This study examined the association between HHV-6 infection and Multiple Sclerosis (MS) and the relationship between HHV-6 re-activation and disease activity.
The frequency of HHV-6 genomic sequences in Peripheral Blood MonoNuclear Cells (PBMCs), the incidence of plasma viremia (nPCR), the transcription of Viral mRNA in PBMCs (RT-PCR), and the presence of AntiViral IgM and IgG class AntiBodies.
In the plasma (IFA) of 16 Relapsing/Remitting and Secondary/Progressive MS patients were studied in comparison with clinical manifestations of the disease, Magnetic Resonance Imaging (MRI) of Brain, and Serum InterLeukin-12 (IL-12) concentrations (ELISA).
The prevalence of HHV-6 infection was significantly higher in patients with MS (16/26) than in patients with other Neurological diseases (6/21) and in blood donors (43/150).
HHV-6 re-activation was found during periods of disease activity with Gadolinium-enhancing lesions on MRI in both Relapsing/Remitting and Secondary/Progressive MS (10/13; 76.9%).
In patients with active MS disease, Serum concentrations of IL-12 were significantly higher in those patients with active HHV-6 infection than in patients with latent infection.
The data confirm an association between HHV-6 infection and MS and show a correlation between HHV-6 re-activation and disease activity in Relapsing/Remitting and Secondary/Progressive MS.
The risk of an exacerbation of MS was significantly higher (P < 0.005) in patients with active HHV-6 infection than in patients with latent infection.
A clear correlation between HHV-6 re-activation and Serum IL-12 concentrations during disease activity has been demonstrated. The results suggest that HHV-6 re-activation is implicated in exacerbation of MS, possibly through modulation of IL-12 synthesis.
Copyright 2003 Wiley-Liss, Inc.