A comprehensive, large-scale analysis has provided strong evidence of a causal association between HHV-6A and Alzheimer’s Disease. Not only was HHV-6A (and HHV-7) viral load found to be higher, but transcription of HHV-6A genes was also increased among AD patients, and this was observed across multiple brain regions and multiple cohorts. Importantly, host genes affected by HHV-6A were all associated with AD traits and risk genes.
Antibodies to HHV-6 and VZV dUTPases were significantly elevated in Gulf War Illness patients compared to controls, and EBV dUTPase antibodies were elevated in Chronic Fatigue Syndrome patients.
HHV-6B induces unique, region-specific DNA hypomethylation, and findings suggest that the epigenetic modification may facilitate HHV-6B integration.
Investigators from Uppsala University in Sweden found that HHV-6 IgG reactivity was significantly lower in Alzheimer’s Disease patients compared to controls. The authors suggest reduced immunity may be one reason why past studies have found increased levels of HHV-6 DNA in the brains of Alzheimer’s patients compared to controls.
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.
Australian investigators studied 143 young children with febrile seizures for signs of viral infection and found that HHV-6 was the fifth most common virus after rhinovirus (22%), enterovirus (20%), adenovirus (21%) and influenza (13%). Overall, a virus was found in 71% of cases. Virus found in complex seizures was associated with HHV-6 (42%) or influenza (41%).
A new point-of-care assay from bioMérieux can simultaneously and rapidly detect 14 pathogens typically found in encephalitis. The machine is designed to be at the clinic or in the emergency room and can be operated by unskilled technicians. In a study of 1,560 immunocompetent patient samples, a total of 1.35% were positive for HHV-6, or about twice the expected rate of 0.8% found with the inherited chromosomally integrated HHV-6.
A fifth case of limbic encephalitis associated with GAD antibodies and HHV-6 infection has been reported, this time in an immunocompetent woman with chromosomally integrated HHV-6, epilepsy, and psychosis. The patient’s condition improved (with a drop in GAD antibody titers and stabilization of psychotic symptoms) in response to three weeks of antiviral therapy but relapsed when antiviral therapy was withdrawn.
An Italian study on immunocompetent children with suspected CNS infections found HHV-6 and HHV-7 DNA in 4.2% and 4.8% of 304 cerebrospinal fluid (CSF) samples, respectively. Although once considered rare in the immunocompetent, recent studies with more sensitive methods have found HHV-6 in the CSF of 4-17% of immunocompetent children with seizures or suspected CNS infections.
Investigators associated with a dementia center at Kobe University Hospital found that saliva HHV-6 DNA levels may serve as an objective marker for caregiver exhaustion. The saliva HHV-6 DNA levels in caregivers (log 3.04 copies/ ml) were significantly higher than in those of non-caregivers (2.78 copies/ml).
Three virologists led by Kazuhiro Kondo, MD, PhD, a professor of virology at Jikei University School of Medicine, have filed a patent on a method to diagnose and treat prevent mood disorders which he says are initiated by latent and neurovirulent HHV-6B residing in glial cells, and that this condition can be treated effectively with nasal sprays, using the olfactory nerve as a route to the brain. Dr. Kondo has named this protein SITH-1 or “small protein encoded by intermediate state transcript”.
A group from Sapporo Medical University studied 105 post HSCT patients and determined that 7 developed CNS dysfunction in the first 42 days after transplant. Six out of the 7 were positive for HHV-6, but none of the other 12 pathogens tested. Four patients (3.8%) were diagnosed with HHV-6 encephalitis. The group used a qualitative multiplex PCR and then used a quantitative PCR to confirm the results.