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Does HHV-6 encephalitis trigger mitochondrial disease in children with POLG mitochondrial disorders? Two cases of fatal Alpers-Huttenlocher syndrome

A team of clinicians and researchers from the University of Michigan Medical School and Washington University in St. Louis has detailed two cases of fatal HHV-6 encephalitis in children with underlying POLG mitochondrial disorders.  In the report, published this month in the journal Pediatric Neurology, the group describes a marked disease progression in two previously healthy young boys with HHV-6-associated encephalitis that developed into a progressive, and ultimately fatal, encephalopathy with refractory movement disorder concurrent with acquisition of acute HHV-6 infection.  READ MORE

HHV-6A protein identified in spinal fluid of patients with MS: a case of molecular mimicry?

Approximately 20% of MS patients have HHV-6 specific oligoclonal bands in their spinal fluid (CSF), indicating a humoral immune response or IgG reaction against HHV-6. However, it was previously unknown which viral protein was inducing this antibody response, and furthermore whether the protein was derived from HHV-6A or HHV-6B.  In a new article, a group from Spain has identified the protein: HHV-6A major capsid protein, which is produced during viral replication of HHV-6A.  READ MORE

Risk of HHV-6 encephalopathy linked to a specific Class 1 HLA-B allele

A group from Japan has conducted a retrospective study of 130 patients who underwent stem cell transplantation in an attempt to identify a risk factor for the development of encephalopathy. Although HLA mismatch and unrelated donor status were strongly associated with HHV-6 reactivation (odds ratio of 5.6 and 4.5, respectively) these factors were not associated with HHV-6 encephalopathy, a condition that can often result in permanent neurologic disability and/or death of the patient.  Interestingly, however, the investigators found a remarkably increased level of risk (odds ratio of 31.1) for the development of encephalopathy when transplant occurred with HLA Class I allele HLA-B*40:06 in particular.  HLA class I alleles have been associated with several autoimmune diseases as well as viral infections.  READ MORE

HHV-6B: an underappreciated cause of hepatitis in stem cell transplant patients

Although HHV-6 infection in solid organ transplant patients has been well documented, the role of HHV-6 in stem cell transplant cases has not been similarly studied.  A recent article published in Transplant Infectious Disease describes a case of acute hepatitis in a hematopoietic cell transplant (HCT) recipient likely caused by HHV-6B, and reviews the current literature on HHV-6B associated hepatitis.  The article was written by a team from the University of Washington and Fred Hutchinson Cancer Research Center, and concludes that HHV-6-associated hepatitis may be an underappreciated entity in HCT patients. Currently, HHV-6 testing is not part of the initial screening protocol for suspected hepatitis at most HCT centers. READ MORE