Multiple Sclerosis-associated Retrovirus Research Articles

A Novel, Highly Selective RT-QPCR Method for Quantification of MSRV Using PNA Clamping Syncytin-1 (ERVWE1).

HERV-W is a multi-locus family of human endogenous retroviruses (HERVs) that has been found to play an important role in human physiology and pathology. Two particular members of HERV-W family are of special interests: ERVWE1 (coding syncytin-1, which is a glycoprotein essential in the formation of the placenta) and MSRV (multiple sclerosis-associated retrovirus that is thought to play a significant role in human pathology as a result of its increased expression in the brain tissue and blood cells derived from patients with multiple sclerosis (MS)). Both ERVWE1 and MSRV mRNA share high level of similarity and hence a method that allows to exclusively quantify the MSRV expression in clinical samples would be desirable. We developed a quantitative polymerase chain reaction (QPCR) technique for the detection and quantification of the multiple sclerosis-associated retrovirus. The assay utilises fluorescently labelled oligonucleotide probe, which is complementary to the conservative fragment of MSRV env gene and a peptide nucleic acid (PNA) probe, fully complementary to the ERVWE1 sequence fragment that efficiently blocks the polymerase action on ERVWE1 templates. The PNA molecule, if used parallel with hydrolysis probe in QPCR analysis, greatly facilitates the detection efficiency of MSRV even if ERVWE1 is present abundantly in respect to MSRV in the analysed sample. We achieved a wide and measurable range from 1 × 10 e2 to 1 × 10 e8 copies/reaction; the linearity of the technique was maintained even at the low MSRV level of 1 % in respect to ERVWE1. Using our newly developed method we confirmed that the expression of MSRV takes place in normal human astrocytes and in human umbilical vein endothelial cells in vitro. We also found that the stimulation of human monocytes did not influence the specific expression of MSRV but it caused changes in mRNA level of distinct HERV-W templates.

Inflammatory response of endothelial cells to a human endogenous retrovirus associated with multiple sclerosis is mediated by TLR4.

The MSRV (multiple sclerosis-associated retrovirus) belongs to the human endogenous retrovirus HERV-W family. The envelope protein originating from the MSRV has been found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties for several types of immune cells and could therefore play a role in MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We demonstrate that the recombinant MSRV envelope is able to stimulate several inflammatory parameters in a human BBB in vitro model, the HCMEC/D3 brain endothelial cell line. Indeed, Env-ms induces over-expression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner as well as a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a silencing approach with siRNAs, we show that Env-ms is recognized via the Toll-like receptor 4 receptor, a pattern recognition receptor of innate immunity present on endothelial cells. We also show, using functional assays, that treatment of brain endothelial cells with Env-ms significantly stimulated the adhesion and the transmigration of activated immune cells through a monolayer of endothelial cells. These findings support the hypothesis that MSRV could be involved in the pathogenesis of MS disease or at least in maintenance of inflammatory conditions, thus fueling the auto-immune disorder. MSRV could also play a role in other chronic inflammatory diseases.

Multiple sclerosis retrovirus-like envelope gene: Role of the chromosome 20 insertion

BackgroundThe genetic basis involved in multiple sclerosis (MS) susceptibility was not completely revealed by genome-wide association studies. Part of it could lie in repetitive sequences, as those corresponding to human Endogenous Retroviruses (HERVs). Retrovirus-like particles were isolated from MS patients and the genome of the MS-associated retrovirus (MSRV) was the founder of the HERV-W family. We aimed to ascertain which chromosomal origin encodes the pathogenic ENV protein by genomic analysis of the HERV-W insertions. Methods/resultsIn silico analyses allowed to uncover putative open reading frames containing the specific sequence previously reported for MSRV-like envelope (env) detection. Out of the 261 genomic insertions of HERV-W env, only 9 copies harbor the specific primers and probe featuring MSRV-like env. The copy from chromosome 20 was further studied considering its size, a truncated homologue of the functional HERV-W env sequence encoding syncytin. High Resolution Melting analysis of this sequence identified two single nucleotide polymorphisms, subsequently genotyped by Taqman chemistry in 668 MS patients and 678 healthy controls. No significant association of these polymorphisms with MS risk was evidenced. Transcriptional activity of this MSRV-like env copy was detected in peripheral blood mononuclear cells from patients and controls. RNA expression levels of chromosome 20-specific MSRV-like env did not show significant differences between MS patients and controls, neither were related to genotypes of the two mentioned polymorphisms. ConclusionsThe lack of association with MS risk of the identified polymorphisms together with the transcription results discard chromosome 20 as genomic origin of MSRV-like env.

HIV Tat acts on endogenous retroviruses of the W family and this occurs via Toll-like receptor 4: inference for neuroAIDS.

The objective of this study is to verify whether HIV activates two endogenous retroviruses of the human endogenous retrovirus (HERV)-W family, multiple sclerosis-associated retrovirus (MSRV) and Syncytin-1, whose neuropathogenic and immunopathogenic properties could contribute to HIV-related neurodegeneration. Peripheral blood mononuclear cells, monocyte-macrophages and astrocytes were either infected by HIV or exposed to HIV-Tat, and/or other treatments. The expression of transcripts and proteins of interest was evaluated by real-time RT-PCR and western blotting assays, respectively. HIV and Tat increase the levels of MSRVenv mRNAs and HERV-Wenv proteins in astrocytes and in blood cells. In monocyte-macrophages, Tat also induces high levels of CCR2, CD16 and Toll-like receptor 4 (TLR4) molecules. Syncytin-1 response to Tat depends on the cell context: in monocytes, Tat stimulates MSRVenv and inhibits Syncytin-1, while in differentiated macrophages, it stimulates both elements. In primary astrocytes, Tat stimulates MSRV and Syncytin-1 indirectly, through interaction with TLR4 and induction of tumour necrosis factor-alpha (TNFα), without internalization. In-vivo consequence of the study could be that, through increase of CD16 and CCR2, Tat promotes neuroinvasion not only by HIV-infected monocytes/macrophages but also by the HERV-Ws, with their neuropathogenic potential. Also, the novel finding of TLR4 stimulation by Tat may be of relevance, as TLR4 is critical in neuroinflammation. Within central nervous system (CNS), Tat-induced TNFα could induce high levels of the HERV-Ws, in both macrophages and astrocytes, also without HIV replication. The indirect mechanism by which Tat activates the HERV-Ws through induction of TNFα could add a new piece to the puzzle of CNS pathogenesis, that is the HERV-Wenv contribute to the HIV-related neurodegeneration.

A phase IIa randomised clinical study of GNbAC1, a humanised monoclonal antibody against the envelope protein of multiple sclerosis-associated endogenous retrovirus in multiple sclerosis patients

Background: GNbAC1 is an immunoglobulin (IgG4) humanised monoclonal antibody against multiple sclerosis-associated retrovirus (MSRV)-Env, a protein of endogenous retroviral origin, expressed in multiple sclerosis (MS) lesions, which is pro-inflammatory and inhibits oligodendrocyte precursor cell differentiation. Objective: This is a randomised, double-blind placebo-controlled dose-escalation study followed by a six-month open-label phase to test GNbAC1 in MS patients. The primary objective was to assess GNbAC1 safety in MS patients, and the other objectives were pharmacokinetic and pharmacodynamic assessments. Methods: Ten MS patients were randomised into two cohorts to receive a single intravenous infusion of GNbAC1/placebo at doses of 2 or 6 mg/kg. Then all patients received five infusions of GNbAC1 at 2 or 6 mg/kg at four-week intervals in an open-label setting. Safety, brain magnetic resonance imaging (MRI), pharmacokinetics, immunogenicity, cytokines and MSRV RNA expression were studied. Results: All patients completed the study. GNbAC1 was well tolerated in all patients. GNbAC1 pharmacokinetics is dose-linear with mean elimination half-life of 27–37 d. Anti-GNbAC1 antibodies were not detected. Cytokine analysis did not indicate an adverse effect. MSRV-transcripts showed a decline after the start of treatment. Nine patients had stable brain lesions at MRI. Conclusion: The safety, pharmacokinetic profile, and pharmacodynamic responses to GNbAC1 are favourable in MS patients over a six-month treatment period.

A peptide nucleic acid (PNA)-mediated polymerase chain reaction clamping allows the selective inhibition of the ERVWE1 gene amplification

A new peptide nucleic acid (PNA) mediated QPCR technique for the detection and quantification of the Multiple Sclerosis-Associated Retrovirus (MSRV) belonging to the human endogenous retrovirus-W (HERV-W) family has been developed. The assay utilizes a PNA probe which is fully complementary to the ERVWE1 sequence, another member of the HERV-W family which is closely related to MSRV. Due to its excellent affinity to a completely matched template, PNA probe selectively blocks the amplification of ERVWE1 thus allowing the specific and exclusive detection and quantification of the MSRV as PNA does not interfere with the amplification of MSRV. Using this newly developed method we found that MSRV is predominantly expressed over ERWVE1 in astrocyte-derived U-87 MG cell line but not in human umbilical vein endothelial cells or human placental cells.

HERV-W polymorphism in chromosome X is associated with multiple sclerosis risk and with differential expression of MSRV

BackgroundMultiple Sclerosis (MS) is an autoimmune demyelinating disease that occurs more frequently in women than in men. Multiple Sclerosis Associated Retrovirus (MSRV) is a member of HERV-W, a multicopy human endogenous retroviral family repeatedly implicated in MS pathogenesis. MSRV envelope protein is elevated in the serum of MS patients and induces inflammation and demyelination but, in spite of this pathogenic potential, its exact genomic origin and mechanism of generation are unknown. A possible link between the HERV-W copy on chromosome Xq22.3, that contains an almost complete open reading frame, and the gender differential prevalence in MS has been suggested.ResultsMSRV transcription levels were higher in MS patients than in controls (U-Mann–Whitney; p = 0.004). Also, they were associated with the clinical forms (Spearman; p = 0.0003) and with the Multiple Sclerosis Severity Score (MSSS) (Spearman; p = 0.016). By mapping a 3 kb region in Xq22.3, including the HERV-W locus, we identified three polymorphisms: rs6622139 (T/C), rs6622140 (G/A) and rs1290413 (G/A). After genotyping 3127 individuals (1669 patients and 1458 controls) from two different Spanish cohorts, we found that in women rs6622139 T/C was associated with MS susceptibility: [χ2; p = 0.004; OR (95% CI) = 0.50 (0.31-0.81)] and severity, since CC women presented lower MSSS scores than CT (U-Mann–Whitney; p = 0.039) or TT patients (U-Mann–Whitney; p = 0.031). Concordantly with the susceptibility conferred in women, rs6622139*T was associated with higher MSRV expression (U-Mann–Whitney; p = 0.003).ConclusionsOur present work supports the hypothesis of a direct involvement of HERV-W/MSRV in MS pathogenesis, identifying a genetic marker on chromosome X that could be one of the causes underlying the gender differences in MS.

HERV-W/MRSV envelope transcripts detection in blood of multiple sclerosis patients after Natalizumab treatment

Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system (CNS) and is the most common cause of neurological disability in young adults. MS-Associated Retrovirus (MSRV) is member of Human Endogenous Retroviruses W family, and their increased activity in MS patients is associated to the disease immunopathogenesis. Natalizumab, an antibody-based therapy, hinders migration of T cells into the CNS and is currently the most potent treatment for MS. Although Natalizumab interferes with gene expression relevant for function and differentiation of lymphocytes, its effects on genes involved in immunopathogenesis are unknown. Here, we report the effect of different treatments on the HERV-W/MRSV expression in patients with relapsing-remitting MS. MRSV transcripts were quantified by qRT-PCR in peripheral blood mononuclear cells of 9 patients receiving Natalizumab for at least 6 months (MSNat group) and 11 patients under immunosuppressive treatments (MSI group). The mean age was 28 years (18-35) for MSNat group and 44 (28-54) for MSI. The mean Expanded Disability Status Scale (EDSS) score was 4 (2-6) and 2.6 (1-6.5) for MSNat and MSI groups respectively. MSRV transcripts level was slightly higher in MSNat group, although not significantly, suggesting that Natalizumab does not interfere on HERV-W expression. Patients included in Natalizumab protocol usually do not respond to other treatments and present higher EDSSs. Possibly, EDSS and age have more impact in retroelements activity, as already demonstrated. This is the first comparison of HERV/MSRV expression between different therapy groups in MS, and other studies are needed to confirm such findings.

GNbAC1, a Humanized Monoclonal Antibody Against the Envelope Protein of Multiple Sclerosis—Associated Endogenous Retrovirus: A First-in-Humans Randomized Clinical Study

BackgroundHuman endogenous retrovirus (HERV) genes represent about 8% of the human genome. A member of the HERV family W, the Multiple Sclerosis–Associated Retrovirus (MSRV) gene, encodes an envelope protein (Env), which can activate a proinflammatory and autoimmune cascade through its interaction with Toll-like receptor 4. Due to its proinflammatory property and an inhibitory effect on oligodendrocyte precursor cell differentiation, the MSRV-Env protein could play a crucial role in the pathogeny of multiple sclerosis. GNbAC1 is a humanized monoclonal antibody of the immunoglobulin G4 type, which is directed against MSRV-Env. After validation of the MSRV-Env as a therapeutic target in preclinical experimental models, a clinical development program was initiated. ObjectiveThis study evaluated the safety profile, pharmacokinetic parameters, and immunogenicity of GNbAC1 in healthy male volunteers. MethodsIn this first-in-humans, Phase I, randomized, double-blind, placebo-controlled, dose-escalation study, each subject received a single dose of IV GNbAC1 0.0025, 0.025, 0.15, 0.6, 2, or 6 mg/kg or inactive vehicle (placebo), infused over 1 hour. Tolerability and other laboratory parameters were observed, and regular blood sampling was performed, to study the pharmacokinetic properties and immunogenicity of this monoclonal antibody. ResultsA total of 33 male subjects (mean age, 44 years) completed the study. GNbAC1 was well tolerated after dosing in all subjects and in each dose cohort. Only minor and nonspecific adverse events (AEs) were recorded; no serious AEs were reported. Pharmacokinetic data show a dose-linear pharmacokinetic profile. The mean elimination half-life ranged between 19 and 26 days, with therapeutically efficient concentrations maintained over a 4-week periods at doses of 2 and 6 mg/kg. No emergence of anti-GNbAC1 antibodies were detected after dosing in any subject over the entire observation period of 64 days. ConclusionsIn these healthy male subjects, the safety and pharmacokinetic profiles of GNbAC1 appeared favorable. These findings are expected to allow for the launch of a Phase II development program for this innovative therapeutic approach in patients with multiple sclerosis. ClinicalTrials.gov identifier: NCT01699555.

Expression and Activation by Epstein Barr Virus of Human Endogenous Retroviruses-W in Blood Cells and Astrocytes: Inference for Multiple Sclerosis

BackgroundProposed co-factors triggering the pathogenesis of multiple sclerosis (MS) are the Epstein Barr virus (EBV), and the potentially neuropathogenic MSRV (MS-associated retrovirus) and syncytin-1, of the W family of human endogenous retroviruses.Methodology/Principal FindingsIn search of links, the expression of HERV-W/MSRV/syncytin-1, with/without exposure to EBV or to EBV glycoprotein350 (EBVgp350), was studied on peripheral blood mononuclear cells (PBMC) from healthy volunteers and MS patients, and on astrocytes, by discriminatory env-specific RT-PCR assays, and by flow cytometry. Basal expression of HERV-W/MSRV/syncytin-1 occurs in astrocytes and in monocytes, NK, and B, but not in T cells. This uneven expression is amplified in untreated MS patients, and dramatically reduced during therapy. In astrocytes, EBVgp350 stimulates the expression of HERV-W/MSRV/syncytin-1, with requirement of the NF-κB pathway. In EBVgp350-treated PBMC, MSRVenv and syncytin-1 transcription is activated in B cells and monocytes, but not in T cells, nor in the highly expressing NK cells. The latter cells, but not the T cells, are activated by proinflammatory cytokines.Conclusions/Significance In vitro EBV activates the potentially immunopathogenic and neuropathogenic HERV-W/MSRV/syncytin-1, in cells deriving from blood and brain. In vivo, pathogenic outcomes would depend on abnormal situations, as in late EBV primary infection, that is often symptomatic, or/and in the presence of particular host genetic backgrounds. In the blood, HERV-Wenv activation might induce immunopathogenic phenomena linked to its superantigenic properties. In the brain, toxic mechanisms against oligodendrocytes could be established, inducing inflammation, demyelination and axonal damage. Local stimulation by proinflammatory cytokines and other factors might activate further HERV-Ws, contributing to the neuropathogenity. In MS pathogenesis, a possible model could include EBV as initial trigger of future MS, years later, and HERV-W/MSRV/syncytin-1 as actual contributor to MS pathogenicity, in striking parallelism with disease behaviour.

Regulation of human endogenous retroviruses of the W family by type III interferon λ2 and HIV in astrocytes

Astrocytes play a key role in important neurological diseases such as multiple sclerosis (MS) and neuroAIDS. The multiple sclerosis-associated retrovirus (MSRV) is an active member of the W family of human endogenous retroviruses (HERV), able to produce extracellular particles; another HERV-W element is ERVWE1, producing only an env protein, named syncytin-1, that can be found intracellularly and on the plasma-membrane, but not extracellularly. MSRVenv and syncytin-1 proteins have pro-inflammatory properties that might be pathogenic, as observed in vitro and in animal models: they may cause neuroinflammation, neurodegeneration, alterations of the immune system and stress responses; both have been suggested as co-factors triggering the immunopathogenesis of MS.λ2 has been shown to favour the replication of exogenous retroviruses, such as HIV, we designed studies to detect possible effects of IFNλ2 on the above HERV-W retroelements in U87 MG astrocytes, by using real time RT-PCR assays that can selectively identify either MSRVenv or syncytin-1 transcripts.. Treatment of astrocytes with IFNλ2 was found to enhance the expression of both MSRVenv and syncytin-1, dose-dependently. If cells are infected by HIV, the expression of both elements is modified. Surprisingly, HIV caused opposite effects on the two HERV-W retroelements, since MSRVenv transcription was up-regulated, whilst that of syncytin-1 was down-regulated. Cell pre-treatment with IFNλ2 did not alter the effects of subsequent HIV infection on MSRVenv and syncytin-1. behaves as a pro-inflammatory cytokine, that can facilitate the expression of both exogenous and endogenous human retroviruses. Since Type III IFN. This cell line has the IL-28R receptor, and is sensitive to IFNλ2. It is totally unknown the role played by Type III IFN in neuropathologies like neuro-AIDS and MS, but it could be hypothesized that IFNλ.

Novel reliable real-time PCR for differential detection of MSRV env and syncytin-1 in RNA and DNA from patients with multiple sclerosis

Two components of the HERV-W family of human endogenous retroviruses are activated during multiple sclerosis (MS) and proposed immunopathogenic co-factors: MSRV (MS-associated retrovirus), and ERVWE1 (whose env protein, syncytin-1, reaches the plasma membrane). MSRV env and syncytin-1 are closely related, and difficult to distinguish each other. The sequences of extracellular MSRV env and of syncytin-1 available in GenBank were compared with those found in MS patients and controls of the cohort under study. With respect to syncytin-1, MSRV env sequences have a 12-nucleotide insertion in the trans-membrane moiety. Based on this insertion, discriminatory real-time PCR assays were developed, that can amplify selectively either MSRV env or syncytin-1. The data of MS patients and controls indicated that MSRV and ERVWE1 are both expressed in the brain of MS patients, while only MSRV is present in the blood; MSRV was released in culture by PBMCs of MSRV-producer individuals. These cells expressed the complete MSRV env gene in the absence of syncytin-1 expression, up to the final, fully glycosylated envelope protein product, since western blot staining with anti-HERV-Wenv antibody detected two bands of the same molecular weight (73 and 61 kDa) of the fully glycosylated and partially glycosylated HERV-Wenv uncleaved proteins. Beyond MSRV env DNA copy numbers were more abundant in MS patients than in healthy humans, while syncytin-1 were unchanged. These findings reinforce the link between MSRV and MS.

Analysis of transcribed human endogenous retrovirus W env loci clarifies the origin of multiple sclerosis-associated retrovirus envsequences

BackgroundMultiple sclerosis-associated retrovirus (MSRV) RNA sequences have been detected in patients with multiple sclerosis (MS) and are related to the multi-copy human endogenous retrovirus family type W (HERV-W). Only one HERV-W locus (ERVWE1) codes for a complete HERV-W Env protein (Syncytin-1). Syncytin-1 and the putative MSRV Env protein have been involved in the pathogenesis of MS. The origin of MSRV and its precise relation to HERV-W were hitherto unknown.ResultsBy mapping HERV-W env cDNA sequences (n = 332) from peripheral blood mononuclear cells of patients with MS and healthy controls onto individual genomic HERV-W env elements, we identified seven transcribed HERV-W env loci in these cells, including ERVWE1. Transcriptional activity of individual HERV-W env elements did not significantly differ between patients with MS and controls. Remarkably, almost 30% of HERV-W env cDNAs were recombined sequences that most likely arose in vitro between transcripts from different HERV-W env elements. Re-analysis of published MSRV env sequences revealed that all of them can be explained as originating from genomic HERV-W env loci or recombinations among them. In particular, a MSRV env clone previously used for the generation of monoclonal antibody 6A2B2, detecting an antigen in MS brain lesions, appears to be derived from a HERV-W env locus on chromosome Xq22.3. This locus harbors a long open reading frame for an N-terminally truncated HERV-W Env protein.ConclusionOur data clarify the origin of MSRV env sequences, have important implications for the status of MSRV, and open the possibility that a protein encoded by a HERV-W env element on chromosome Xq22.3 may be expressed in MS brain lesions.

Unreliable Real-Time PCR Analysis of Human Endogenous Retrovirus-W (HERV-W) RNA Expression and DNA Copy Number in Multiple Sclerosis

Unreliable Real-Time PCR Analysis of Human Endogenous Retrovirus-W (HERV-W) RNA Expression and DNA Copy Number in Multiple Sclerosis

The multiple sclerosis-associated retrovirus and its HERV-W endogenous family: a biological interface between virology, genetics, and immunology in human physiology and disease

This mini-review summarizes current knowledge of MSRV (multiple sclerosis-associated retrovirus), founder member of the type W family of human endogenous retroviruses (HERVs), its pathogenic potential and association with diseases. As retrotransposable elements, HERVs behave differently from stable genes, and cannot be studied with "Mendelian genetics" concepts only. They also display complex interactions with other HERV families, and with classical viruses. These concepts may contribute to unravelling the etiopathogenesis of complex diseases such as multiple sclerosis, schizophrenia, and other chronic multifactorial diseases.

Inhibition of multiple sclerosis–associated retrovirus as biomarker of interferon therapy

The authors performed a longitudinal evaluation of multiple sclerosis (MS) patients, during 1 year of therapy with interferon-beta (IFN-beta), by clinical examination and detection of presence in the blood and viral load of MS-associated retrovirus (MSRV), by MSRVenv-specific, fully quantitative, real time reverse transcriptase-polymerase chain reaction (RT-PCR). MSRV load in the blood was directly related to MS duration and fell below detection limits within 3 months of IFN therapy; one patient had strong progression, accompanied by total MSRV rescue. These findings suggest that evaluation of plasmatic MSRV could be considered the first prognostic marker for the individual patient, to monitor disease progression and therapy outcome.

Lack of immune responses against multiple sclerosis–associated retrovirus/human endogenous retrovirus W in patients with multiple sclerosis

The multiple sclerosis-associated retrovirus (MSRV), originally identified in cell cultures from patients with multiple sclerosis (MS), is closely related to the human endogenous retrovirus family type W (HERV-W). Different lines of evidence appear compatible with a potential role of MSRV/HERV-W in the pathogenesis of MS. The authors therefore analyzed humoral and cellular immune responses against MSRV/HERV-W antigens in patients with MS, patients with other inflammatory and noninflammatory neurological diseases, and healthy controls, using indirect immunofluorescence and enzyme-linked immunospot assays. Antibodies against the HERV-W envelope (Env) protein, Syncytin-1, were found in one of 50 patients with MS and none of 59 controls, whereas antibodies against MSRV matrix and capsid (Gag) or Env proteins were not detectable in any of the patients or controls. Similarly, in a screening of human leukocyte antigen (HLA)-B7+ patients with MS (n = 23) and controls (n = 29) for cytotoxic T-lymphocyte responses against 36 predicted HLA-B7-restricted MSRV/HERV-W Gag-, protease-, and reverse transcriptase-derived peptides, no such responses could be detected in any of the subjects studied. These data suggest that there are no appreciable humoral or cellular immune responses against MSRV/HERV-W in patients with MS. While this may be due to immunological tolerance of physiologically expressed HERV-W proteins, strategies other than measurement of immune responses will be required to further elucidate the relationship between MSRV/HERV-W and MS.

Brains and peripheral blood mononuclear cells of multiple sclerosis (MS) patients hyperexpress MS-associated retrovirus/HERV-W endogenous retrovirus, but not Human herpesvirus 6

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.

Multiple sclerosis-associated retrovirus in early multiple sclerosis: a six-year follow-up of a Sardinian cohort

The human endogenous retroviruses (HERV)-W family contains an extracellular particle detected in multiple sclerosis (MS) patients and designated as MS-associated retrovirus (MSRV). Through nested RT-PCR assays specific for pol MSRV gene, we preliminary reported that its presence in the cerebrospinal fluid (CSF) of early MS patients could be indicative of a poor prognosis upon a three-year follow-up. In the present clinical study, we enlarged our blind observation up to six years. At study entry, 10 MS patients were MSRV- and eight were MSRV+ in the CSF, both groups having a similar mean age and Expanded Disability Status Scale (EDSS) score. After six year follow-up, the mean EDSS significantly differed between the MSRV- and MSRV+ cohorts (4.3 versus 2.2; P = 0.004), as did the annual relapse rate (0.5 in the MSRV- versus 0.3 in the MSRV+; P = 0.01). Finally, two MSRV- patients entered the progressive phase, whilst none of the MSRV+ group entered this phase, and 9/10 MSRV- versus 2/8 MSRV+ patients were treated with immunomodulatory or immunosuppressive drugs (P = 0.009). In conclusion, we found that the presence of MSRV virions in the CSF at the onset of MS is associated, not only with disability accumulation, but also with a higher rate of clinical re-exacerbations. With the known potential pathogenic effects of MSRV given in the literature, further investigations on MSRV are warranted.

Analysis of viral and genetic factors in South African patients with multiple sclerosis

A significant association was previously demonstrated between multiple sclerosis (MS) and the functional 5'-(GT)n polymorphism in the promoter region of the SLC11A1 gene, which has been implicated in both autoimmune and infectious disease susceptibility. In the present study the role of viral infection was investigated in South African MS patients in relation to specific SLC11A1 genotypes. Serum and peripheral blood mononuclear cells (PBMC) of 49 MS patients, 33 close relatives and 39 unrelated controls previously genotyped for SLC11A1 were screened for the presence of MS-associated retrovirus (MSRV) and two herpes virus (HHV-6 and EBV) sequences. Expression of the pol gene of MSRV was detected in the serum RNA of 34/49 (69%) MS patients whilst absent in the serum of 39 unrelated healthy control individuals (p < 0.001) but was also present in 23/33 (70%) of the unaffected close relatives of the patients. HHV-6 and EBV sequences were detected in both MS patients and control individuals. The viral sequences were not confined to a specific SLC11A1 genotype. Infection with these viruses is excluded as the primary cause for MS in the South African population since no significant differences were detected between MS patients and their unaffected close family members.