%0 Journal Article %A Mameli, Giuseppe %A Astone, Vito %A Arru, Giannina %A Marconi, Silvia %A Lovato, Laura %A Serra, Caterina %A Sotgiu, Stefano %A Bonetti, Bruno %A Dolei, Antonina %T Brains and peripheral blood mononuclear cells of multiple sclerosis (MS) patients hyperexpress MS-associated retrovirus/HERV-W endogenous retrovirus, but not Human herpesvirus 6 %D 2007 %J Journal of General Virology, %V 88 %N 1 %P 264-274 %@ 1465-2099 %R https://doi.org/10.1099/vir.0.81890-0 %I Microbiology Society, %X 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. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.81890-0