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.
HHV-6 reactivation associated with fever after autologous transplantation
Half of autologous hematopoietic cell transplant patients with HHV-6 reactivation exhibit fever plus a collection of symptoms that include diarrhea, rash and pneumonia.
Review of HHV-6 in Liver Transplantation
HHV-6 infections in the liver transplant patients can’t be diagnosed in the blood. Ganciclovir prophylaxis for CMV cuts the rate of HHV-6 reactivation from 39% to 11%.
New study details devastating impact of HHV-6 encephalitis
Investigators in Japan studied 145 patients who developed HHV-6 encephalitis. At 100 days after transplantation, the overall survival rate was just 58.3%, compared with 80.5% for patients who did not develop encephalitis. High-dose antiviral therapy was shown to mitigate high mortality rates in these patients.
HHV-6 reactivation associated with longer hospital stays, more readmissions in Memorial Sloan Kettering Trial
T-cell depleted stem cell transplant patients at Memorial Sloan Kettering Cancer Center with HHV-6 viremia, CMV viremia, or 2 or more viremias experienced longer hospital stays and were readmitted more often. HHV-6 was the most commonly reactivated virus, with 61% of patients affected patients .
HHV-6 reactivation, monocytes and B cells are unusually elevated in cord blood transplant patients
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.
Low sodium levels associated with HHV-6 encephalitis
Retrospective analysis of transplant patients revealed that low serum sodium levels are associated with HHV-6 encephalitis, but not HHV-6 myelitis. Low sodium is a possible marker for HHV-6 encephalitis post-transplantation.
HHV-6 reactivation and poor CD4+ cell reconstitution predict pediatric acute GVHD
Over a dozen studies have now found HHV-6 to predict aGVHD, but this is the first to correlate viral reactivation with poor CD4+ cell immune reconstitution.
Opinion: call for ciHHV6 screening in transplantion
Two physicians from Texas propose that ciHHV6 status of donors and recipients be determined before solid organ transplantion, using a single pre-transplant qPCR test on whole blood, and that patients with ciHHV-6 or ciHHV-6 donors be carefully monitored for signs of active HHV-6 infection.
Multiple viral infections and HHV-6B increase risk of mortality in HSCT
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.
HHV-6 induced amnesia after rituximab therapy for autoimmune disease
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.
Immune reconstitution dramatically alters chance of survival in stem cell transplant patients with HHV-6 reactivation
Only 11% of HHV-6 reactivated patients with poor immune reconstitution survived compared to 63% in patients with higher levels of T cells (or over 200 CD3+ lymphocytes per microliter).
HHV-6 found to cause 35% of CNS infections in allo-HSCT transplantation
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.
New data on HHV-6B levels in CD134+ CD4+ cells
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.
Does CD134 upregulation explain why HHV-6 reactivates preferentially in DRESS/ DIHS?
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.