction

Objective: To test for the presence of herpesviruses in postmortem brain samples from multiple sclerosis patients and controls using polymerase chain reaction. Background: Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, and human herpesvirus-6 are common viruses capable of persistence and latency. All have been detected in the CNS. Methods: Active and inactive plaque tissue, unaffected white matter (WM) and gray matter (GM) from MS cases, and WM and GM controls (Alzheimer's disease, Parkinson's disease and non-neurological disease) were screened for the herpesvirus by PCR. Results: (1) 37% of the MS cases were positive for herpes simplex virus (HSV). Twenty-eight percent of controls cases were positive for HSV. Forty-one percent of active plaques were positive for HSV in contrast to only 20% of inactive plaques (Sanders ef al, 1996). (2) 57% of the MS cases and 43% of the control cases were positive for HHV-6. Thirty-two percent of the active plaques contained HHV-6 compared to 17% of inactive plaques. (3) 43% of the MS cases and 32% of the control cases were positive for VZV. Fourteen percent of the active plaques and 10% ofthe inactive plaques were positive for VZV. (4) 27% of MS cases and 38% of control cases were positive for EBV. Five percent of the active plaques were positive for EBV and 10% ofthe inactive plaques were positive. (5) 16% of the MS cases and 22% ofthe controls were positive for CMV. Nine percent ofthe active plaques and 10% ofthe inactive plaques were positive. We also compared MS WM and GM with controls and found no significant difference. Conclusions: HSV, HHV-6, and VZV were present in a greater frequency of MS cases compared to controls; however, no statistical differences were noted. The presence of herpesvirus in all tissue makes an etiologic association to MS uncertain. Cellular localization of virus and its relationship to pathology and latency may reveal an association.