Human endogenous retroviruses (HERVs) arise from ancient infections of the host germline cells by exogenous retroviruses, constituting 8% of the human genome. Elevated level of envelope transcripts from HERVs-W has been detected in CSF, plasma and brain tissues from patients with Multiple Sclerosis (MS), most of them from Xq22.3, 15q21.3, and 6q21 chromosomes. However, since the locus Xq22.3 (ERVWE2) lack the 5′ LTR promoter and the putative protein should be truncated due to a stop codon, we investigated the ERVWE2 genomic loci from 84 individuals, including MS patients with active HERV-W expression detected in PBMC. In addition, an automated search for promoter sequences in 20 kb nearby region of ERVWE2 reference sequence was performed. Several putative binding sites for cellular cofactors and enhancers were found, suggesting that transcription may occur via alternative promoters. However, ERVWE2 DNA sequencing of MS and healthy individuals revealed that all of them harbor a stop codon at site 39, undermining the expression of a full-length protein. Finally, since plaque formation in central nervous system (CNS) of MS patients is attributed to immunological mechanisms triggered by autoimmune attack against myelin, we also investigated the level of similarity between envelope protein and myelin oligodendrocyte glycoprotein (MOG). Comparison of the MOG to the envelope identified five retroviral regions similar to the Ig-like domain of MOG. Interestingly, one of them includes T and B cell epitopes, capable to induce T effector functions and circulating Abs in rats. In sum, although no DNA substitutions that would link ERVWE2 to the MS pathogeny was found, the similarity between the envelope protein to MOG extends the idea that ERVEW2 may be involved on the immunopathogenesis of MS, maybe facilitating the MOG recognizing by the immune system. Although awaiting experimental evidences, the data presented here may expand the scope of the endogenous retroviruses involvement on MS pathogenesis.

Natalizumab is currently one of the best options for treatment of patients with Multiple Sclerosis who have failed traditional prior therapies. However, prolonged use, prior immunosuppressive therapy and anti-JCV antibody status have been associated with increased risk of developing progressive multifocal leukoencephalopathy (PML). The evaluation of these conditions has been used to estimate risks of PML in these patients, and distinct (sometimes extreme) approaches are used to avoid the PML onset. At this time, the biggest issue facing the use of Natalizumab is how to get a balance between the risks and the benefits of the treatment. Hence, strategies for monitor JCV-positive patients undergoing Natalizumab treatment are deeply necessary. To illustrate it, we monitored JCV/DNA in blood and urine of a patient receiving Natalizumab for 12 months. We also bring to discussion the effectiveness of the current methods used for risk evaluation, and the real implications of viral reactivation.Keywords: multiple sclerosis, Natalizumab, JCV, risk factors, progressive multifocal leucoencephalopaty, viruria. RESUMO Natalizumabe é atualmente uma das melhores opções para o tratamento de pacientes com Esclerose Múltipla que não respondem aos tratamentos tradicionais. No entanto, o seu uso prolongado, o uso de terapia imunossupressora prévia e o status sorológico antivírus JC têm sido associados com o risco aumentado de desenvolvimento de Leucoencefalopatia Multifocal Progressiva (LEMP). A avaliação destas condições tem sido utilizada para estimar os riscos do desenvolvimento de LEMP nestes pacientes, e abordagens distintas (por vezes extremas) são empregadas para evitar o aparecimento dessa patologia. Atualmente, o grande desafio está em obter um equilíbrio entre os riscos e os benefícios do tratamento com Natalizumabe. Assim, é crucial desenvolver estratégias para monitorar pacientes portadores do vírus JC sob tratamento com Natalizumabe. A título de ilustração, pesquisamos o vírus no sangue e na urina de um paciente sob tratamento durante 12 meses. Também discutimos a eficácia dos métodos atualmente utilizados para avaliação de riscos e as implicações reais de reativação viral.Palavras-chave: esclerose múltipla, Natalizumabe, vírus JC, leucoencefalopatia multifocal progressiva, viruria. Natalizumab (Tysabri), used for treatment of relapsingremitting multiple sclerosis (MS), is a monoclonal antibody directed to the a4b1 integrin, a subunit of an adhesion molecule expressed on the surface of T lymphocytes. The antibodies act by blocking the migration of T Lymphocytes from blood to the CNS through the blood brain barrier (BBB) and attenuate the inflammatory effects 1 . The AFFIRM study showed that monotherapy with Natalizumab (NTZ) for 2 years decreased the relapse rate by 68% and the disability progression rate by 42% compared with placebo 2 . NTZ is well tolerated and the overall incidence of serious adverse events is low. Although the efficacy of NTZ is up to

Patients undergoing Natalizumab (NTZ) therapy are at risk of progressive multifocal leukoencephalopathy (PML). Besides John Cunningham virus (JCV), BK polyomavirus might represent an additional concern for such patients since it can also infect CNS cells. Currently, data regarding the presence of anti-JCV antibodies added to previous immunosuppressive therapy and prolonged NTZ therapy has been used to classify patients at risk of developing PML. Here, we investigated the profile shedding of JCV and BKV in multiple sclerosis (MS) patients during treatment with NTZ. Serial blood and urine samples from 97 MS patients receiving either NTZ or β-interferon were investigated for polyomavirus shedding. While all blood samples tested negative, 36% of the patients shed polyomavirus in the urine in at least one time point. From these, 21.7%, 9.3%, and 5.1% shed JCV, BKV, and both polyomavirus, respectively. No difference was observed between the rates of urinary shedding of patients treated with NTZ (38.9%) and patients treated with other drugs (34.5%), also no PML event was diagnosed during the follow-up. Therefore, urinary shedding might not be interfered by therapy condition. In our study, we also observed 14/27 (52%) of anti-JCV antibodies prevalence, and nearly half of them (42%) did not present any event of urinary shedding during the follow-up. J. Med. Virol. 89:528-534, 2017. © 2016 Wiley Periodicals, Inc.

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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.