Interferon-ß acts directly on T cells to prolong allograft survival by enhancing regulatory T cell induction through Foxp3 acetylation.

Type I interferons (IFNs) are pleiotropic cytokines with potent antiviral properties that also promote protective T cell and humoral immunity. Paradoxically, type I IFNs, including the widely expressed IFNß, also have immunosuppressive properties, including promoting persistent viral infections and treating T-cell-driven, remitting-relapsing multiple sclerosis. Although associative evidence suggests that IFNß mediates these immunosuppressive effects by impacting regulatory T (Treg) cells, mechanistic links remain elusive. Here, we found that IFNß enhanced graft survival in a Treg-cell-dependent murine transplant model. Genetic conditional deletion models revealed that the extended allograft survival was Treg cell-mediated and required IFNß signaling on T cells. Using an in silico computational model and analysis of human immune cells, we found that IFNß directly promoted Treg cell induction via STAT1- and P300-dependent Foxp3 acetylation. These findings identify a mechanistic connection between the immunosuppressive effects of IFNß and Treg cells, with therapeutic implications for transplantation, autoimmunity, and malignancy.

Alpha and Beta Type 1 Interferon Signaling: Passage for Diverse Biologic Outcomes.

Type I interferon (IFN-I) elicits a complex cascade of events in response to microbial infection. Here, we review recent developments illuminating the large number of IFN-I species and describing their unique biologic functions.

Differential Contributions of Interferon Classes to Host Inflammatory Responses and Restricting Virus Progeny Production.

Fundamental to mammalian intrinsic and innate immune defenses against pathogens is the production of Type I and Type II interferons, such as IFN-ß and IFN-γ, respectively. The comparative effects of IFN classes on the cellular proteome, protein interactions, and virus restriction within cell types that differentially contribute to immune defenses are needed for understanding immune signaling. Here, a multilayered proteomic analysis, paired with biochemical and molecular virology assays, allows distinguishing host responses to IFN-ß and IFN-γ and associated antiviral impacts during infection with several ubiquitous human viruses. In differentiated macrophage-like monocytic cells, we classified proteins upregulated by IFN-ß, IFN-γ, or pro-inflammatory LPS. Using parallel reaction monitoring, we developed a proteotypic peptide library for shared and unique ISG signatures of each IFN class, enabling orthogonal confirmation of protein alterations. Thermal proximity coaggregation analysis identified the assembly and maintenance of IFN-induced protein interactions. Comparative proteomics and cytokine responses in macrophage-like monocytic cells and primary keratinocytes provided contextualization of their relative capacities to restrict virus production during infection with herpes simplex virus type-1, adenovirus, and human cytomegalovirus. Our findings demonstrate how IFN classes induce distinct ISG abundance and interaction profiles that drive antiviral defenses within cell types that differentially coordinate mammalian immune responses.

Heart-specific NFAT5 knockout suppresses type I interferon signaling and aggravates coxsackievirus-induced myocarditis.

Nuclear factor of activated T cells 5 (NFAT5) is an osmosensitive transcription factor that is well-studied in renal but rarely explored in cardiac diseases. Although the association of Coxsackievirus B3 (CVB3) with viral myocarditis is well-established, the role of NFAT5 in this disease remains largely unexplored. Previous research has demonstrated that NFAT5 restricts CVB3 replication yet is susceptible to cleavage by CVB3 proteases. Using an inducible cardiac-specific Nfat5-knockout mouse model, we uncovered that NFAT5-deficiency exacerbates cardiac pathology, worsens cardiac function, elevates viral load, and reduces survival rates. RNA-seq analysis of CVB3-infected mouse hearts revealed the significant impact of NFAT5-deficiency on gene pathways associated with cytokine signaling and inflammation. Subsequent in vitro and in vivo investigation validated the disruption of the cytokine signaling pathway in response to CVB3 infection, evidenced by reduced expression of key cytokines such as interferon ß1 (IFNß1), C-X-C motif chemokine ligand 10 (CXCL10), interleukin 6 (IL6), among others. Furthermore, NFAT5-deficiency hindered the formation of stress granules, leading to a reduction of important stress granule components, including plakophilin-2, a pivotal protein within the intercalated disc, thereby impacting cardiomyocyte structure and function. These findings unveil a novel mechanism by which NFAT5 inhibits CVB3 replication and pathogenesis through the promotion of antiviral type I interferon signaling and the formation of cytoplasmic stress granules, collectively identifying NFAT5 as a new cardio protective protein.

Interferon-ß deficiency alters brain response to chronic HIV-1 envelope protein exposure in a transgenic model of NeuroHIV.

Human immunodeficiency virus-1 (HIV-1) infects the central nervous system (CNS) and causes HIV-associated neurocognitive disorders (HAND) in about half of the population living with the virus despite combination anti-retroviral therapy (cART). HIV-1 activates the innate immune system, including the production of type 1 interferons (IFNs) α and ß. Transgenic mice expressing HIV-1 envelope glycoprotein gp120 (HIVgp120tg) in the CNS develop memory impairment and share key neuropathological features and differential CNS gene expression with HIV patients, including the induction of IFN-stimulated genes (ISG). Here we show that knocking out IFNß (IFNßKO) in HIVgp120tg and non-tg control mice impairs recognition and spatial memory, but does not affect anxiety-like behavior, locomotion, or vision. The neuropathology of HIVgp120tg mice is only moderately affected by the KO of IFNß but in a sex-dependent fashion. Notably, in cerebral cortex of IFNßKO animals presynaptic terminals are reduced in males while neuronal dendrites are reduced in females. The IFNßKO results in the hippocampal CA1 region of both male and female HIVgp120tg mice in an ameliorated loss of neuronal presynaptic terminals but no protection of neuronal dendrites. Only female IFNß-deficient HIVgp120tg mice display diminished microglial activation in cortex and hippocampus and increased astrocytosis in hippocampus compared to their IFNß-expressing counterparts. RNA expression for some immune genes and ISGs is also affected in a sex-dependent way. The IFNßKO abrogates or diminishes the induction of MX1, DDX58, IRF7 and IRF9 in HIVgp120tg brains of both sexes. Expression analysis of neurotransmission related genes reveals an influence of IFNß on multiple components with more pronounced changes in IFNßKO females. In contrast, the effects of IFNßKO on MAPK activities are independent of sex with pronounced reduction of active ERK1/2 but also of active p38 in the HIVgp120tg brain. In summary, our findings show that the absence of IFNß impairs memory dependent behavior and modulates neuropathology in HIVgp120tg brains, indicating that its absence may facilitate development of HAND. Moreover, our data suggests that endogenous IFNß plays a vital role in maintaining neuronal homeostasis and memory function.

Preventing occludin tight-junction disruption via inhibition of microRNA-193b-5p attenuates viral load and influenza-induced lung injury.

Virus-induced lung injury is associated with loss of pulmonary epithelial-endothelial tight junction integrity. While the alveolar-capillary membrane may be an indirect target of injury, viruses may interact directly and/or indirectly with miRs to augment their replication potential and evade the host antiviral defense system. Here, we expose how the influenza virus (H1N1) capitalizes on host-derived interferon-induced, microRNA (miR)-193b-5p to target occludin and compromise antiviral defenses. Lung biopsies from patients infected with H1N1 revealed increased miR-193b-5p levels, marked reduction in occludin protein, and disruption of the alveolar-capillary barrier. In C57BL/6 mice, the expression of miR-193b-5p increased, and occludin decreased, 5-6 days post-infection with influenza (PR8). Inhibition of miR-193b-5p in primary human bronchial, pulmonary microvascular, and nasal epithelial cells enhanced antiviral responses. miR-193b-deficient mice were resistant to PR8. Knockdown of occludin, both in vitro and in vivo, and overexpression of miR-193b-5p reconstituted susceptibility to viral infection. miR-193b-5p inhibitor mitigated loss of occludin, improved viral clearance, reduced lung edema, and augmented survival in infected mice. Our results elucidate how the innate immune system may be exploited by the influenza virus and how strategies that prevent loss of occludin and preserve tight junction function may limit susceptibility to virus-induced lung injury.

Early Treatment of High-Risk Hospitalized Coronavirus Disease 2019 (COVID-19) Patients With a Combination of Interferon Beta-1b and Remdesivir: A Phase 2 Open-label Randomized Controlled Trial.

BACKGROUND: Early antiviral therapy was effective in the treatment of coronavirus disease 2019 (COVID-19). We assessed the efficacy and safety of combined interferon beta-1b and remdesivir treatment in hospitalized COVID-19 patients. METHODS: We conducted a multicentre, prospective open-label, randomized-controlled trial involving high-risk adults hospitalized for COVID-19. Patients were randomly assigned to a 5-day interferon beta-1b 16 million units daily and remdesivir 200 mg loading on day 1 followed by 100 mg daily on day 2 to 5 (combination group), or to remdesivir only of similar regimen (control group) (1:1). The primary endpoint was the time to complete alleviation of symptoms (NEWS2 = 0). RESULTS: Two-hundred and twelve patients were enrolled. The median days of starting treatment from symptom onset was 3 days. The median age was 65 years, and 159 patients (75%) had chronic disease. The baseline demographics were similar. There was no mortality. For the primary endpoint, the combination group was significantly quicker to NEWS2 = 0 (4 vs 6.5 days; hazard ratio [HR], 6.59; 95% confidence interval [CI], 6.1-7.09; P < .0001) when compared to the control group. For the secondary endpoints, the combination group was quicker to negative nasopharyngeal swab (NPS) viral load (VL) (6 vs 8 days; HR, 8.16; 95% CI, 7.79-8.52; P < .0001) and to develop seropositive immunoglobulin G (IgG) (8 vs 10 days; HR, 10.78; 95% CI, 9.98-11.58; P < .0001). All adverse events resolved upon follow-up. Combination group (HR, 4.1 95% CI, 1.9-8.6, P < .0001) was the most significant independent factor associated with NEWS2 = 0 on day 4. CONCLUSIONS: Early treatment with interferon beta-1b and remdesivir was safe and better than remdesivir only in alleviating symptoms, and in shortening viral shedding and hospitalization with earlier seropositivity in high-risk COVID-19 patients. CLINICAL TRIALS REGISTRATION: NCT04647695.

Pellino3 ligase negatively regulates influenza B dependent RIG-I signalling through downregulation of TRAF3-mediated induction of the transcription factor IRF3 and IFNß production.

Viral infection activates the innate immune system, which recognizes viral components by a variety of pattern recognition receptors and initiates signalling cascades leading to the production of pro-inflammatory cytokines. To date, signalling cascades triggered after virus recognition are not fully characterized and are investigated by many research groups. The critical role of the E3 ubiquitin ligase Pellino3 in antibacterial and antiviral response is now widely accepted, but the precise mechanism remains elusive. In this study, we sought to explore Pellino3 role in the retinoic acid-inducible gene I (RIG-I)-dependent signalling pathway. In this work, the molecular mechanisms of the innate immune response, regulated by Pellino3, were investigated in lung epithelial cells during influenza B virus infection. We used wild-type and Pellino3-deficient A549 cells as model cell lines to examine the role of Pellino3 ligase in the type I interferon (IFN) signalling pathway. Our results indicate that Pellino3 is involved in direct ubiquitination and degradation of the TRAF3, suppressing interferon regulatory factor 3 (IRF3) activation and interferon beta (IFNß) production.

The parapoxvirus Orf virus inhibits dsDNA-mediated type I IFN expression via STING-dependent and STING-independent signalling pathways.

Type I interferons (IFNs) are critical in the host defence against viruses. They induce hundreds of interferon-stimulated genes (ISGs) many of which have an antiviral role. Poxviruses induce IFNs via their pathogen-associated molecular patterns, in particular, their genomic DNA. In a majority of cell types, dsDNA is detected by a range of cytoplasmic DNA sensors that mediate type I IFN expression via stimulator of interferon genes (STING). Orf virus (ORFV) induces cutaneous pustular skin lesions and is the type species of the Parapoxvirus genus within the Poxviridae family. The aim of this study was to investigate whether ORFV modulates dsDNA-induced type I IFN expression via STING-dependent signalling pathways in human dermal fibroblasts (hNDF) and THP-1 cells. We showed that ORFV infection of these cell types treated with poly(dA:dT) resulted in strong inhibition of expression of IFN-ß. In hNDFs, we showed using siRNA knock-down that STING was essential for type I IFN induction. IFN-ß expression was further reduced when both STING and RIG-I were knocked down. In addition, HEK293 cells that do not express STING or Toll-like receptors also produce IFN-ß following stimulation with poly(dA:dT). The 5' triphosphate dsRNA produced by RNA polymerase III specifically results in the induction of type I IFNs through the RIG-I receptor. We showed that ORFV infection resulted in strong inhibition of IFN-ß expression in HEK293 cells stimulated with poly(dA:dT). Overall, this study shows that ORFV potently counteracts the STING-dependent and STING-independent IFN response by antagonizing dsDNA-activated IFN signalling pathways.

Respiratory Syncytial Virus Protects Bystander Cells against Influenza A Virus Infection by Triggering Secretion of Type I and Type III Interferons.

We observed the interference between two prevalent respiratory viruses, respiratory syncytial virus (RSV) and influenza A virus (IAV) (H1N1), and characterized its molecular underpinnings in alveolar epithelial cells (A549). We found that RSV induces higher levels of interferon beta (IFN-ß) production than IAV and that IFN-ß priming confers higher-level protection against infection with IAV than with RSV. Consequently, we focused on the sequential infection scheme of RSV and then IAV. Using A549 wild-type (WT), IFNAR1 knockout (KO), IFNLR1 KO, and IFNAR1-IFNLR1 double-KO cell lines, we found that both IFN-ß and IFN-λ are necessary for maximum protection against subsequent infection. Immunostaining revealed that preinfection with RSV partitions the cell population into a subpopulation susceptible to subsequent infection with IAV and an IAV-proof subpopulation. Strikingly, the susceptible cells turned out to be those already compromised and efficiently expressing RSV, whereas the bystander, interferon-primed cells are resistant to IAV infection. Thus, virus-virus exclusion at the cell population level is not realized through direct competition for a shared ecological niche (single cell) but rather is achieved with the involvement of specific cytokines induced by the host's innate immune response. IMPORTANCE Influenza A virus (IAV) and respiratory syncytial virus (RSV) are common recurrent respiratory infectants that show a relatively high coincidence. We demonstrated that preinfection with RSV partitions the cell population into a subpopulation susceptible to subsequent infection with IAV and an IAV-proof subpopulation. The susceptible cells are those already compromised and efficiently expressing RSV, whereas the bystander cells are resistant to IAV infection. The cross-protective effect critically depends on IFN-ß and IFN-λ signaling and thus ensues when the proportion of cells preinfected with RSV is relatively low yet sufficient to trigger a pervasive antiviral state in bystander cells. Our study suggests that mild, but not severe, respiratory infections may have a short-lasting protective role against more dangerous respiratory viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Sex-dependent expression levels of VAV1 and P2X7 in PBMC of multiple sclerosis patients.

Multiple sclerosis (MS) is an inflammatory autoimmune disorder of the central nervous system and the leading cause of progressive neurological disability in young adults. It decreases the patient's lifespan by about 10 years and affects women more than men. No medication entirely restricts or reverses neurological degradation. However, early diagnosis and treatment increase the possibility of a better outcome. To identify new MS biomarkers, we tested the expression of six potential markers (P2X4, P2X7, CXCR4, RGS1, RGS16 and VAV1) using qPCR in peripheral blood mononuclear cells (PBMC) of MS patients treated with interferon ß (IFNß), with glatiramer acetate (GA) or untreated. We showed that P2X7 and VAV1 are significantly induced in MS patients. In contrast, the expression of P2X4, CXCR4, RGS1 and RGS16 was not significantly modified by MS in PBMC. P2X7 and VAV1 are essentially induced in female patients, suggesting these markers are connected to sex-specific mechanisms. Strikingly, VAV1 expression is higher in healthy women than healthy men and IFNß treatment of MS reduced VAV1 expression in female MS patients while it up-regulated VAV1 in male MS patients. Our data point to the differential, sex-dependent value of MS markers and treatment effects. Although rgs16 expression in PBMC was not a valid MS marker in patients, the strong upregulation of P2X4 and P2X7 induced in the spinal cord of WT mice by EAE was abrogated in rgs16KO mice suggesting that rgs16 is required for P2X4 and P2X7 induction by neurological diseases.

Placenta-derived interferon-stimulated gene 20 controls ZIKA virus infection.

Zika virus is a positive-sense single-stranded RNA virus, which can be transmitted across the placenta and has adverse effects on fetal development during pregnancy. The severity of these complications highlights the importance of prevention and treatment. However, no vaccines or drugs are currently available. In this study, we characterize the IFNß-mediated anti-viral response in trophoblast cells in order to identify critical components that are necessary for the successful control of viral replication and determine whether components of the IFN-induced response can be used as a replacement therapy for ZIKA virus infection during pregnancy. We identify and characterize interferon-stimulated gene 20 (ISG20) as playing a central role in controlling Zika virus infection in trophoblast cells and successfully establish a recombinant ISG20-Fc protein that effectively decreases viral titers in vitro and in vivo by maintaining its exonuclease activity and displaying potential immune modulatory functions. Recombinant ISG20-Fc has thus the potential to be further developed as an anti-viral treatment against ZIKA viral infection in high-risk populations, particularly in pregnant women.

Thrombotic microangiopathy due to acquired complement factor I deficiency in a male receiving interferon-beta treatment for multiple sclerosis.

AIMS: Interferon-beta (IFNß), the most widely prescribed medication for multiple sclerosis, is generally considered safe. Nevertheless, rare serious and/or life-threatening side effects have been reported such as thrombotic microangiopathy. A few mechanisms have been proposed to explain how interferon causes thrombotic microangiopathy, but immunological studies have been unable to pin this phenomenon down to a single pathophysiologic pathway. The aim of this article was to report a new mechanism explaining Interferon beta related thrombotic microangiopathy. METHODS: We report thrombotic microangiopathy in a 28-year-old male receiving interferon-beta treatment for multiple sclerosis. RESULTS: After three years of starting interferon beta therapy, the patient presented with malignant hypertension causing seizures, rapidly progressive renal failure requiring haemodialysis and haemolytic anaemia. Corticosteroid and plasma exchange sessions permitted haemolysis control. Nonetheless, the patient remained hemodialysis-dependent. Exploration of the complement system found a complement factor I deficiency whose activity normalized at the control carried out after 2 years. CONCLUSION: IFNß treatment may cause complement factor I deficit, which can lead to thrombotic microangiopathy and severe renal failure.

The MC160 protein of the molluscum contagiosum virus dampens cGAS/STING-induced interferon-ß activation.

Molluscum contagiosum virus (MCV) is a poxvirus that causes benign, persistent skin lesions. MCV encodes a variety of immune evasion molecules to dampen host immune responses. Two of these proteins are the MC159 and MC160 proteins. Both MC159 and MC160 contain two tandem death effector domains and share homology to the cellular FLIPs, FADD, and procaspase-8. MC159 and MC160 dampen several innate immune responses such as NF-κB activation and mitochondrial antiviral signaling (MAVS)-mediated induction of type 1 interferon (IFN). The type 1 IFN response is also activated by the cytosolic DNA sensors cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING). Both cGAS and STING play a vital role in sensing a poxvirus infection. In this study, we demonstrate that there are nuanced differences between both MC160 and MC159 in terms of how the viral proteins modulate the cGAS/STING and MAVS pathways. Specifically, MC160 expression, but not MC159 expression, dampens cGAS/STING-mediated induction of IFN in HEK 293 T cells. Further, MC160 expression prevented the K63-ubiquitination of both STING and TBK1, a kinase downstream of cGAS/STING. Ectopic expression of the MC160 protein, but not the MC159 protein, resulted in a measurable decrease in the TBK1 protein levels as detected via immunoblotting. Finally, using a panel of MC160 truncation mutants, we report that the MC160 protein requires both DEDs to inhibit cGAS/STING-induced activation of IFN-ß. Our model indicates MC160 likely alters the TBK1 signaling complex to decrease IFN-ß activation at the molecular intersection of the cGAS/STING and MAVS signaling pathways.

Interferon Beta-1a versus Glatiramer Acetate: Changes of Innate Immunity in a Group of Women with Multiple Sclerosis.

INTRODUCTION: Multiple sclerosis (MS) is a chronic inflammatory autoimmune demyelinating disease that secondarily leads to axonal loss and associated brain atrophy. Disease-modifying drugs (DMDs) have previously been studied for their ability to affect specific immunity. This study investigates the effect of interferon beta-1a (INF) and glatiramer acetate (GA) administration on changes in innate immunity cell populations. METHODS: Sixty Caucasian female patients with relapsing-remitting MS undergo blood sample testing for 15 blood parameters at baseline, 1 month, 3 months, and 6 months after treatment by GA or IFN (started as their first-line DMD). RESULTS: A statistically significant difference in the change after 6 months was found in the parameter monocytes (relative count) in the group of patients treated with IFN. The median increase was 27.8%. Changes in many of the other 15 parameters studied were 10-20%. CONCLUSION: Innate immunity has long been neglected in MS immunopathology. The findings suggest that IFN treatment may modulate the immune response in MS by affecting monocyte function and may provide insight into the mechanisms of action of IFN in MS.

Global DNA Methylation and Hydroxymethylation Levels in PBMCs Are Altered in RRMS Patients Treated with IFN-ß and GA-A Preliminary Study.

Multiple sclerosis (MS) is a chronic disease affecting the central nervous system (CNS) due to an autoimmune attack on axonal myelin sheaths. Epigenetics is an open research topic on MS, which has been investigated in search of biomarkers and treatment targets for this heterogeneous disease. In this study, we quantified global levels of epigenetic marks using an ELISA-like approach in Peripheral Blood Mononuclear Cells (PBMCs) from 52 patients with MS, treated with Interferon beta (IFN-ß) and Glatiramer Acetate (GA) or untreated, and 30 healthy controls. We performed media comparisons and correlation analyses of these epigenetic markers with clinical variables in subgroups of patients and controls. We observed that DNA methylation (5-mC) decreased in treated patients compared with untreated and healthy controls. Moreover, 5-mC and hydroxymethylation (5-hmC) correlated with clinical variables. In contrast, histone H3 and H4 acetylation did not correlate with the disease variables considered. Globally quantified epigenetic DNA marks 5-mC and 5-hmC correlate with disease and were altered with treatment. However, to date, no biomarker has been identified that can predict the potential response to therapy before treatment initiation.

Roles of the ubiquitin ligase CUL4B and ADP-ribosyltransferase TiPARP in TCDD-induced nuclear export and proteasomal degradation of the transcription factor AHR.

The aryl hydrocarbon receptor (AHR) is a transcription factor activated by exogenous halogenated polycyclic aromatic hydrocarbon compounds, including the environmental toxin TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and naturally occurring dietary and endogenous compounds. The activated AHR enhances transcription of specific genes including phase I and phase II metabolism enzymes and other targets genes such as the TCDD-inducible poly(ADP-ribose) polymerase (TiPARP). The regulation of AHR activation is a dynamic process: immediately after transcriptional activation of the AHR by TCDD, the AHR is exported from the nucleus to the cytoplasm where it is subjected to proteasomal degradation. However, the mechanisms regulating AHR degradation are not well understood. Here, we studied the role of two enzymes reported to enhance AHR breakdown: the cullin 4B (CUL4B)AHR complex, an E3 ubiquitin ligase that targets the AHR and other proteins for ubiquitination, and TiPARP, which targets proteins for ADP-ribosylation, a posttranslational modification that can increase susceptibility to degradation. Using a WT mouse embryonic fibroblast (MEF) cell line and an MEF cell line in which CUL4B has been deleted (MEFCul4b-null), we discovered that loss of CUL4B partially prevented AHR degradation after TCDD exposure, while knocking down TiPARP in MEFCul4b-null cells completely abolished AHR degradation upon TCDD treatment. Increased TCDD-activated AHR protein levels in MEFCul4b-null and MEFCul4b-null cells in which TiPARP was knocked down led to enhanced AHR transcriptional activity, indicating that CUL4B and TiPARP restrain AHR action. This study reveals a novel function of TiPARP in controlling TCDD-activated AHR nuclear export and subsequent proteasomal degradation.

Zika virus infection of mature neurons from immunocompetent mice generates a disease-associated microglia and a tauopathy-like phenotype in link with a delayed interferon beta response.

BACKGROUND: Zika virus (ZIKV) infection at postnatal or adult age can lead to neurological disorders associated with cognitive defects. Yet, how mature neurons respond to ZIKV remains substantially unexplored. METHODS: The impact of ZIKV infection on mature neurons and microglia was analyzed at the molecular and cellular levels, in vitro using immunocompetent primary cultured neurons and microglia, and in vivo in the brain of adult immunocompetent mice following intracranial ZIKV inoculation. We have used C57BL/6 and the genetically diverse Collaborative Cross mouse strains, displaying a broad range of susceptibility to ZIKV infection, to question the correlation between the effects induced by ZIKV infection on neurons and microglia and the in vivo susceptibility to ZIKV. RESULTS: As a result of a delayed induction of interferon beta (IFNB) expression and response, infected neurons displayed an inability to stop ZIKV replication, a trait that was further increased in neurons from susceptible mice. Alongside with an enhanced expression of ZIKV RNA, we observed in vivo, in the brain of susceptible mice, an increased level of active Iba1-expressing microglial cells occasionally engulfing neurons and displaying a gene expression profile close to the molecular signature of disease-associated microglia (DAM). In vivo as well as in vitro, only neurons and not microglial cells were identified as infected, raising the question of the mechanisms underlying microglia activation following brain ZIKV infection. Treatment of primary cultured microglia with conditioned media from ZIKV-infected neurons demonstrated that type-I interferons (IFNs-I) secreted by neurons late after infection activate non-infected microglial cells. In addition, ZIKV infection induced pathological phosphorylation of Tau (pTau) protein, a hallmark of neurodegenerative tauopathies, in vitro and in vivo with clusters of neurons displaying pTau surrounded by active microglial cells. CONCLUSIONS: We show that ZIKV-infected mature neurons display an inability to stop viral replication in link with a delayed IFNB expression and response, while signaling microglia for activation through IFNs-I secreted at late times post-infection. In the brain of ZIKV-infected susceptible mice, uninfected microglial cells adopt an active morphology and a DAM expression profile, surrounding and sometimes engulfing neurons while ZIKV-infected neurons accumulate pTau, overall reflecting a tauopathy-like phenotype.

Encephalomyocarditis Virus Abrogates the Interferon Beta Signaling Pathway via Its Structural Protein VP2.

Type I interferon (IFN)-mediated antiviral responses are critical for modulating host-virus responses, and indeed, viruses have evolved strategies to antagonize this pathway. Encephalomyocarditis virus (EMCV) is an important zoonotic pathogen, which causes myocarditis, encephalitis, neurological disease, reproductive disorders, and diabetes in pigs. This study aims to understand how EMCV interacts with the IFN pathway. EMCV circumvents the type I IFN response by expressing proteins that antagonize cellular innate immunity. Here, we show that EMCV VP2 is a negative regulator of the IFN-ß pathway. This occurs via the degradation of the MDA5-mediated cytoplasmic double-stranded RNA (dsRNA) antiviral sensing RIG-I-like receptor (RLR) pathway. We show that structural protein VP2 of EMCV interacts with MDA5, MAVS, and TBK1 through its C terminus. In addition, we found that EMCV VP2 could significantly degrade RLRs by the proteasomal and lysosomal pathways. For the first time, EMCV VP2 was shown to play an important role in EMCV evasion of the type I IFN signaling pathway. This study expands our understanding that EMCV utilizes its capsid protein VP2 to evade the host antiviral response.IMPORTANCE Encephalomyocarditis virus is an important pathogen that can cause encephalitis, myocarditis, neurological diseases, and reproductive disorders. It also causes huge economic losses for the swine industry worldwide. Innate immunity plays an important role in defending the host from pathogen infection. Understanding pathogen microorganisms evading the host immune system is of great importance. Currently, whether EMCV evades cytosolic RNA sensing and signaling is still poorly understood. In the present study, we found that viral protein VP2 antagonized the RLR signaling pathway by degrading MDA5, MAVS, and TBK1 protein expression to facilitate viral replication in HEK293 cells. The findings in this study identify a new mechanism for EMCV evading the host's innate immune response, which provide new insights into the virus-host interaction and help develop new antiviral approaches against EMCV.

Risk of requiring a walking aid after 6.5 years of ocrelizumab treatment in patients with relapsing multiple sclerosis: Data from the OPERA I and OPERA II trials.

BACKGROUND AND PURPOSE: Requiring a walking aid is a fundamental milestone in multiple sclerosis (MS), represented by an Expanded Disability Status Scale (EDSS) score ≥6.0. In the present study, we assess the effect of ocrelizumab (OCR) on time to EDSS score ≥6.0 in relapsing MS. METHODS: Time to EDSS score ≥6.0 confirmed for ≥24 and ≥48 weeks was assessed over the course of 6.5 years (336 weeks) in the double-blind period (DBP) and open-label extension (OLE) period of the OPERA I (NCT01247324) and OPERA II (NCT01412333) studies. RESULTS: Time to reach EDSS score ≥6.0 was significantly delayed in those initially randomized to OCR versus interferon. Over 6.5 years, the risk of requiring a walking aid confirmed for ≥24 weeks was 34% lower among those who initiated OCR earlier versus delayed treatment (average hazard ratio [HR] DBP + OLE 0.66, 95% confidence interval [CI] 0.45-0.95; p = 0.024); the risk of requiring a walking aid confirmed for ≥48 weeks was 46% lower (average HR DBP+OLE 0.54, 95% CI 0.35-0.83; p = 0.004). CONCLUSION: The reduced risk of requiring a walking aid in earlier initiators of OCR demonstrates the long-term implications of earlier highly effective treatment.