Dr. Jussi Oskari Virtanen, who works in Steve Jacobson’s laboratory at the NINDS, has published findings that further strengthen the relationship between HHV-6, EBV, and multiple sclerosis. The report demonstrates that 24% of 37 CSF samples from MS patients had HHV-6 reactive oligoclonal bands (OCBs) and 14% had EBV OCBs, compared to none in patients with other inflammatory neurological diseases (p=0.005). In addition, brain imaging analysis also showed that MS patients with viral DNA detected in the CSF exhibited more brain contrast enhancing lesions (CELs) than those who were virus-negative.
The authors of the study point out that several previous publications have identified OCBs reactive to HHV-6, EBV, and c. pneumonia in the spinal fluid of MS patients. In addition, while OCBs are a useful marker for the diagnosis of MS, they are not specific to the condition and can be found in patients with other demyelinating conditions as well. A recent report has linked OCB status in MS patients to specific genetic risk alleles, suggesting that there may be significant differences in disease mechanisms between OCB-negative and OCB-positive MS (Mero 2013).
Dr. Virtanen has also published previous work on HHV-6-specific OCBs through the University of Helsinki, Finland. His previous study found HHV-6 OCBs in 26% of 46 MS CSF samples compared to 21% of 24 CSF samples from patients with other demyelinating diseases such as optic neuritis, transverse myelitis and acute disseminated encephalomyelitis (ADEM) (Virtanen 2011). The present study contrasts MS patients and patients with HTLV-1 associated myelopathy and autoimmune encephalitis as controls. Previous studies have also found OCBs specific for c. pneumonia in both MS patients (particularly those with progressive forms of the condition) and those with other inflammatory demyelinating diseases (Fainardi 2009).
The NINDS report represents the first detailed analysis demonstrating significant MRI abnormalities in MS patients associated with the presence of virus and virus-reactive OCBs. Furthermore, the group utilized a rigorous multi-faceted approach for the detection of virus infection in this study, which included the use of an electrochemiluminescence (ECL)-based antibody assay as well as nested PCR for both HHV-6 and EBV. Virus reactive OCBs were detected via isoelectric focusing.
Taken together, the findings presented in this study add considerable weight to the notion of an etiological role for HHV-6 and EBV in MS. To test this hypothesis further, the group suggests the initiation of “well-designed antiviral clinical trials with safe, efficient and CNS-penetrable antiviral drugs.”