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HHV-6B reactivates first, proceeds to end organ disease faster in transplant patients

In All, Transplant Complications by Kristin Loomis

Investigators at Fred Hutch Cancer Research Center found that HHV-6B is the first DNA virus to reactivate at a median of 3 weeks, compared to CMV, EBV and Adenovirus at 5-6 weeks. HHV-6B also peaked rapidly, unlike other DNA viruses that took 3-6 weeks to reach peak viral load. HHV-6B reactivation resulted in increased mortality after 100 days.

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HHV-6 reactivation, monocytes and B cells are unusually elevated in cord blood transplant patients

In All, Transplant Complications by Kristin Loomis

CD8+ T cells recover but CD4+ T cells remain low

Investigators in France discovered that monocytes and B lymphocytes recover quickly and become abnormally elevated by day 75 in cord blood patients, while they remain below normal or normal in stem cell patients. Although CD8 T cells recover, CD4+ T cells remain below normal levels for six months in both groups.

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Multiple viral infections and HHV-6B increase risk of mortality in HSCT

In All, Transplant Complications by Kristin Loomis

A retrospective study of allogeneic hematopoietic stem cell transplant patients at University of Washington found that reactivation of several double stranded DNA viruses significantly increased the risk of overall mortality, as did an increased quantitative burden of viral exposure. HHV-6B conferred a significantly increased risk for overall mortality.

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HHV-6 induced amnesia after rituximab therapy for autoimmune disease

In All, CNS Dysfunction, Encephalitis & Encephalopathy, Transplant Complications by Kristin Loomis

A young woman on rituximab and two other immunomodulatory agents for the treatment of dermatomyositis developed encephalitis with severe anterograde amnesia. As the use of biologic treatments for refractory autoimmune disease has been increasing, physicians are advised to consider HHV-6 and offer prompt antiviral therapy to limit irreversible morbidity.

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HHV-6 found to cause 35% of CNS infections in allo-HSCT transplantation

In All, CNS Disease, Transplant Complications by Kristin Loomis

A retrospective analysis out of the Tokyo Metropolitan Cancer and Infectious Diseases Center reviewed 353 consecutive adult allogeneic hematopoietic stem cell transplant (allo-HSCT) cases and identified 17 cases of CNS infection post-transplant. As determined by PCR on cerebrospinal fluid, HHV-6 was found to be the causative agent in 6 cases, or 1.7% of all transplants.

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New data on HHV-6B levels in CD134+ CD4+ cells

In All, Transplant Complications by Kristin Loomis

A group from the University of Minnesota studied the T cells of umbilical cord blood transplant patients and found that CD4+ T lymphocytes co-expressing CD134 contained more than twice the level of HHV-6B than cells without CD134 expression. Surprisingly, almost 70% of the CD134 negative cells contained HHV-6.

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Does CD134 upregulation explain why HHV-6 reactivates preferentially in DRESS/ DIHS?

In All, Drug Hypersensitivity, Latest Scientific News, Skin Conditions, Transplant Complications by Kristin Loomis

It has long been a mystery why HHV-6 is preferentially reactivated in drug reaction with eosinophilia and systemic symptoms (DRESS), also known as drug induced hypersensitivity syndrome (DIHS). HHV-6 reactivation occurs in over 60% of severe cases and is part of the definition of DIHS in Japan. Investigators in Japan suspect that the explanation may lie with the CD134 receptor on activated CD4 cells.