Distribution and quantification of human herpesvirus 6 in multiple sclerosis and control brains
P W Tuke1, S Hawke, P D Griffiths
1Centre for Virology, Department of Infection, Royal Free and University College Medical School of UCL, Hampstead Site, Rowland Hill Street, London NW3 2PF, UK.
Abstract:
Multiple sclerosis (MS) is thought to be precipitated by environmental factors, potentially including viruses, in genetically susceptible individuals and recently human herpesvirus 6 (HHV-6) has been associated with the disease. We have analysed post mortem brain for the presence, variant type and quantity of HHV-6 by PCR. A total of 124 samples from seven anatomically defined regions of brain were tested from MS cases and controls. HHV-6 DNA was detected in 41% and 44% of MS case and control samples. The median viral loads were 11 and 9 genome copies/microg DNA in cases and controls respectively and the viral load was not increased in lesions. Except in one instance, the HHV-6 DNA detected was variant B. There was no apparent difference in the distribution of HHV-6 DNA in the brains of MS cases versus controls, nor between normal appearing and lesional tissue in MS cases. Periventricular regions of the brain were more frequently positive for HHV-6 DNA in both MS cases and controls, although this difference was not statistically significant. These studies confirm the neurotropism of HHV-6 but do not demonstrate differences in the distribution, variant type or quantity of HHV-6 in brains from patients with MS versus controls.
Insights
Human herpesvirus 6 (HHV-6) DNA was detected in brains of multiple sclerosis (MS) patients and controls at similar levels. This study found no significant differences in HHV-6 presence, variant, or quantity in MS brains, suggesting it may not be a key factor.
Area of Science:
- Neurovirology
- Immunology
- Pathology
Background:
- Multiple sclerosis (MS) is an autoimmune disease with suspected environmental triggers.
- Human herpesvirus 6 (HHV-6) has been implicated as a potential environmental factor in MS pathogenesis.
- Understanding the role of viruses like HHV-6 in MS is crucial for disease etiology and treatment.
Purpose of the Study:
- To investigate the presence, variant type, and quantity of HHV-6 DNA in post-mortem brain samples from MS patients and controls.
- To determine if HHV-6 distribution or load differs between MS cases and healthy controls.
- To assess HHV-6 presence in both normal-appearing and lesional brain tissue in MS.
Main Methods:
- Post-mortem brain tissue samples from 124 individuals (MS cases and controls) were analyzed.
- Seven anatomically defined brain regions were tested for HHV-6 DNA using Polymerase Chain Reaction (PCR).
- Viral load was quantified, and HHV-6 variants were identified.
Main Results:
- HHV-6 DNA was detected in 41% of MS cases and 44% of control samples.
- Median viral loads were comparable between MS cases (11 genome copies/µg DNA) and controls (9 genome copies/µg DNA).
- No significant differences in HHV-6 distribution, variant type (predominantly variant B), or quantity were found between MS brains and controls, or in lesional versus normal-appearing tissue.
Conclusions:
- These findings confirm the neurotropic nature of HHV-6.
- The study does not support a significant role for HHV-6 in the pathogenesis of multiple sclerosis based on its presence, variant, or quantity in the brain.
- Further research may be needed to explore other potential environmental factors or mechanisms in MS etiology.
