Strong association with MS

There appears to be a strong association with HHV-6 with Multiple Sclerosis (MS) yet research proving a causal relationship has been hampered by reported negative studies that used incorrect testing methodology. Because latent infection is so widespread, only tests that can differentiate between the active and latent infection are meaningful. Since over 95% of us have been exposed to the virus and most carry latent infection, this distinction is critical.
 
Several studies have been published using tests that don’t differentiate between active and latent infection. These studies showed no association between HHV-6 and MS, contradicting many positive studies and creating confusion. In the 39 studies that used tests that can detect active infection, 29 or 78% of them found a positive association. In the 20 studies that used tests that pick up latent as well as active virus, an association was found only 55% of the time.
 
Details of studies on the association of HHV-6 & MS
Reasons to suspect a virus in MS
 
The most recent test done last year by Alvarez-Lafuente using a messenger RNA test (which only detects active infections) 16% of 154 relapsing remitting MS patients had active virus compared to 0% of  49 controls. Unfortunately PCR tests on serum are not very sensitive for HHV-6 because the virus rarely  leaves to cell and only likes to replicate in the tissues. For this reason, some experts believe that the incidence of active infection is significantly understated in these studies and that there is a need for improved test methods to define the true incidence of active infection associated with MS.
 
Early Antigen testing:

When the best testing method (a test that measures “early antigen” (EA) IgM antibodies or active infection only) has been used, there have been dramatic disease associations suggesting an important role for HHV-6 in these conditions.
 
* Researchers at the NIH found that 73% of MS patients with relapsing remitting disease were positive for HHV-6A IgM antibodies to EA vs. 18% of normal controls. (Soldan et al, Nature, 1997)
 
* Ablashi et al found 70% of MS patients had HHV-6 IgM antibodies against the early antigen vs. 15% of healthy donors. (J Clin Virol, 2000)
 
This test is much more sensitive but it also picks up the less pathogenic B variant, that will reactivate in many health patients when they have a cold or other illness. The Foundation believes the best test would be a sensitive assay that picks up only the A variant and is actively working with researchers to get this test on the market.

For more information on HHV-6 and specific conditions:

        HHV-6 & MS
        HHV-6 & CFS
        HHV-6 & Cancer