Although depleting naïve T cells has been successful in preventing acute graft vs host disease in several studies, investigators from Spain reported an unexpectedly high incidence of HHV-6 encephalitis in a cohort of haploidentical transplant patients.
HHV-6 reactivation associated with unexplained fever and biliary atresia in pediatric liver transplant patients
A Japanese study found that unexplained fever and biliary atresia are associated with HHV-6B infection in pediatric transplant patients. 100% of seronegative infants developed a primary infection.
Meta-analysis shows strong association of HHV-6B reactivation and subsequent aGVHD
A new meta-analysis published in Biology of Blood and Marrow Transplantation shows that transplant patients who reactivate with HHV-6 are 2-3 times more likely to develop acute GVHD.
Cross-sectional analysis of CD8 T cell immunity to HHV-6B identifies new targets for adoptive T cell therapy
German investigators conducted a broad scale analysis of CD8 T cell responses to HHV-6B, identifying novel epitopes with potential for immunotherapy or vaccines. The strongest responses were directed against an epitope from IE-2.
Cord blood transplant patients with early HHV-6 reactivation have a 4x greater relapse rate
Investigators at the University of Minnesota found that cord blood transplant cancer patients with HHV-6B reactivation in the first 28 days are almost 4x more likely to relapse in the first two years compared to those with no early reactivation.
Late HHV-6B reactivation an independent risk factor for mortality in pediatric HCT
Late HHV-6B reactivation after 60 days was an independent risk factor for mortality in Japanese pediatric hematopoietic cell transplant recipients. Older children and those with hematologic malignancy were 10x more likely to develop late reactivation.
Does HHV-6B reactivation impair thymic function leading to delayed immune reconstitution?
HHV-6B directly infects thymocytes, presumably affecting thymopoeisis. A review in Bone Marrow Transplantation explores the intriguing relationship between HHV-6B, T-cell reconstitution and aGVHD after allogenic hematopoietic cell transplantation.
HHV-6 viremia impairs late T-cell reconstitution in HCT
Dutch investigators found that hematopoietic cell transplant patients with high levels of HHV-6 viremia have reduced late immune reconstitution while early reconstitution was not affected.
High rate of HHV-6 end-organ disease and mortality in pediatric transplant patients
Stanford investigators found that high levels of HHV-6 viremia following allogeneic stem cell transplants were associated end organ disease and greater non-relapse mortality.
Foscarnet prophylaxis reduces severity but does not prevent HHV-6 encephalitis
A Japanese trial of foscarnet prophylaxis in cord blood transplant patients was successful in reducing severity and mortality as well as suppressing high viral loads, but it failed to prevent encephalitis. The authors note that the blood brain barrier must be inflamed to allow effective penetration of the drug into the central nervous system and speculate that the prophylaxis may have protected the meninges.
HHV-6 acute liver failure in an immunocompetent child: case report
HHV-6 is rarely identified as the cause of liver dysfunction in immunocompetent children, in part because HHV-6 is not included in routine testing, and HHV-6 infections can be highly localized to the liver. In this case, an alert team in Arizona identified HHV-6 by needle biopsy.
HHV-6 myelitis after cord blood transplantation
Japanese investigators described HHV-6 myelitis in patients who had received cord blood transplantations and report that where HHV-6 reactivation is suspected, early antiviral intervention can dramatically improve patient outcomes.
HHV-6B reactivates first, proceeds to end organ disease faster in transplant patients
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%.