Hip
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In 2012, the International Committee on Taxonomy of Viruses classified HHV-6A and HHV-6B as separate viruses (prior to that they were considered subtypes of HHV-6). Ref: 1
However, even though HHV-6A is a distinct and separate virus, since nearly all HHV-6 tests cannot distinguish between HHV-6A and HHV-6B, and since HHV-6 is found in nearly everybody (so nearly all HHV-6 tests are going to come back positive for having the virus), by standard labs tests, it is hard to know whether you might have HHV-6A or not.
According to the HHV-6 Foundation, testing laboratories that can detect HHV-6A include:
• Viracor-IBT Laboratories — HHV-6 Quantitative Real-time PCR
• Focus Diagnostics
• Wisconsin Viral Research, who have now become Coppe Labs.
HHV-6A seems to be a significant virus for ME/CFS:
One study of 36 ME/CFS patients and 24 healthy controls found HHV-6A in the peripheral blood mononuclear cells (PBMC) of 22% of ME/CFS patients, but only in 4% of healthy controls.
This study of 13 ME/CFS patients and 13 healthy controls found HHV-6A in the PBMCs of 31% of patients, HHV-6B in the PBMCs of 23% of patients, and no HHV-6A nor HHV-6B found in the PBMCs of healthy controls.
However, although the above studies found little to no HHV-6A or HHV-6B in the PBMCs of healthy controls, somewhat confusingly, this study of healthy individuals found HHV-6A in 16% of subjects' PBMCs, and HHV-6B in 98% of subjects' PBMCs.
However, even though HHV-6A is a distinct and separate virus, since nearly all HHV-6 tests cannot distinguish between HHV-6A and HHV-6B, and since HHV-6 is found in nearly everybody (so nearly all HHV-6 tests are going to come back positive for having the virus), by standard labs tests, it is hard to know whether you might have HHV-6A or not.
According to the HHV-6 Foundation, testing laboratories that can detect HHV-6A include:
• Viracor-IBT Laboratories — HHV-6 Quantitative Real-time PCR
• Focus Diagnostics
• Wisconsin Viral Research, who have now become Coppe Labs.
HHV-6A seems to be a significant virus for ME/CFS:
One study of 36 ME/CFS patients and 24 healthy controls found HHV-6A in the peripheral blood mononuclear cells (PBMC) of 22% of ME/CFS patients, but only in 4% of healthy controls.
This study of 13 ME/CFS patients and 13 healthy controls found HHV-6A in the PBMCs of 31% of patients, HHV-6B in the PBMCs of 23% of patients, and no HHV-6A nor HHV-6B found in the PBMCs of healthy controls.
However, although the above studies found little to no HHV-6A or HHV-6B in the PBMCs of healthy controls, somewhat confusingly, this study of healthy individuals found HHV-6A in 16% of subjects' PBMCs, and HHV-6B in 98% of subjects' PBMCs.
Some HHV-6A Info
HHV-6A is a more neurotropic virus than HHV-6B.
HHV-6A is acquired later in life, usually without clinical symptoms, except in Africa where HHV-6A is more prevalent than HHV-6B in children. Ref: 1
HHV-6A may act a cofactor with HIV in the progression to AIDS, since progression to full-blown AIDS is dramatically accelerated by HHV-6A. Ref: 1
HHV-6A is more prevalent in multiple sclerosis, an autoimmune disorder. Ref: 1
HHV-6A is associated with Hashimoto's thyroiditis, an autoimmune disorder. Ref: 1
It is only possible to differentiate HHV-6A from HHV-6B using a PCR DNA test. Ref: 1
HHV-6A may gain entry into the brain via the olfactory pathway. Ref: 1
HHV-6A has been found to persist in the spinal fluid long after it has disappeared from the plasma. Ref: 1
HHV-6A is more likely to be found in the spinal fluid or serum, whereas HHV-6B is more likely to be found in the white blood cells and in the saliva. Ref: 1
HHV-6A is not found in the saliva, ref: 1 2 (although this study says it is).
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