Brains and peripheral blood mononuclear cells of multiple sclerosis (MS)
patients hyperexpress MS-associated retrovirus/HERV-W endogenous retrovirus,
but not Human herpesvirus 6
Giuseppe Mameli1, Vito Astone1, Giannina Arru2, Silvia Marconi3, Laura
Lovato3, Caterina Serra1, Stefano Sotgiu2, Bruno Bonetti3 and Antonina
Dolei1
1 Section of Microbiology, Department of Biomedical Sciences, Center of
Excellence for Biotechnology Development and Biodiversity Research,
University of Sassari, Sassari, Italy
2 Institute of Clinical Neurology, University of Sassari, Sassari, Italy
3 Section of Neurology, Department of Neurological Sciences and Vision,
University of Verona, Verona, Italy
Correspondence
Antonina Dolei
doleivir@uniss.it
Multiple sclerosis (MS)-associated retrovirus (MSRV)/HERV-W (human
endogenous retrovirus W) and Human herpesvirus 6 (HHV-6) are the two most
studied (and discussed) viruses as environmental co-factors that trigger MS
immunopathological phenomena. Autopsied brain tissues from MS patients and
controls and peripheral blood mononuclear cells (PBMCs) were analysed.
Quantitative RT-PCR and PCR with primers specific for MSRV/HERV-W env and
pol and HHV-6 U94/rep and DNA-pol were used to determine virus copy numbers.
Brain sections were immunostained with HERV-W env-specific monoclonal
antibody to detect the viral protein. All brains expressed MSRV/HERV-W env
and pol genes. Phylogenetic analysis indicated that cerebral
MSRV/HERV-W-related env sequences, plasmatic MSRV, HERV-W and ERVWE1
(syncytin) are related closely. Accumulation of MSRV/HERV-W-specific RNAs
was significantly greater in MS brains than in controls (P=0.014 vs healthy
controls; P=0.006 vs pathological controls). By immunohistochemistry, no
HERV-W env protein was detected in control brains, whereas it was
upregulated within MS plaques and correlated with the extent of active
demyelination and inflammation. No HHV-6-specific RNAs were detected in
brains of MS patients; one healthy control had latent HHV-6 and one
pathological control had replicating HHV-6. At the PBMC level, all MS
patients expressed MSRV/HERV-W env at higher copy numbers than did controls
(P=0.00003). Similar HHV-6 presence was found in MS patients and healthy
individuals; only one MS patient had replicating HHV-6. This report, the
first to study both MSRV/HERV-W and HHV-6, indicates that MSRV/HERV-W is
expressed actively in human brain and activated strongly in MS patients,
whilst there are no significant differences between these MS patients and
controls for HHV-6 presence/replication at the brain or PBMC level.