Detection of human herpes virus 6B in patients with mesial temporal lobe epilepsy in West China and the possible association with elevated NF-κB expression.

Background: There has been a long-standing suspicion that an association exists between mesial temporal lobe epilepsy (MTLE) and the herpes virus. Evidence for HHV-6B involvement has been reported. However, no investigation has been performed in China.

Methods: We used nested PCR and immunohistochemistry to detect viral DNA of human herpes virus (HHV)-6B, HHV-6A, herpes simplex virus (HSV)-1 and HSV-2 in resected brain tissues from patients with MTLE and control. A principal transcription factor, NF-κB, that is associated with the inflammatory response was also investigated by real-time PCR, western blotting and immunohistochemistry.

Results: HHV-6B DNA was detected in hippocampal samples from 9 out of 32 (28.1%) patients with MTLE and in 1 of 12 (8.3%) control samples. Immunoreactivity for HHV-6B was consistently present in MTLE patients positive for HHV-6 detected by PCR. Significant staining for HHV-6B antigen was distributed mainly around or in the nucleus of cells that morphologically resembled astrocytes and microglia. HHV-6B positivity was related to febrile convulsion history of patients with MTLE. The expression of NF-κB was up-regulated and distributed in the nucleus of glial cells in MTLE patients positive for HHV-6B.

Conclusion: This study was first to find HHV-6B in MTLE patients from West China and demonstrate a possible association between HHV-6B positivity and activation of NF-κB. The detailed role of HHV-6B and its association with NF-κB in the development of chronic MTLE requires further investigation.