Rational vaccine design requires understanding details of protective immunity against each virus. Yasuko Mori and associates from Japan have now identified CD4+ and H-2Kd restricted CD8+ T-cell epitopes essential for HHV-6B viral entry, opening new possibilities for vaccines and immunotherapy.
Yasuko Mori and colleagues were successful in humanizing two neutralizing monoclonal antibodies to HHV-6B. The chimeric antibodies performed well enough to show promise for therapeutic use.
A Chinese group found HHV-6 direct repeat 7 in 48% of glioma tumors. Furthermore, they determined that DR7 overexpression could promote glioma cell migration, invasion and angiogenesis. Expression profiles showed that DR7 created an inflammatory microenvironment that enhanced degradation of the extracellular matrix.
Chinese investigators determined that human leukocyte antigen polymorphism HLA-B*13:01 and HHV-6 DNA blood positivity were not only independently associated with occupational trichloroethylene hypersensitivity, they had an interactive effect, increasing the odds ratio to 92.
A number of astronauts have complained about herpesvirus reactivations during flight, and several developed shingles. Investigators at NASA determined that space flight increases herpesvirus shedding in saliva, compared to levels before and after their missions.
A new study reports a surprisingly low rate of HHV-6 reactivation in recipients of half-matched bone marrow grafts using a reduced-intensity conditioning regimen. The authors speculate that the corticosteroid used for prophylaxis may have suppressed cytokine production which in turn limited reactivation of HHV-6.
Although foscarnet is widely used for HHV-6 encephalitis, it has never been specifically approved for HHV-6. Japan’s Ministry of Health, Labor and Welfare was the first to approve foscarnet (Foscavir) for the treatment of HHV-6 encephalitis.
Investigators from University of Michigan have demonstrated that murine roseolovirus is a useful homolog for the study of HHV-6 reactivation in lung disease. In a large retrospective study of HCT patients, they also found early HHV-6 reactivation to increase the risk of both idiopathic pneumonia syndrome and non-relapse mortality.
MS patients with a particular haplotype on natural killer cells are more susceptible to HHV-6A infection. Similarly, HHV-6A/B may contribute to Alzheimer’s by utilizing a specific NK cell inhibitory receptor to disrupt the ability of NK cells to clear infected cells.
An analysis of 165 central nervous system viral infections by the Center for International Blood and Bone Marrow Transplant Research found that most were positive for HHV-6. The outcome for patients with viral infection was poor with 50% mortality within 6 months and only 30% survival at 5 years.
Investigators from the Children’s Hospital of Mexico found that although CMV caused the biggest increase in risk for liver rejection, HHV-6 was the more important infection associated with rejection of kidney transplants. A single HHV-6 infection resulted in an increased risk of over 5 fold, while a coinfection of EBV, HHV-6 and HHV-7 increased the risk of kidney rejection by over 17 fold.
Herpesviruses are common in the trigeminal and facial ganglia, latently infecting 64% of cases. HHV-6 was the most commonly identified herpesvirus in these tissues — about half of all autopsy specimens were found to have the virus in trigeminal and/or facial ganglia.
HHV-6 was found to be significantly correlated with nerve fiber damage severity by Latvian investigators. 51% of fibromyalgia patients had detectable HHV-6 DNA in whole blood compared to just 6% of controls.
Since its discovery, HHV-6 has been studied in the context of lymphoproliferative disorders and various types of cancer. Several obstacles, particularly the ubiquitous nature of the virus, have made it difficult to determine exactly how HHV-6 might, or might not, be involved in tumor development.