Presence of human herpes virus 6 DNA exclusively in temporal lobe epilepsy brain tissue of patients with history of encephalitis.

Temporal lobe epilepsy (TLE) is frequently associated with mesial temporal sclerosis (MTS). Many etiologic aspects of TLE are still unresolved. Here, we aimed to analyze the presence of human herpes virus 6 (HHV-6) DNA in distinct TLE pathologies. Nested polymerase chain reaction (PCR) in surgical tissue from 38 pharmaco-resistant TLE patients and 10 autopsy controls revealed HHV-6 DNA in 55.6% of the TLE patients with a history of encephalitis, involving MTS and gliotic hippocampi without substantial neurodegeneration, but not in lesion-associated TLE or nonlesional MTS with or without a history of complex febrile seizures (CFS). HHV-6 protein was present in only one patient's tissue. Our data argue against HHV-6 as a major local pathogenetic factor in MTS hippocampi after CFS. The high detection rate of HHV-6 DNA suggests a potential pathogenetic role of HHV-6 in TLE patients with a history of encephalitis.