An international group of HHV-6 researchers have come together to review and call attention to the important classification of HHV-6A and HHV-6B as separate viruses.  In 2012, the International Committee on Taxonomy of Viruses (ICTV) classified HHV-6A and HHV-6B as separate viruses. This review outlines several of the documented epidemiological, biological, and immunological distinctions between HHV-6A and HHV- 6B, which support the ICTV classification. For clarity in biological and clinical distinctions between HHV-6A and HHV-6B moving forward, the group urges scientists and physicians, where possible, to differentiate carefully between HHV-6A and HHV-6B in all future publications.  READ MORE

Chimerix, Inc., a biopharmaceutical company developing novel antivirals in areas of high unmet medical need, announced last month that their phase 3 trial of Brincidofovir (formerly CMX001) will include a secondary endpoint to determine the drug's effectiveness in limiting the effects of HHV-6 infection among stem cell transplant patients.  While the primary endpoint of the "SUPPRESS" trial is to determine efficacy in the treatment of CMV, this marks the largest multi-center prospective placebo-controlled trial to ever be conducted in HHV-6 infection.  In addition to collecting fluid specimens, the group will also collect clinical data that will be used in analysis.  One of the key pieces of clinical data that will be analyzed in conjunction with HHV-6 is the daily assessment of mental status, which has been shown previously in prospective studies to be highly correlated with reactivation of HHV-6.  READ MORE

A role for HHV-6A/B has been proposed in several autoimmune disorders, including multiple sclerosis (MS), autoimmune connective tissue diseases, and Hashimoto's thyroiditis.  In an article published this month, researchers from Italy discuss the potential mechanisms by which HHV-6A/B may contribute to the development of autoimmune diseases such as those listed above.  READ MORE

Several laboratories worldwide have released articles this month that contribute to a deeper molecular, immunological, and/or pathological understanding of HHV-6A and HHV-6B.  Here are a few key publications from the bench that you don't want to miss: 

Human herpesvirus 6 (HHV-6) alters E2F1/Rb pathways and utilizes the E2F1 transcription factor to express viral genes.  [From the laboratory of Dr. Niza Frenkel, Tel Aviv University, Israel]

MHC class I molecules are incorporated into human herpesvirus-6 viral particles and released into the extracellular environment.     AND    Human herpesvirus-6A gQ1 and gQ2 are critical for human CD46 usage.  [From the laboratory of Dr. Yasuko Mori, Kobe University Graduate School of Medicine, Japan]

Human herpesvirus-6B protein U19 contains a p53 BOX I homology motif for HDM2 binding and p53 stabilization.  [From the laboratory of Dr. Per Hollsberg, Aarhus University, Denmark]

Development of virus-specific CD4+ and CD8+ regulatory T cells induced by human herpesvirus-6infection.  [From the Laboratory of Dr. Kun Yao, Nanjing Medical University, China]

Immunomodulation and immunosuppression by human herpesvirus 6A and 6B.  [From the laboratory of Dr. Paolo Lusso, NIH/NIAID, USA]

A group from Paris, France has reported a case of fulminant HHV-6 myocarditis in a 28-year-old immunocompetent patient.  As the authors note in their report, “HHV6 is one of the most frequent viral causes of myocarditis, found in up to 23% to 36% of cases in series with endomyocardial biopsies, [and] is associated frequently with acute and chronic heart failure…As opposed to other viral causes of myocarditis, HHV6 infection, although rarely symptomatic in the early stage, is likely to have a worse prognosis.”  HHV-6 myocarditis can be challenging to definitively diagnose in the clinical setting. However, the group suggests that, together with newly available multiplex PCR microarray assays, cardiac magnetic resonance (CMR) may be an important tool for the timely diagnosis and clinical management of this condition.  READ MORE