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Natalizumab is effective against relapsing-remitting multiple sclerosis (MS) but increases the risk of progressive multifocal leukoencephalopathy (PML), which is caused by the activation of the JCV polyomavirus. SF2/ASF (splicing factor2/alternative splicing factor) is a potent cellular inhibitor of JCV replication and large T-antigen (T-Ag) expression. We reported that SF2/ASF levels in blood cells increase during the first year of natalizumab therapy and decrease thereafter, inversely related to T-Ag expression, and suggested a correlation with JCV reactivation. Here, we report SF2/ASF levels of longitudinal blood samples of two patients undergoing natalizumab therapy, who developed PML while monitored, in comparison to natalizumab-treated controls and to one-off PML samples. After 6 months of therapy, SF2/ASF levels of the two cases were reduced, instead of increased, and their overall SF2/ASF levels were lower than those from natalizumab controls. Since SF2/ASF inhibits JCV, its early reduction might have a role in subsequent PML. We are aware of the limitations of the study, but the uniqueness of serial blood samples collected before and after PML onset in natalizumab-treated patients must be stressed. If confirmed in other patients, SF2/ASF evaluation could be a new and early biomarker of natalizumab-associated PML risk, allowing an 18-24-month interval before PML onset (presently ~ 5 months), in which clinicians could evaluate other risk factors and change therapy.

The JC polyomavirus (JCV) has been repeatedly but discordantly detected in healthy colonic mucosa, adenomatous polyps, and colorectal cancer (CRC), and proposed to contribute to oncogenesis. The controversies may derive from differences in JCV targets, patient&rsquo, s cohorts, and methods. Studies of simultaneous detection, quantification, and characterization of JCV presence/expression in paired samples of normal/altered tissues of the same patient are lacking. Therefore, we simultaneously quantified JCV presence (DNA) and expression (mRNA and protein) of T-antigen (T-Ag), Viral Protein 1 (Vp1), and miR-J1-5p in paired normal/altered tissues of CRC or polyps, and from controls. JCV signatures were found in most samples. They increased in patients, but were higher in normal mucosa than in corresponding polyp or CRC lesions. JCV non-coding control region (NCCR) DNA rearrangements increased in CRC patients, also in normal mucosa, thus before the onset of the lesion. A new ∆98bp NCCR DNA rearrangement was detected. T-Ag levels were higher in normal mucosa than in adenoma and adenocarcinoma lesions, but decreased to levels of controls in established CRC lesions. In CRC, miR-J1-5p expression decreased with CRC progression. Vp1 expression was not detected. The data indicate a JCV link with the disease, but possible JCV contributes to oncogenesis should occur at pre-polyp stages.

Human endogenous retroviruses (HERVs) are genetic parasites, in-between genetics and environment. Few HERVs retain some coding capability. Sometimes, the host has the advantage of some HERV genes; conversely, HERVs may contribute to pathogenesis. The expression of HERVs depends on several factors, and is regulated epigenetically by stimuli such as inflammation, viral and microbial infections, etc. Increased expression of HERVs occurs in physiological and pathological conditions, in one or more body sites. Several diseases have been attributed to one or more HERVs, particularly neurological diseases. The key problem is to differentiate the expression of a HERV as cause or effect of a disease. To be used as a biomarker, a correlation between the expression of a certain HERV and the disease onset and/or behavior must be found. The greater challenge is to establish a pathogenic role. The criteria defining causal connections between HERVs and diseases include the development of animal models, and disease modulation in humans, by anti-HERV therapeutic antibody. So far, statistically significant correlations between HERVs and diseases have been achieved for HERV-W and multiple sclerosis; disease reproduction in transgenic animals was achieved for HERV-W and multiple sclerosis, and for HERV-K and amyotrophic lateral sclerosis. Clinical trials for both diseases are in progress.

Colorectal cancer (CRC) is a leading cause of cancer death worldwide and about 20% is metastatic at diagnosis and untreatable. The anti-EGFR therapy in metastatic patients is led by the presence of KRAS-mutations in tumor tissue. KRAS-wild-type CRC patients showed a positive response rate of about 70% to cetuximab or panitumumab combined with chemotherapy. MiRNAs are promising markers in oncology and could improve our knowledge on pathogenesis and drug resistance in CRC patients. This class of molecules represents an opportunity for the development of miRNA-based strategies to overcome the ineffectiveness of anti-EGFR therapy. We performed an integrative analysis of miRNA expression profile between KRAS-mutated CRC and KRAS-wildtype CRC and paired normal colic tissue (NCT). We revealed an overexpression of miR-425-5p in KRAS-mutated CRC compared to KRAS-wild type CRC and NCT and demonstrated that miR-425-5p exerts regulatory effects on target genes involved in cellular proliferation, migration, invasion, apoptosis molecular networks. These epigenetic mechanisms could be responsible of the strong aggressiveness of KRAS-mutated CRC compared to KRAS-wildtype CRC. We proved that some miR-425-5p targeted genes are involved in EGFR tyrosine kinase inhibitor resistance pathway, suggesting that therapies based on miR-425-5p may have strong potential in targeting KRAS-driven CRC. Moreover, we demonstrated a role in the oncogenesis of miR-31-5p, miR-625-5p and miR-579 by comparing CRC versus NCT. Our results underlined that miR-425-5p might act as an oncogene to participate in the pathogenesis of KRAS-mutated CRC and contribute to increase the aggressiveness of this subcategory of CRC, controlling a complex molecular network.

The human endogenous retrovirus (HERV)-K, human mouse mammary tumor virus like-2 (HML-2) subgroup of HERVs is activated in several tumors and has been related to prostate cancer progression and motor neuron diseases. The cellular splicing factor 2/alternative splicing factor (SF2/ASF) is a positive regulator of gene expression, coded by a potent proto-oncogene, amplified, and abnormally expressed in tumors. TAR DNA-binding protein-43 (TDP-43) is a DNA/RNA-binding protein, negative regulator of alternative splicing, known for causing neurodegeneration, and with complex roles in oncogenesis. We used the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology, with the Cas9 system from Staphylococcus aureus (SaCas9), to disrupt the HERV-K(HML-2)env gene, and evaluated the effects on cultured cells. The tool was tested on human prostate cancer LNCaP cells, whose HERV-Kenv transcription profile is known. It caused HERV-K(HML-2)env disruption (the first reported of a HERV gene), as evaluated by DNA sequencing, and inhibition of env transcripts and proteins. The HERV-K(HML-2)env disruption was found to interfere with important regulators of cell expression and proliferation, involved in manaling, RNA-binding, and alternative splicing, such as epidermal growth factor receptor (EGF-R), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), SF2/ASF, and TDP-43. These novel findings suggest that HERV-K is not an innocent bystander, they reinforce its links to oncogenesis and motor neuron diseases, and they open potential innovative therapeutic options.

The causes of multiple sclerosis and amyotrophic lateral sclerosis have long remained elusive. A new category of pathogenic components, normally dormant within human genomes, has been identified: human endogenous retroviruses (HERVs). These represent ∼8% of the human genome, and environmental factors have reproducibly been shown to trigger their expression. The resulting production of envelope (Env) proteins from HERV-W and HERV-K appears to engage pathophysiological pathways leading to the pathognomonic features of MS and ALS, respectively. Pathogenic HERV elements may thus provide a missing link in understanding these complex diseases. Moreover, their neutralization may represent a promising strategy to establish novel and more powerful therapeutic approaches., Highlights HERVs, retroviral sequences integrated into the genome during evolution, are now known to represent 8% of the human genome. These were recently shown to comprise copies that retain potential to express retroviral proteins or particles, and can be abnormally expressed in autoimmune, neurodegenerative, chronic inflammatory diseases, and cancer. Environmental factors such as specific viral infections were shown to potently activate HERVs under tissue-specific and temporal conditions. Of several diseases in which abnormal activation and expression of HERV proteins have been reported, studies over recent decades have led to a proof of concept that HERVs play a key role in the pathogenesis of MS and ALS. HERV-W and HERV-K Env proteins induce pathogenic effects in vitro and in vivo that are relevant to the pathognomonic features of these diseases. These endogenous retroviruses are potential novel therapeutic targets that are now being addressed with innovative therapeutic strategies in clinical trials.

Two human endogenous retroviruses of the HERV-W family are proposed as multiple sclerosis (MS) co-factors: MS-associated retrovirus (MSRV) and ERVWE1, whose env proteins showed several potentially neuropathogenic features, in vitro and in animal models. Phase II clinical trials against HERV-Wenv are ongoing. HERV-W/MSRV was repeatedly found in MS patients, in striking parallel with MS stages, active/remission phases, and therapy outcome. The HERV-Wenv protein is highly expressed in active MS plaques. Early MSRV presence in spinal fluids predicted worst MS progression 10 years in advance. Effective anti-MS therapies strongly reduced MSRV/Syncytin-1/HERV-W expression. The Epstein–Barr virus (EBV) activates HERV-W/MSRV in vitro and in vivo, in patients with infectious mononucleosis and controls with high anti-EBNA1-IgG titers. Thus, the two main EBV/MS links (infectious mononucleosis and high anti-EBNA1-IgG titers) are paralleled by activation of HERV-W/MSRV. It is hypothesized that EBV may act as initial trigger of future MS, years later, by activating MSRV, which would act as direct neuropathogenic effector, before and during MS.

The human genome contains remnants of ancestral retroviruses now endogenously transmitted, called human endogenous retroviruses (HERVs). HERVs can be variably expressed, and both beneficial and detrimental effects have described. This review focuses on the MSRV and syncytin-1 HERV-W elements in relationship to neurodegeneration in view of their neuro-pathogenic and immune-pathogenic properties. Multiple sclerosis (MS) and a neurodegenerative disease (neuroAIDS) are reported in this review. In vivo studies in patients and controls for molecular epidemiology and follow-up studies are reviewed, along with in vitro cellular studies of the effects of treatments and of molecular mechanisms. HERV-W/MSRV has been repeatedly found in MS patients (in blood, spinal fluid, and brain samples), and MRSV presence/load strikingly parallels MS stages and active/remission phases, as well as therapy outcome. The DNA of MS patients has increased MSRVenv copies, while syncytin-1 copies are unchanged in controls. Presence of MSRV in the spinal fluid predicted the worst MS progression, ten years in advance. The Epstein-Barr virus (EBV) activates HERV-W/MSRV both in vitro and in vivo. With respect to neuroAIDS, the HIV transactivator of transcription (Tat) protein activates HERV-W/MSRV in monocytes/macrophages and astrocytes indirectly by interaction with TLR4 and induction of TNFa. HERV-W/MSRV can be considered a biomarker for MS behavior and therapy outcome. Regarding MS pathogenesis, we postulate the possibility for EBV of an initial trigger of future MS, years later, and for MSRV of a direct role of effector of neuropathogenesis during MS. Additionally, HERV-W/MSR/syncytin-1 activation by HIV Tat could contribute to the HIV-related neurodegeneration.

Human astrocyte cells were exposed to HIV-Tat and/or epidermal growth factor (EGF), to monitor the expression of the neuropathogenic MSRV and Syncytin-1 elements of the HERV-W family of endogenous retroviruses and of TNFα. The results indicate that EGF counteracts Tat regulation of HERV-W/MSRVenv/Syncytin-1, throughout EGFR activation; this effect occurs by interfering with the induction of TNFα production by Tat. The novel effect of EGF counteraction of Tat-mediated regulation of the neuropathogenic HERV-Ws could be neuro-protective, but its actual role in the brain remains to be elucidated.

OBJECTIVE 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. DESIGN AND METHODS 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. RESULTS 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. CONCLUSION 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.

Interferons (IFN) are key cytokines with multifaceted antiviral and cell-modulatory properties. Three distinct types of IFN are recognized (I-III) based on structural features, receptor usage, cellular source and biological activities. The action of IFNs is mediated by a complex, partially overlapping, transcriptional program initiated by the interaction with specific receptors. Genetic diversity, with polymorphisms and mutations, can modulate the extent of IFN responses and the susceptibility to infections. Almost all viruses developed mechanisms to subvert the IFN response, involving both IFN induction and effector mechanisms. Interactions between IFN types may occur, for both antiviral and cell-modulatory effects, in a complex interplay, involving both synergistic and antagonistic effects. Interferon-associated diseases, not related to virus infections may occur, some of them frequently observed in IFN-treated patients. On the whole, IFNs are pleiotropic biologic response modifiers, that, upon activation of thousands genes, induce a broad spectrum of activities, regulating cell cycle, differentiation, plasma membrane molecules, release of mediators, etc., that can be relevant for cell proliferation, innate and adaptive immunity, hematopoiesis, angiogenesis and other body functions.

Natalizumab is effective against multiple sclerosis (MS), but is associated with progressive multifocal leukoencephalopathy (PML), fatal disease caused by the JCV polyomavirus. The SF2/ASF (splicing factor2/alternative splicing factor) inhibits JCV in glial cells. We wondered about SF2/ASF modulation in the blood of natalizumab-treated patients and if this could influence JCV reactivation. Therefore, we performed a longitudinal study of MS patients under natalizumab, in comparison to patients under fingolimod and to healthy blood donors. Blood samples were collected at time intervals. The expression of SF2/ASF and the presence and expression of JCV in PBMC were analyzed. A bell-shaped regulation of SF2/ASF was observed in patients treated with natalizumab, increased in the first year of therapy, and reduced in the second one, while slightly changed, if any, in patients under fingolimod. Notably, SF2/ASF was up-regulated, during the first year, only in JCV DNA-positive patients, or with high anti-JCV antibody response; the expression of the JCV T-Ag protein in circulating B cells was inversely related to SF2/ASF protein expression. The SF2/ASF reduction, parallel to JCV activation, during the second year of therapy with natalizumab, but not with fingolimod, may help explain the increased risk of PML after the second year of treatment with natalizumab, but not with fingolimod. We propose that SF2/ASF has a protective role against JCV reactivation in MS patients. This study suggests new markers of disease behavior and, possibly, help in re-evaluations of therapy protocols.

International audience; The First International Scientific Conference on Human Endogenous Retroviruses (HERVs) and Disease, Lyon-France, May 26-27th 2015, brought together scientific and medical specialists from around the world investigating the involvement of human endogenous retroviruses (HERVs) in complex human diseases.

The human neurotropic polyomavirus JC (JCV) induces a broad range of neural-origin tumors in experimental animals and has been repeatedly detected in several human cancers, most notably neural crest–origin tumors including medulloblastomas and glioblastomas. The oncogenic activity of JCV is attributed to the viral early gene products, large T and small t antigens, as evident by results from in vitro cell culture and in vivo animal studies. Recently, we have shown that alternative splicing factor, SF2/ASF, has the capacity to exert a negative effect on transcription and splicing of JCV genes in glial cells through direct association with a specific DNA motif within the viral promoter region. Here, we demonstrate that SF2/ASF suppresses large T antigen expression in JCV-transformed tumor cell lines, and the expression of SF2/ASF in such tumor cells thereby inhibits the transforming capacity of the viral tumor antigens. Moreover, down-regulation of SF2/ASF in viral-transformed tumor cell lines induces growth and proliferation of the tumor cells. Mapping analysis of the minimal peptide domain of SF2/ASF responsible for JCV promoter silencing and tumor suppressor activity suggests that amino acid residues 76 to 100 of SF2/ASF are functionally sufficient to suppress the growth of the tumor cells. These observations demonstrate a role for SF2/ASF in JCV-mediated cellular transformation and provide a new avenue of research to pathogenic mechanisms of JCV-induced tumors.

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). MSRVenv and syncytin-1 are closely related, and difficult to distinguish each other. The sequences of extracellular MSRVenv 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, MSRVenv 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 MSRVenv 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 MSRVenv 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 MSRVenv 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.

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.

The newly discovered type III interferon lambda (IFN-lambda) has antiviral activity against a broad spectrum of viruses and potent immune-related activities. Its major producers are peripheral blood mononuclear cells (PBMCs) and dendritic cells. The above functions and cells are deeply involved in AIDS pathogenesis, but there is no information so far on IFN-lambda effects on HIV. Therefore we addressed the sensitivity of HIV-1 replication to cell exposure to human IFN-lambda2. Human PBMCs and C8166 T cells were treated with human Type III or Type I IFNs, and the ability of HIV-1 to bind and replicate in untreated and IFN-treated cells was investigated. Virus amounts were quantified by infectivity and p24 assays. In parallel, we evaluated the possible antiproliferative effects of IFN-lambda2 and the expression of CD4, CXCR4, and CCR5 genes, whose transcripts were quantified by real time RT-PCR. Data showed increased adsorption of HIV to IFN-treated cells in a dose-dependent fashion. Virus yields increased accordingly. In both systems the accumulation of CD4, CXCR4, and CCR5 transcripts was increased, particularly in PBMCs. Antiproliferative activity and classical antiviral state were instead detected on PBMCs, but not on C8166 cells. We concluded that pretreatment of PBMCs and C8166 cells with Type III and Type I IFNs causes increased HIV binding and replication. These effects are likely to be due to increased expression of HIV receptors and coreceptors on the plasma membrane. These findings indicate another mechanism utilized by HIV for subversion of host defenses.

Transcriptional regulation of the human immunodeficiency virus type 1 (HIV-1) is a complex event that requires the cooperative action of both viral (e.g. Tat) and cellular (e.g. C/EBPβ, NF-κB) factors. The HIV-1 Tat protein recruits the human positive transcription elongation factor P-TEFb, consisting of cdk9 and cyclin T1, to the HIV-1 transactivation response (TAR) region. In the absence of TAR, Tat activates the HIV-1 long terminal repeat (LTR) through its association with several cellular factors including C/EBPβ. C/EBPβ is a member of the CCAAT/enhancer-binding protein family of transcription factors and has been shown to be a critical transcriptional regulator of HIV-1 LTR. We examined whether Tat–C/EBPβ association requires the presence of the P-TEFb complex. Using immunoprecipitation followed by Western blot, we demonstrated that C/EBPβ–cyclin T1 association requires the presence of cdk9. Further, due to its instability, cdk9 was unable to physically interact with C/EBPβ in the absence of cyclin T1 or Tat. Using kinase assays, we demonstrated that cdk9, but not a cdk9 dominant-negative mutant (cdk9-dn), phosphorylates C/EBPβ. Our functional data show that co-transfection of C/EBPβ and cdk9 leads to an increase in HIV-1 gene expression when compared to C/EBPβ alone. Addition of C/EBP homologous protein (CHOP) inhibits C/EBPβ transcriptional activity in the presence and absence of cdk9 and causes a delay in HIV-1 replication in T-cells. Together, our data suggest that Tat–C/EBPβ association is mediated through cdk9, and that phosphorylated C/EBPβ may influence AIDS progression by increasing expression of HIV-1 genes.

Several lines of evidence indicate a genetic contribution to multiple sclerosis (MS) both in terms of predisposition to the disease and of immunological mechanisms which are known to play crucial roles in MS pathogenesis. The presence of high- and low-risk areas for MS in neighbouring regions supports the theory that MS predisposition is influenced by a complex interaction of genetic and environmental factors. Therefore, the use of genetically homogeneous and geographically isolated populations becomes an increasing requirement to reduce biasing biological variables. Sardinians fulfil these conditions well because of their different phylogeny from Europeans and the unique selective pressures which shaped their genome. Sardinians display amongst the highest MS prevalence rates world-wide and increasing MS incidence rates over time. Also, MS in Sardinia is linked to distinct human leucocyte antigen (HLA) alleles and associated to different patterns of cytokine production from lymphoid cells of different HLA subtypes. In this context, recent findings and future perspectives on the peculiarities of Sardinian MS concerning genetic, immunological and epidemiological aspects are presented. So far, our results indicate that variations at the level of territorial distribution and HLA-association are present which render MS heterogeneous even in this ethnically homogeneous population.

HIV-E, emerging from persistently infected HeLa-T4 cells, replicates better in fibroblasts and epithelial cells with respect to the parental, T cell-derived HIV-T. The two viruses share the same env V3 loop, but differ in cellular molecules incorporated on the envelope. Even when similar amounts of virus attachment occurred, HIV-E replicated better than HIV-T in cells from solid tissues, and the response to exogenous Tat was more efficient. This might be related to the long terminal repeat (LTR), because HIV-E has a TAR duplication, and a mutation in the Sp1-II binding site. Epithelial cells deserve further study, because they may be important in vivo for variant selection and latency.

The recent literature review published in the Journal of Neuroimmunology by Hon et al . (2013) concerning multiple sclerosis associated retrovirus (MSRV) and human endogenous retrovirus-W (HERV-W) in patients with multiple sclerosis contains a number of errors and a fundamental logical misconception. We consider that we should bring this to the readers' attention in order to avoid misinterpretation of the current literature. One of the search terms used by Hon et al ., to conduct the literature search, was “MSRW/HERV-W”. Use of this search term will fail to locate articles because the correct abbreviation is MSRV, not MSRW. The authors incorrectly state that Arru et al . (2007) reported detection of MSRV pol sequences in the cerebrospinal fluid (CSF) of 40% of healthy controls. The 40% figure in Arru et al . actually refers to the prevalence of MSRV pol sequences in patients with other neurological diseases (OND) rather than in healthy controls, in whom the prevalence was much lower. As reviewed by Dolei and Perron (2009), the presence/load of extracellular MSRV was found increased repeatedly and independently in the blood and CSF of MS cohorts (prevalence in plasma, 53%–100%) of Caucasians from France, Sardinia, Northern Italy, Poland, Sweden, Spain and South Africa. MSRV viraemia also occurred in OND patients, but the frequency of MSRV detection was significantly lower than in MS, and MSRV load was significantly associated with MS in all ethnic groups studied; as for healthy controls, a meta-analysis from six independent studies showed that a mean of 8.9% ± 6.2% of Caucasian blood donors had circulating virionic MSRV/HERV-W RNA. At several places in the text, including the last sentence of the Abstract and the concluding sentence of the review, Hon et al . state that because MSRV/HERV-W expression is not completely restricted to patients with MS, it is “therefore an unlikely cause of the disease”. Indeed, this appears to be the major conclusion of the review. In our opinion, this conclusion is over-simplistic and clearly represents a logical non sequitur. If, as Hon et al . appear to believe, it were true that detection of an agent in a proportion of the healthy population meant that the agent was not or was unlikely to be the cause of disease, then we would have to dismiss many well established pathogens and the entire concept of asymptomatic infection. The human retrovirus HTLV-1 for example causes disease (adult T-cell leukemia/lymphoma or HTLV-I-associated myelopathy) in only a small proportion of those infected and the vast majority remain lifelong asymptomatic carriers (Goncalves et al ., 2010). Similarly, a significant proportion of healthy individuals are carriers of methicillin resistant Staphylococcus aureus (MRSA), a pathogen well known to be capable of causing life-threatening sepsis ( Stefani et al ., 2012). Environmental risk factors provide many other illustrations of this false logic; smoking is an incontrovertible cause of lung cancer and yet smoking is prevalent in a significant proportion of the healthy population. The majority of the studies reviewed by Hon et al. provide evidence of an association between MSRV/HERV-W expression and multiple sclerosis, but they were not intended to prove causality. Young et al . (2013) have recently discussed the criteria required to establish causal connections between HERVs and disease. These include the development of animal models and attempts to modulate disease in man by blocking endogenous retroviral protein function with therapeutic antibody; both of these criteria are currently being addressed for MSRV ( Curtin et al ., 2012 and Perron et al ., 2013). The potential contribution of co-factors such as Epstein–Barr virus (EBV), which are known to activate MSRV/HERV-W, should also be considered in this context ( Mameli et al ., 2012 and Mameli et al ., 2013).

Background: Several viruses were reported as co-factors triggering the pathogenesis of multiple sclerosis (MS), including the endogenous retroviruses of the HERV-W family, that were also proposed as biomarkers of disease progression and therapy outcome. Objective: The objective of this article is to clarify whether in MS patients treatment with natalizumab has effects on MSRV/syncytin-1/HERV-W expression and the possible relationship with disease outcome. Methods: Peripheral blood mononuclear cells were collected from 22 patients with relapsing–remitting disease, at entry and after three, six and 12 months of treatment with natalizumab. The cell subpopulations and the expression of MSRV env/syncytin-1/HERV-W env were analyzed by flow cytometry and by discriminatory env-specific RT-PCR assays. Results: By flow cytometry the relative amounts of T, NK and monocyte subpopulations were shown to remain fairly constant. A relative increase of B lymphocytes was observed at three to six months ( p = 0.033). The MSRV env and syncitin-1 transcripts were reduced at six to 12 months of therapy ( p = 0.0001). Accordingly, at month 12, the plasma-membrane levels of the HERV-W env protein were reduced ( p = 0.0001). B cells, NK and monocytes but not T cells expressed the HERV-W env protein. None of the patients relapsed during therapy. Conclusion: Effective therapy with natalizumab downregulates MSRV/syncytin-1/HERV-W expression.

BK and JC polyomaviruses (BKV and JCV) are widespread in humans and are thought to persist and reactivate under immune alterations. In addition to the kidney, lymphoid cells have been proposed as a site of latency. However, while this was shown to occur in immunocompromised patients, discordant data were published for healthy humans. To help to solve this issue, an extensive study (231 healthy subjects) was carried out on peripheral blood mononuclear cells (PBMC) from blood donors of two towns and from operators of a blood transfusion centre. To discriminate between past and recent infection, nested PCRs for BKV and JCV non-coding control region (NCCR) and VP1 DNA sequences were carried out. Twenty-two per cent of subjects had BKV NCCR, but only 7% also had BKV VP1, as detected by PCR assays of similar sensitivities; the latter positivity was found to decrease with age. In both towns, the BKV WW archetypal DDP strain, subtype I, was found. Only 0·9% of subjects contained JCV DNA, for both NCCR and VP1. Blood operators presented a statistically significant increased prevalence of BKV NCCR (3·0-fold) and BKV VP1 (9·4-fold) sequences with respect to blood donors of comparable ages, suggesting the possibility of occupational risk of BKV (re)infection or reactivation. Since the possibility of amplifying BKV VP1 sequences from PBMC of healthy humans is lost with age, this suggests that PBMC are not a site of polyomavirus persistence in healthy individuals and that detection of BKV VP1 DNA in PBMC is probably indicative of recent infection or reactivation.

The beta-chemokines RANTES, MIP-1alpha, and MIP-1beta have been shown to inhibit the infection of T cells by macrophage-tropic HIV-1 strains by blocking env-driven HIV-1 fusion through competition for the chemokine receptors or receptor downregulation. This study was aimed at testing whether beta-chemokines also inhibit the productive infection of monocyte-derived macrophages (MDMs) by a monocytotropic HIV-1 strain, by using virus yield assays. The action of the beta-chemokines MIP-1alpha, MIP-1beta, and RANTES was captured with that of the alpha-chemokine interleukin 8 (IL-8) and of interferon alpha (IFN-alpha), which is a well-known broad-range inhibitor of viral replication. While IL-8 did not inhibit HIV-1 BaL replication in MDMs, the beta-chemokines were dose-dependently inhibitory. RANTES was the most effective, reaching at 300 ng/ml a protection similar to that obtained with IFN-alpha at 1000 IU/ml, and was even more inhibitory when added to MDMs after virus attachment. In contrast to IFN-alpha, the antiviral activity of beta-chemokines was restricted to HIV, because another virus was not inhibited. As compared with untreated MDMs, full-length proviral DNA at day 1 postinfection was inhibited in MDMs treated with RANTES either before or after the absorption phase, and even more so in IFN-treated MDMs, whereas in IL-8-treated MDMs no inhibition was observed. Our results indicate that in MDMs both RANTES and IFN affect early steps of HIV-1 BaL replication, preceding the completion of viral DNA synthesis.

Objective and design To study, in T-lymphoid cells, the effects of macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES beta-chemokines on the replication of T-cell-tropic HIV-1 strains, since it has been reported that beta-chemokines interfere with the replication of macrophage-tropic HIV-1 strains, but not T-cell-tropic strains. Methods Freshly phytohaemagglutinin (PHA)-activated peripheral blood lymphocytes (PBL) and cultured PHA-activated T cells from healthy volunteers, as well as the C8166 T-cell line, were treated overnight with beta-chemokines before infection with T-cell-tropic HIV-1 isolates, or human T-lymphotropic virus type IIIB. HIV replication was followed by detecting the production of infectious particles, p24 antigen, and viral sequences. CXC-chemokine receptor (CXCR)-4 expression was followed by detection and quantification of specific transcripts. Results Pretreatment of T cells with MIP-1alpha, MIP-1beta and RANTES affected T-cell-tropic strains, increased the replication of HIV-1beta and HIV-1RPdT strains dose-dependently, as well as virus absorption and provirus DNA accumulation. These findings were associated with increased accumulation of CXCR-4 transcripts, and mediated by the protein tyrosine kinase signalling. Moreover, beta-chemokines stimulated PBL proliferation. Conclusions Beta-chemokines increase the adsorption and replication of at least some T-cell-tropic HIV-1 strains, and this is related to stimulated expression of the CXCR-4 coreceptor.

We designed a large multicentric study to analyse the presence of MSRV particles in blood and CSF of a large cohort of patients and controls from different European areas. 149 MS patients and 153 neurological and healthy controls were selected from Sardinia, Spain, Northern-Italy and Sweden. To avoid biological and inter-assay variability MSRV was detected within a single laboratory through nested and real-time PCR assays specific for pol and env genes. MSRV detection in blood and CSF of MS patients and controls in populations of different ethnicity gave significant differences (p

HIV-1 is a polytropic virus that, apart from hematopoietic cells, can replicate in several cells from solid tissues. Virus yields vary widely, closely resembling differences in HIV binding to the cells; the latter phenomenon appears mainly related to the extent of CD4 expression, even though other molecules have been implied in virus-cell interactions, the expression of which on the cell membrane can be modulated by several stimuli. During the course of HIV replication, a series of cytokines is produced and released in parallel to virus growth, particularly IL-6 and TNF-α. In fact, exposure of fibroblasts or epithelial cells to these HIV-in-duced cytokines causes an increase of CD4 expression, HIV adsorption to uninfected cells, and release of infectious virions by infected cells. In cells exposed to interferon-γ, IL-6 and TNF-α allow the virus to bypass interferon inhibition of virus release. The fact that HIV-1 adsorption and spread can be mediated by HIV-induced cytokines may be relevant in AIDS pathogenesis, accelerating virus transmission both within the organ and to infiltrating cells, activating a self-maintaining mechanism of infection.

Vascular endothelial cells (EC) play a key role in viral tropism in vivo. Since conflicting reports have been published on the capability of HIV to infect EC in vitro, we analyzed some factors potentially capable of influencing the susceptibility of human umbilical vein endothelial cells (HUVEC) to HIV-1. Both primary cultures and differentiated immortalized HUVEC lines were used. HUVEC were negative for the expression of CD4, but weakly CD26- and galactosylceramide-positive. Although binding of HIV to EC was substantial, the virus was apparently incapable of replicating in nonproliferating cultures. In resting cultures, the content of cell-associated HIV disappeared 4-6 days after infection without production of p24 and infectious progency. In contrast, infection of proliferating EC cultures led to the transient release of p24 and infectious virus (10(2.5)-10(3.5) SFU/ml) peaking 2-6 days postinfection. Antibody neutralization of cytokines that may be produced by EC (IL1, IL6, IL8, TNF, IFN-beta) failed to modify virus adsorption and replication, whereas treatment with IL1-beta plus TNF-alpha stimulated both virus binding and virus release. As seen by gag polymerase chain reaction (PCR), the viral genome persisted up to 15 days in untreated EC cultures, but over 20 days in cultures exposed to IL1-beta plus TNF-alpha. This study shows that: (a) CD4-negative HUVEC are capable of binding substantial amounts of HIV-1; (b) binding is enhanced by proinflammatory cytokines; (c) the establishment of productive infection is favored by cell proliferation; and (d) exposure to IL1-beta plus TNF-alpha enhances virus replication.

Objective and design : To determine the susceptibility of mammary epithelial cells (MEC) to HIV-1 as breastfeeding is an established route of HIV transmission, although the origin of virus in breastmilk is unclear. Methods : Primary epithelial cell cultures were derived from the mammary glands of healthy donors ; immortalized MEC lines were also used. HIV infection was followed by detection of infectious particle production, p24 antigen and viral sequences. Results : Seven out of 11 primary MEC cultures and two out of three MEC lines were productively infected by HIV-1. Virus replication significantly reduced cell proliferation, although cell viability was only slightly affected. Cytopathic changes were not observed. MEC cultures expressed low levels of surface CD4, galactosylceramide and CD26, but essentially no human leukocyte antigen (HLA)-DR. Infection of HIV-permissive MEC cells was associated with the upregulation of surface HLA-DR and CD26. In contrast, the expression of CD4, tissue-specific markers, adhesion molecules and growth-factor receptors was downregulated. To a lesser extent, similar effects were also observed in non-permissive cells. Hormones (triiodothyronine plus β-estradiol and prolactin) enhanced HIV replication, possibly through the stimulation of cellular DNA synthesis. Conclusions : We concluded that HIV-1 replication in ductal/alveolar MEC may be, in part, responsible for the presence of HIV-1 in milk ; that hormones may stimulate virus replication ; and that infection reduces the growth of epithelial cells. Although in vitro HIV is produced by MEC to a lesser extent than lymphoid cells, MEC-derived HIV might have selective advantages for the infection of mucosal epithelial cells during breastfeeding.

Background: Proposed 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 Findings: In 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-kB 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.

We asked whether HIV-1 had the capacity to establish a persistent infection of cultured human diploid fibroblasts. Human strains of normal diploid embryo lung fibroblasts were infected with HIV-1 of the HTLV-IIIB and HIV-1P1 strains. Infection was followed over time, to analyze HIV expression. Virus production (intra- and extracellular virus) was evaluated as follows: ability to form syncytia in the C8166 T cell line, production of p24 and other viral antigens (ELISA and indirect immunofluorescence), search for a gag sequence in cell DNA by the polymerase chain reaction followed by hybridization to an HIV-1-specific probe (SK19). Cell-free culture supernatant was used as a virus source to infect de novo fibroblasts and C8166 T cells. Infection of cultured fibroblasts with either the HTLV-IIIB or HIV-1P1 strain led regularly to the establishment of persistently infected cultures. Fibroblast cells were capable of continuous virus production for at least 10 months. The released virus was capable of reinfecting cultured fibroblasts and of producing cytopathic effects in the C8166 T cell line. However, when compared to wild-type strains, the infectious virus derived from fibroblasts showed a prolonged replication cycle and a decreased ability to form syncytia in the T cell line. Therefore, HIV-1 can establish a persistent and productive infection in normal lung fibroblasts. The data are consistent with the hypothesis that in vivo, at least in the lung, fibroblasts may represent a virus reservoir and that infection of these cells may lead to the production of attenuated variants of HIV.

Retrovirus-like particles containing the multiple sclerosis-associated retrovirus RNA, significantly found in the cerebrospinal fluid of patients with multiple sclerosis, have been preliminarily associated with a short-term poor clinical and radiological prognosis of the disease. We asked whether these prognostic indications are still measurable after a long-term clinical evaluation (10 years). Our 10-year blind observational study confirms that the presence of multiple sclerosis-associated retrovirus in the cerebrospinal fluid of early multiple sclerosis patients is associated with a significantly greater rate of relapse-unrelated unremitting disability and secondary progression of the disease.

Human endogenous retroviruses (HERVs) constitute up to 8% of the human genome. In general they are highly defective, but complete proviruses have also been described. Over time some transposable elements became inactive, while others retain mobility within the genome. Variably inserting in cellular genes, and differentially within the various allotypes of polymorphic genes, they may have determined inheritable, stable gene modifications. Approximately 40,000 HERV elements have been identified to date, including truncated and solitary long terminal repeats. The latter have powerful transcriptional regulatory properties, therefore they may behave as promoters and enhancers of cellular genes and interact with oncogenes. In some cases, the host has utilized the presence of these ancestrally transmitted foreign genomes to serve physiological functions, and several possible beneficial effects have been reported. On the other hand, links of some human diseases with HERVs are increasingly observed, and this review presents data on possible HERV association to human disease. Reports have shown expression of one or more HERVs in physiological or pathological conditions, in one or more body sites. A key problem is differentiating this expression as cause or effect of a particular disease. Human diseases have been related to HERVs, particularly those characterized by multifactorial etiology or dysregulated immune functions, such as multiple sclerosis, Type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, psoriasis, schizophrenia, cancer and hematological disorders. Convincing evidence has been found that the HERV-W family has a physiological role in early pregnancy and a role in multiple sclerosis as a cofactor and predictor of disease progression. Data available for HERVs and other diseases are attractive, but further studies are required.

Low levels of anti-viral activity, mainly interferon alpha/beta (IFN-alpha/beta), are regularly found in lymphoid tissues of BALB/c mice infected with the C3H strain of mammary tumor virus. At the time of tumor development, significant amounts of anti-viral activity were detected in homogenates of spleen and mammary tumors, but not in blood and normal mammary glands. This activity is pH2-resistant and neutralized by antibody to IFN/alpha-beta. The pathogenetic role of IFN in mammary carcinogenesis was investigated in 2 ways: (a) by treating virus-infected newborn mice with antibody to IFN-alpha/beta, and (b) by giving either the latter antibody or IFN-alpha/beta to virus-free animals transplanted with pre-neoplastic lesions. Mice were treated only for 2 months, starting either 1 week after birth or immediately after tumor transplant. In case (a), treatment with antibody to IFN-alpha/beta shortened the incubation period of mammary carcinomas and decreased the mean survival time. In case (b), anti-IFN antibody did not significantly affect the development of mammary tumors. However, exogenous IFN-alpha/beta markedly reduced both tumor incidence and mortality rate. These results indicate that endogenous IFN-alpha/beta plays a crucial role in the in vivo restriction of the early infectious phase of spontaneous carcinogenesis and that relatively high doses of IFN-alpha/beta may inhibit the progression of pre-neoplastic lesions.

Spontaneously immortalized human mammary epithelial cells MCF-10A were transfected with an activated c-Ha-ras oncogene. Transfected cells (MCF-10T) acquire a malignant phenotype, as already reported. Studies of 125I-2'-deoxyuridine incorporation in cultures given graded doses of hydrocortisone (HC), cholera toxin (CT), epidermal growth factor (EGF), and transforming growth factor alpha (TGF-alpha) showed that though MCF-10T had become almost independent on exogenous EGF and TGF-alpha, they continued to respond to the synergistic effect of HC and CT plus EGF. Both lines were phenotypically characterized with an immunoradiometric assay in live cells. Expression of MHC class-I molecules, human milk-fat-globule-I antigen, and EGF receptor was reduced in ras-transfected cells, although other differentiation markers were unchanged. Exogenous EGF down-regulated the expression of functional EGF-R, selectively in transformed cells. TGF-alpha failed to modulate EGF-R. In contrast, HC strongly stimulated the expression of EGF-R while depressing MHC class-I molecules. Thus, it appears that in vivo HC may co-operate with TGF-alpha and EGF in promoting the growth of transformed mammary cells. This hormone might also favor the escape from immune surveillance by reducing the expression of surface differentiation markers.

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.

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.

Syncytin-1 has a physiological role during early pregnancy, as mediator of trophoblast fusion into the syncytiotrophoblast layer, hence allowing embryo implantation. In addition, its expression in nerve tissue has been proposed to contribute to the pathogenesis of multiple sclerosis (MS). Syncytin-1 is the env glycoprotein of the ERVWE1 component of the W family of human endogenous retroviruses (HERV), located on chromosome 7q21-22, in a candidate region for genetic susceptibility to MS. The mechanisms of ERVWE1 regulation in nerve tissue remain to be identified. Since there are correlations between some cytokines and MS outcome, we examined the regulation of the syncytin-1 promoter by MS-related cytokines in human U-87MG astrocytic cells. Using transient transfection assays, we observed that the MS-detrimental cytokines TNFalpha, interferon-gamma, interleukin-6, and interleukin-1 activate the ERVWE1 promoter, while the MS-protective interferon-beta is inhibitory. The effects of cytokines are reduced by the deletion of the cellular enhancer domain of the promoter that contains binding sites for several transcription factors. In particular, we found that TNFalpha had the ability to activate the ERVWE1 promoter through an NF-kappaB-responsive element located within the enhancer domain of the promoter. Electrophoretic mobility shift and ChIP assays showed that TNFalpha enhances the binding of the p65 subunit of NF-kappaB, to its cognate site within the promoter. The effect of TNFalpha is abolished by siRNA directed against p65. Taken together, these results illustrate a role for p65 in regulating the ERVWE1 promoter and in TNFalpha-mediated induction of syncytin-1 in multiple sclerosis.

One prognostic factor for early multiple sclerosis (MS) patients to develop a definite MS may be the presence of the MS-associated retrovirus (MSRV) in the cerebrospinal fluid (CSF). We designed a specific study on a cohort of optic neuritis (ON) patients to evaluate the MSRV-dependent conversion to MS relative to the prediction conferred by magnetic resonance imaging (MRI) and CSF abnormalities. At follow-up, 33.3% MSRV+ and 0% MSRV- ON patients developed MS (P = 0.03). The prediction value is lower than that given by CSF and MRI abnormalities (42.3%). This intriguing finding is discussed in the light of the abundant discrepancies observed in the MSRV literature. Multiple Sclerosis 2006; 12: 357-359. www.multiplesclerosisjournal.com

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.

Syncytin is a protein specifically expressed in human placenta during early pregnancy, and found to be responsible for fusion of fetal trophoblast cells into the placental multinucleated syncytiotr...

HIV-E, emerging from persistently infected HeLa-T4 cells, replicates better in fibroblasts and epithelial cells with respect to the parental, T cell-derived HIV-T. The two viruses share the same env V3 loop, but differ in cellular molecules incorporated on the envelope. Even when similar amounts of virus attachment occurred, HIV-E replicated better than HIV-T in cells from solid tissues, and the response to exogenous Tat was more efficient. This might be related to the long terminal repeat (LTR), because HIV-E has a TAR duplication, and a mutation in the Sp1-II binding site. Epithelial cells deserve further study, because they may be important in vivo for variant selection and latency.

Blood and CSF of Sardinian patients with MS and neurologic control subjects were tested for MS-associated retrovirus (MSRV). CSF detection in MS was 50% at clinical onset, increasing with temporal disease progression, and 40% in control subjects. In blood, MSRV was detected in all MS patients, in most patients with inflammatory neurologic diseases, and rarely in healthy blood donors. MSRV may represent a marker of neurologic diseases of inflammatory origin.