Interview with Tetsushi Yoshikawa: Treating HHV-6B seizures

Tetsushi Yoshikawa and Yoshiki Kawamura just published an important study linking HHV-6B in brain tissues to sclerosis in mesial temporal lobe epilepsy (MTLE). We asked him about this future plans and whether he plans to treat these patients. Read a  summary of their study here.

Q: How would you describe the importance of your study?

A: As MTLE is difficult to control by anti-epileptic drugs, the present data may be the first step for developing new a treatment strategy.

Q: Should antiviral therapy be considered for infants with HHV-6B induced complex seizures?

A: A New paper from THE NIAID Collaborative Antiviral Study Group (Kimberlin 2015) suggests that 6 months of ganciclovir (GCV) treatment is better than 6 weeks treatment, for children with congenital CMV. Recently, we administered GCV for 6 months for two cases of congenital CMV patients without remarkable side effects. Therefore, I think that GCV treatment is acceptable for HHV-6 encephalitis treatment for infants with a primary HHV-6B infection, even though we have no data for its effectiveness. However, further studies are needed to determine whether GCV should be administered in patients with HHV-6B associated complex seizures or not.

Q: How would you design a clinical trial for treatment?

A: It is difficult to differentiate between complex type of febrile seizure and HHV-6 encephalitis at the time of disease onset. Therefore, we are planning a randomized study for GCV treatment in patients with the complex type of febrile seizure (including few cases with encephalitis), who are rapidly diagnosed by HHV-6 LAMP method in our clinic at the time of the seizure.

Q: How long do you plan to follow the children who are treated for HHV-6B infection?

A: I think that children with HHV-6B encephalitis could be followed for long time to determine whether the encephalitis is associated with MTLE or not. But, it would be difficult to follow the children with HHV-6B associated complex seizures for long period after the first seizure.

Q: Since HHV-6 DNA can induce neuroinflammation in the absence of replication (Horvat 2014, Clark 2013), should anti-inflammatories be considered for these patients as well? 

A: If the virus replication does not occur in brain tissue, antiviral drugs might be ineffective. However, I think that anti-inflammatories might be effective for prevention of neurological damages caused by latently infected virus.

Q: Do you believe that children who succumb to HHV-6B induced epilepsy might have a defect in cellular immune response, mineral deficiency or genetic abnormality that prevents them from keeping this virus under control?

A: I think that some genetic factors may be involved in the disease pathogenesis. I have no idea in terms of a defect of cellular immune response and mineral deficiency.

Q: How will the results of your study will this affect your current protocols for clinical testing? 

A: I think that further study is required to elucidate role of HHV-6 in pathogenesis of MTLE. We are now planning new strategies to clarify the host factors that are affected by HHV-6 reactivation in MTLE patients.

Q: What additional studies must be done to convince the neurologists that HHV-6B plays a role in MTLE?

A: Whole RNA-sequence analysis may allow us to clarify the difference of host gene expressions between normal and HHV-6B infected patient’s brain tissues.

To read about their study published in Journal Infectious Disease, click here.