Previous reports (Fotheringham 2007) have found higher levels of HHV-6B DNA and antigens in brain tissue resected to treat mesial temporal lobe epilepsy (MTLE), but not in control tissue, as summarized in Komaroff 2020. A new paper from several medical centers in China examined surgically resected neocortical or hippocampal specimens from 49 patients with MTLE and 19 people with serious brain trauma or a vascular event who had tissue resected from the same parts of the brain.
The team found:
- Significantly more mesial temporal lobe epilepsy (MTLE) patients (39%) had HHV-6B DNA in brain tissue compared to controls (5%, P<0.001);
- Specimens in which viral DNA was present were also positive for viral antigens;
- There was an upregulation of IL-1a, IL-2 and IL-7 mRNA in MTLE brain tissues, perhaps more so in tissue expressing HHV-6B early antigens;
- HHV-6B early antigen (P41) was found in 3 MTLE patients (6%), late antigen (gp116/54/64) in 5 patients (10%), latent antigen (U94) in 8 patients (16%), and multiple antigen (early and late or/and latent) 9 patients (18%), whereas none of these HHV-6B proteins were found in control brain tissue;
- As might be expected, DNA load was higher specimens with early, late or multiple antibodies than in the group with latent antigen (Figure 1),.
The investigators suggest that the increased production of several cytokines, particularly in patients with reactivated HHV-6B infection, may contribute to the pathogenesis of seizures in those cases of MTLE that are associated with HHV-6B. The authors note that while viral DNA is difficult to detect in the cerebrospinal fluid (CSF), up-regulation of IL-1a and IL-7 in the CSF may be useful as an indirect marker of HHV-6B infection.
Read the full study here: Wang 2022