ABSTRACT
Severe fever with thrombocytopenia syndrome (SFTS) has a high mortality rate compared to other infectious diseases. SFTS is particularly associated with a high risk of mortality in immunocompromised individuals, while most patients who die of SFTS exhibit symptoms of severe encephalitis before death. However, the region of brain damage and mechanisms by which the SFTS virus (SFTSV) causes encephalitis remains unknown. Here, we revealed that SFTSV infects the brainstem and spinal cord, which are regions of the brain associated with respiratory function, and motor nerves in IFNAR1-/- mice. Further, we show that A1-reactive astrocytes are activated, causing nerve cell death, in infected mice. Primary astrocytes of SFTSV-infected IFNAR1-/- mice also induced neuronal cell death through the activation of A1-reactive astrocytes. Herein, we showed that SFTSV induces fatal neuroinflammation in the brain regions important for respiratory function and motor nerve, which may underlie mortality in SFTS patients. This study provides new insights for the treatment of SFTS, for which there is currently no therapeutic approach.
Subject(s)
Astrocytes , Bunyaviridae Infections , Mice, Knockout , Phlebovirus , Receptor, Interferon alpha-beta , Animals , Astrocytes/virology , Astrocytes/pathology , Mice , Receptor, Interferon alpha-beta/genetics , Receptor, Interferon alpha-beta/deficiency , Phlebovirus/genetics , Phlebovirus/physiology , Phlebovirus/pathogenicity , Bunyaviridae Infections/virology , Bunyaviridae Infections/pathology , Bunyaviridae Infections/immunology , Brain/virology , Brain/pathology , Brain/immunology , Spinal Cord/virology , Spinal Cord/pathology , Disease Models, Animal , Neurons/virology , Neurons/pathology , Mice, Inbred C57BL , Brain Stem/virology , Brain Stem/pathology , Cell DeathABSTRACT
Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease affecting the central nervous system (CNS) in animals that parallels several clinical and molecular traits of multiple sclerosis in humans. Herpes simplex virus type 1 (HSV-1) infection mainly causes cold sores and eye diseases, yet eventually, it can also reach the CNS, leading to acute encephalitis. Notably, a significant proportion of healthy individuals are likely to have asymptomatic HSV-1 brain infection with chronic brain inflammation due to persistent latent infection in neurons. Because cellular senescence is suggested as a potential factor contributing to the development of various neurodegenerative disorders, including multiple sclerosis, and viral infections may induce a premature senescence state in the CNS, potentially increasing susceptibility to such disorders, here we examine the presence of senescence-related markers in the brains and spinal cords of mice with asymptomatic HSV-1 brain infection, EAE, and both conditions. Across all scenarios, we find a significant increases of senescence biomarkers in the CNS with some differences depending on the analyzed group. Notably, some senescence biomarkers are exclusively observed in mice with the combined conditions. These results indicate that asymptomatic HSV-1 brain infection and EAE associate with a significant expression of senescence biomarkers in the CNS.
Subject(s)
Brain , Cellular Senescence , Herpes Simplex , Herpesvirus 1, Human , Multiple Sclerosis , Animals , Mice , Brain/virology , Brain/pathology , Brain/metabolism , Multiple Sclerosis/virology , Multiple Sclerosis/pathology , Multiple Sclerosis/metabolism , Herpesvirus 1, Human/physiology , Herpesvirus 1, Human/pathogenicity , Herpes Simplex/virology , Herpes Simplex/pathology , Female , Mice, Inbred C57BL , Encephalomyelitis, Autoimmune, Experimental/virology , Encephalomyelitis, Autoimmune, Experimental/pathology , Encephalomyelitis, Autoimmune, Experimental/metabolism , Phenotype , Central Nervous System/virology , Central Nervous System/metabolism , Central Nervous System/pathology , Spinal Cord/virology , Spinal Cord/metabolism , Spinal Cord/pathology , Biomarkers/metabolism , Encephalitis, Herpes Simplex/virology , Encephalitis, Herpes Simplex/pathology , Encephalitis, Herpes Simplex/metabolismABSTRACT
Enterovirus D68 (EV-D68) is an emerging pathogen that can cause severe respiratory and neurologic disease [acute flaccid myelitis (AFM)]. Intramuscular (IM) injection of neonatal Swiss Webster (SW) mice with US/IL/14-18952 (IL52), a clinical isolate from the 2014 EV-D68 epidemic, results in many of the pathogenic features of human AFM, including viral infection of the spinal cord, death of motor neurons, and resultant progressive paralysis. In distinction, CA/14-4231 (CA4231), another clinical isolate from the 2014 EV-D68 outbreak, does not cause paralysis in mice, does not grow in the spinal cord, and does not cause motor neuron loss following IM injection. A panel of chimeric viruses containing sequences from IL52 and CA4231 was used to demonstrate that VP1 is the main determinant of EV-D68 neurovirulence following IM injection of neonatal SW mice. VP1 contains four amino acid differences between IL52 and CA4231. Mutations resulting in substituting these four amino acids (CA4231 residues into the IL52 polyprotein) completely abolished neurovirulence. Conversely, mutations resulting in substituting VP1 IL52 amino acid residues into the CA4231 polyprotein created a virus that induced paralysis to the same degree as IL52. Neurovirulence following infection of neonatal SW mice with parental and chimeric viruses was associated with viral growth in the spinal cord. IMPORTANCE: Emerging viruses allow us to investigate mutations leading to increased disease severity. Enterovirus D68 (EV-D68), once the cause of rare cases of respiratory illness, recently acquired the ability to cause severe respiratory and neurologic disease. Chimeric viruses were used to demonstrate that viral structural protein VP1 determines growth in the spinal cord, motor neuron loss, and paralysis following intramuscular (IM) injection of neonatal Swiss Webster (SW) mice with EV-D68. These results have relevance for predicting the clinical outcome of future EV-D68 epidemics as well as targeting retrograde transport as a potential strategy for treating virus-induced neurologic disease.
Subject(s)
Capsid Proteins , Central Nervous System Viral Diseases , Disease Models, Animal , Enterovirus D, Human , Enterovirus Infections , Myelitis , Neuromuscular Diseases , Animals , Enterovirus D, Human/pathogenicity , Enterovirus D, Human/genetics , Enterovirus D, Human/physiology , Myelitis/virology , Mice , Enterovirus Infections/virology , Enterovirus Infections/pathology , Neuromuscular Diseases/virology , Neuromuscular Diseases/pathology , Capsid Proteins/genetics , Capsid Proteins/metabolism , Central Nervous System Viral Diseases/virology , Central Nervous System Viral Diseases/pathology , Humans , Spinal Cord/virology , Spinal Cord/pathology , Motor Neurons/virology , Motor Neurons/pathology , Animals, Newborn , Virulence , Paralysis/virologyABSTRACT
Despite antiretroviral therapy (ART), HIV-associated peripheral neuropathy remains one of the most prevalent neurologic manifestations of HIV infection. The spinal cord is an essential component of sensory pathways, but spinal cord sampling and evaluation in people with HIV has been very limited, especially in those on ART. The SIV/macaque model allows for assessment of the spinal cord at key time points throughout infection with and without ART. In this study, RNA was isolated from the spinal cord of uninfected, SIV+, and SIV + ART animals to track alterations in gene expression using global RNA-seq. Next, the SeqSeek platform was used to map changes in gene expression to specific cell types. Pathway analysis of differentially expressed genes demonstrated that highly upregulated genes in SIV-infected spinal cord aligned with interferon and viral response pathways. Additionally, this upregulated gene set significantly overlapped with those expressed in myeloid-derived cells including microglia. Downregulated genes were involved in cholesterol and collagen biosynthesis, and TGF-b regulation of extracellular matrix. In contrast, enriched pathways identified in SIV + ART animals included neurotransmitter receptors and post synaptic signaling regulators, and transmission across chemical synapses. SeqSeek analysis showed that upregulated genes were primarily expressed by neurons rather than glia. These findings indicate that pathways activated in the spinal cord of SIV + ART macaques are predominantly involved in neuronal signaling rather than proinflammatory pathways. This study provides the basis for further evaluation of mechanisms of SIV infection + ART within the spinal cord with a focus on therapeutic interventions to maintain synaptodendritic homeostasis.
Subject(s)
Neuroglia , Neurons , Simian Acquired Immunodeficiency Syndrome , Spinal Cord , Animals , Simian Acquired Immunodeficiency Syndrome/metabolism , Simian Acquired Immunodeficiency Syndrome/genetics , Simian Acquired Immunodeficiency Syndrome/drug therapy , Spinal Cord/metabolism , Spinal Cord/drug effects , Spinal Cord/virology , Neuroglia/metabolism , Neuroglia/drug effects , Neuroglia/virology , Neurons/metabolism , Neurons/drug effects , Neurons/virology , Anti-Retroviral Agents/therapeutic use , Anti-Retroviral Agents/pharmacology , Simian Immunodeficiency Virus/drug effects , Macaca mulatta , Gene Expression/drug effects , Male , Gene Expression Regulation/drug effectsABSTRACT
IMPORTANCE: Viral encephalomyelitis outcome is dependent on host responses to neuronal infection. Interferon (IFN) is an important component of the innate response, and IFN regulatory factor (IRF) 7 is an inducible transcription factor for the synthesis of IFN-α. IRF7-deficient mice develop fatal paralysis after CNS infection with Sindbis virus, while wild-type mice recover. Irf7 -/- mice produce low levels of IFN-α but high levels of IFN-ß with induction of IFN-stimulated genes, so the reason for this difference is not understood. The current study shows that Irf7 -/- mice developed inflammation earlier but failed to clear virus from motor neuron-rich regions of the brainstem and spinal cord. Levels of IFN-γ and virus-specific antibody were comparable, indicating that IRF7 deficiency does not impair expression of these known viral clearance factors. Therefore, IRF7 is either necessary for the neuronal response to currently identified mediators of clearance or enables the production of additional antiviral factor(s) needed for clearance.
Subject(s)
Alphavirus Infections , Encephalomyelitis , Interferon Regulatory Factor-7 , Sindbis Virus , Animals , Mice , Alphavirus Infections/immunology , Alphavirus Infections/virology , Brain Stem/virology , Encephalomyelitis/immunology , Encephalomyelitis/virology , Inflammation/virology , Interferon Regulatory Factor-7/deficiency , Interferon Regulatory Factor-7/genetics , Interferon Regulatory Factor-7/metabolism , Interferon-beta/immunology , Interferon-beta/metabolism , Motor Neurons/virology , Sindbis Virus/immunology , Spinal Cord/virologyABSTRACT
The complexity of the central nervous system (CNS) is not recapitulated in cell culture models. Thin slicing and subsequent culture of CNS tissue has become a valued means to study neuronal and glial biology within the context of the physiologically relevant tissue milieu. Modern membrane-interface slice culturing methodology allows for straightforward access to both CNS tissue and feeding medium, enabling experimental manipulations and analyses that would otherwise be impossible in vivo. CNS slices can be successfully maintained in culture for up to several weeks for investigation of evolving pathology and long-term intervention in models of chronic neurologic disease.Herein, membrane-interface slice culture models for studying viral encephalitis and myelitis are detailed, with emphasis on the use of these models for investigation of pathogenesis and evaluation of novel treatment strategies. We describe techniques to (1) generate brain and spinal cord slices from rodent donors, (2) virally infect slices, (3) monitor viral replication, (4) assess virally induced injury/apoptosis, (5) characterize "CNS-specific" cytokine production, and, (6) treat slices with cytokines/pharmaceuticals. Although our focus is on CNS viral infection, we anticipate that the described methods can be adapted to address a wide range of investigations within the fields of neuropathology, neuroimmunology, and neuropharmacology.
Subject(s)
Brain/virology , Encephalitis, Viral/virology , Myelitis/virology , Spinal Cord/virology , Animals , Animals, Newborn , Antiviral Agents/pharmacology , Apoptosis , Brain/drug effects , Brain/metabolism , Brain/pathology , Cytokines/metabolism , Encephalitis, Viral/drug therapy , Encephalitis, Viral/metabolism , Encephalitis, Viral/pathology , Host-Pathogen Interactions , Inflammation Mediators/metabolism , Mice , Myelitis/drug therapy , Myelitis/metabolism , Myelitis/pathology , Spinal Cord/drug effects , Spinal Cord/metabolism , Spinal Cord/pathology , Tissue Culture Techniques , Virus ReplicationABSTRACT
Se desarrollan los principales elementos históricos en el estudio y la lucha contra la poliomielitis, su aislamiento por Karl Landsteiner en 1909, la primera vacuna con virus muerto (Jonas Salk, 1955), la segunda vacuna con virus vivo atenuado (Albert Sabin, 1961) y la reducción paulatina de la polio en todo el mundo, hasta llegar a menos de 200 casos al año (virus salvaje)(AU)
The main historical events in the study and fight against polio are shown, its isolation by Karl Landsteiner in 1909, the development of the first vaccine with dead virus (Jonas Salk, 1955), the second vaccine with live attenuated virus (Albert Sabin, 1961) and the gradual reduction of polio worldwide, reaching less than 200 cases a year (wild virus)(AU)
Subject(s)
Poliomyelitis/mortality , Poliomyelitis/virology , Central Nervous System Viral Diseases , Poliovirus , Spinal Cord/virology , Poliovirus Vaccine, Inactivated , Poliovirus Vaccine, OralABSTRACT
BACKGROUND: Genetics have provided hints on potential molecular pathways involved in neurodegenerative diseases (NDD). However, the number of cases caused exclusively by genetic alterations is low, suggesting an important contribution of environmental factors to NDDs. Among these factors, viruses like herpes simplex viruses (HSV-2), capable of establishing lifelong infections within the nervous system (NS), are being proposed to have a role in NDDs. Despite promising data, there is a significant lack of knowledge on this and an urgent need for more research. METHODS: We have set up a mouse model to study HSV latency and its associated neuroinflammation in the spinal cord. The goal of this model was to observe neuroinflammatory changes caused by HSV latent infections, and if those changes were similar to alterations observed in the spinal cord of amyotrophic lateral sclerosis (ALS) patients. RESULTS: In infected spinal cords, we have observed a strong leukocyte infiltration and a severe alteration of microglia close to motor neurons. We have also analyzed ALS-related proteins: we have not found changes in TDP-43 and Fus in neurons, but interestingly, we have found decreased protein levels of C9orf72, of which coding gene is severely altered in some familial forms of ALS and is critical for microglia homeostasis. CONCLUSIONS: Latent infection of HSV in the spinal cord showed altered microglia and leukocyte infiltration. These inflammatory features resembled to those observed in the spinal cord of ALS patients. No changes mimicking ALS neuropathology, such as TDP-43 cytoplasmic inclusions, were found in infected spinal cords, but a decrease in protein levels of C9orf72 was observed. Then, further studies should be required to determine whether HSV-2 has a role in ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , C9orf72 Protein/metabolism , Herpes Genitalis/metabolism , Herpesvirus 2, Human/isolation & purification , Latent Infection/metabolism , Spinal Cord/metabolism , Amyotrophic Lateral Sclerosis/immunology , Animals , C9orf72 Protein/analysis , Disease Models, Animal , Female , Herpes Genitalis/immunology , Herpes Genitalis/pathology , Herpesvirus 2, Human/immunology , Latent Infection/immunology , Latent Infection/pathology , Mice , Mice, Inbred BALB C , Spinal Cord/pathology , Spinal Cord/virology , Vagina/immunology , Vagina/metabolism , Vagina/pathology , Vagina/virologyABSTRACT
A 37 year-old previously healthy man from Jamaica presented with 2-3 months of progressive trouble ambulating and incontinence. By 1 month prior to arrival he was wheelchair bound and unable to ambulate even with assistance. He started to wear a diaper for bladder and bowel incontinence. He also complained of painless numbness in his legs over the same period of time. His exam is notable for marked weakness and spasticity in his legs, with hyper-reflexia and clonus. He has a sensory level at the level of the umbilicus. An MRI shows a longitudinally extensive T2 signal change throughout the thoracic cord. His cerebrospinal fluid is mildly inflammatory. His HTLV-1 antibody test is reactive.
Subject(s)
HTLV-I Antibodies/urine , Nervous System Diseases/pathology , Spinal Cord Neoplasms/physiopathology , Urinary Incontinence/physiopathology , Adult , Humans , Jamaica , Male , Nervous System Diseases/physiopathology , Spinal Cord/virology , Urinary Incontinence/diagnosisABSTRACT
Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the central nervous system caused by JC virus (JCV) and is difficult to diagnose. We report on a male HIV-positive patient with PML finally diagnosed by 3 times lumbar punctures and 2 times brain biopsies. Negative results of JCV-PCR in cerebrospinal fluid (CSF) do not rule out the diagnosis of PML when clinical manifestations and neuroimaging features suspected PML. It is necessary to obtain new CSF and make repeat tests and even perform brain biopsy.
Subject(s)
Brain/pathology , HIV Infections/pathology , Leukoencephalopathy, Progressive Multifocal/pathology , Spinal Cord/pathology , Brain/diagnostic imaging , Brain/virology , Coinfection , DNA, Viral/genetics , Fatal Outcome , HIV/genetics , HIV/isolation & purification , HIV Infections/diagnostic imaging , HIV Infections/virology , Humans , JC Virus/genetics , JC Virus/isolation & purification , Leukoencephalopathy, Progressive Multifocal/diagnostic imaging , Leukoencephalopathy, Progressive Multifocal/virology , Magnetic Resonance Imaging , Male , Middle Aged , Spinal Cord/diagnostic imaging , Spinal Cord/virology , Spinal PunctureABSTRACT
Enterovirus (EV)-D68 has been associated with epidemics in the United Sates in 2014, 2016 and 2018. This study aims to identify potential viral virulence determinants. We found that neonatal type I interferon receptor knockout mice are susceptible to EV-D68 infection via intraperitoneal inoculation and were able to recapitulate the paralysis process observed in human disease. Among the EV-D68 strains tested, strain US/MO-14-18949 caused no observable disease in this mouse model, whereas the other strains caused paralysis and death. Sequence analysis revealed several conserved genetic changes among these virus strains: nucleotide positions 107 and 648 in the 5'-untranslated region (UTR); amino acid position 88 in VP3; 1, 148, 282 and 283 in VP1; 22 in 2A; 47 in 3A. A series of chimeric and point-mutated infectious clones were constructed to identify viral elements responsible for the distinct virulence. A single amino acid change from isoleucine to valine at position 88 in VP3 attenuated neurovirulence by reducing virus replication in the brain and spinal cord of infected mice.
Subject(s)
Capsid Proteins/genetics , Enterovirus D, Human/genetics , Enterovirus D, Human/pathogenicity , Enterovirus Infections/virology , 5' Untranslated Regions , Amino Acid Substitution , Animals , Brain/virology , Capsid Proteins/chemistry , Cell Line , Cell Line, Tumor , Disease Models, Animal , Enterovirus D, Human/physiology , Genes, Viral , Humans , Mice, Inbred C57BL , Mice, Knockout , Models, Molecular , Molecular Dynamics Simulation , Receptor, Interferon alpha-beta/genetics , Spinal Cord/virology , Virulence , Virus ReplicationABSTRACT
Human T-lymphotropic virus type 1 (HTLV-1) is associated with adult T cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is an inflammatory disease of the spinal cord and clinically characterized by progressive spastic paraparesis, urinary incontinence, and mild sensory disturbance. The interaction between the host immune response and HTLV-1-infected cells regulates the development of HAM/TSP. HTLV-1 preferentially infects CD4+ T cells and is maintained by proliferation of the infected T cells. HTLV-1-infected cells rarely express viral antigens in vivo; however, they easily express the antigens after short-term culture. Therefore, such virus-expressing cells may lead to activation and expansion of antigen-specific T cell responses. Infected T cells with HTLV-1 and HTLV-1-specific CD8+ cytotoxic T lymphocytes invade the central nervous system and produce various proinflammatory cytokines and chemokines, leading to neuronal damage and degeneration. Therefore, cellular immune responses to HTLV-1 have been considered to play important roles in disease development of HAM/TSP. Recent studies have clarified the viral strategy for persistence in the host through genetic and epigenetic changes by HTLV-1 and host immune responses including T cell function and differentiation. Newly developed animal models could provide the opportunity to uncover the precise pathogenesis and development of clinically effective treatment. Several molecular target drugs are undergoing clinical trials with promising efficacy. In this review, we summarize recent advances in the immunopathogenesis of HAM/TSP and discuss the perspectives of the research on this disease.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , Cytokines/immunology , Human T-lymphotropic virus 1/pathogenicity , Leukemia-Lymphoma, Adult T-Cell/immunology , Paraparesis, Tropical Spastic/immunology , Urinary Incontinence/immunology , Animals , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/virology , Cell Proliferation/drug effects , Cytokines/biosynthesis , Disease Models, Animal , Host-Pathogen Interactions/immunology , Human T-lymphotropic virus 1/drug effects , Human T-lymphotropic virus 1/immunology , Humans , Immunity, Cellular/drug effects , Immunologic Factors/therapeutic use , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Leukemia-Lymphoma, Adult T-Cell/pathology , Leukemia-Lymphoma, Adult T-Cell/virology , Lymphocyte Activation/drug effects , Neurons/drug effects , Neurons/immunology , Neurons/pathology , Neurons/virology , Neuroprotective Agents/therapeutic use , Paraparesis, Tropical Spastic/drug therapy , Paraparesis, Tropical Spastic/pathology , Paraparesis, Tropical Spastic/virology , Spinal Cord/drug effects , Spinal Cord/immunology , Spinal Cord/virology , T-Lymphocytes, Cytotoxic/drug effects , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/virology , Urinary Incontinence/drug therapy , Urinary Incontinence/pathology , Urinary Incontinence/virologyABSTRACT
In light of the present therapeutic situation in COVID-19, any measure to improve course and outcome of seriously affected individuals is of utmost importance. We recap here evidence that supports the use of human recombinant erythropoietin (EPO) for ameliorating course and outcome of seriously ill COVID-19 patients. This brief expert review grounds on available subject-relevant literature searched until May 14, 2020, including Medline, Google Scholar, and preprint servers. We delineate in brief sections, each introduced by a summary of respective COVID-19 references, how EPO may target a number of the gravest sequelae of these patients. EPO is expected to: (1) improve respiration at several levels including lung, brainstem, spinal cord and respiratory muscles; (2) counteract overshooting inflammation caused by cytokine storm/ inflammasome; (3) act neuroprotective and neuroregenerative in brain and peripheral nervous system. Based on this accumulating experimental and clinical evidence, we finally provide the research design for a double-blind placebo-controlled randomized clinical trial including severely affected patients, which is planned to start shortly.
Subject(s)
Betacoronavirus/pathogenicity , Coronavirus Infections/drug therapy , Cytokine Release Syndrome/prevention & control , Erythropoietin/therapeutic use , Neuroprotective Agents/therapeutic use , Pneumonia, Viral/drug therapy , Respiratory System Agents/therapeutic use , Brain Stem/drug effects , Brain Stem/immunology , Brain Stem/virology , COVID-19 , Coronavirus Infections/immunology , Coronavirus Infections/pathology , Coronavirus Infections/virology , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/pathology , Cytokine Release Syndrome/virology , Double-Blind Method , Humans , Lung/drug effects , Lung/immunology , Lung/virology , Pandemics , Phrenic Nerve/drug effects , Phrenic Nerve/immunology , Phrenic Nerve/virology , Pneumonia, Viral/immunology , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , Proof of Concept Study , Randomized Controlled Trials as Topic , Recombinant Proteins/therapeutic use , Respiratory Muscles/drug effects , Respiratory Muscles/immunology , Respiratory Muscles/virology , SARS-CoV-2 , Severity of Illness Index , Spinal Cord/drug effects , Spinal Cord/immunology , Spinal Cord/virologyABSTRACT
Usutu virus (USUV), an African mosquito-borne flavivirus closely related to West Nile virus, was first isolated in South Africa in 1959. USUV emerged in Europe two decades ago, causing notably massive mortality in Eurasian blackbirds. USUV is attracting increasing attention due to its potential for emergence and its rapid spread in Europe in recent years. Although mainly asymptomatic or responsible for mild clinical signs, USUV was recently described as being associated with neurological disorders in humans such as encephalitis and meningoencephalitis, highlighting the potential health threat posed by the virus. Despite this, USUV pathogenesis remains largely unexplored. The aim of this study was to evaluate USUV neuropathogenicity using in vivo and in vitro approaches. Our results indicate that USUV efficiently replicates in the murine central nervous system. Replication in the spinal cord and brain is associated with recruitment of inflammatory cells and the release of inflammatory molecules as well as induction of antiviral-responses without major modulation of blood-brain barrier integrity. Endothelial cells integrity is also maintained in a human model of the blood-brain barrier despite USUV replication and release of pro-inflammatory cytokines. Furthermore, USUV-inoculated mice developed major ocular defects associated with inflammation. Moreover, USUV efficiently replicates in human retinal pigment epithelium. Our results will help to better characterize the physiopathology related to USUV infection in order to anticipate the potential threat of USUV emergence.
Subject(s)
Flavivirus/pathogenicity , Models, Biological , Nervous System/virology , Animals , Brain/virology , Disease Models, Animal , Endothelial Cells/virology , Epithelial Cells/virology , Flavivirus/growth & development , Humans , Mice , Pigment Epithelium of Eye/virology , Spinal Cord/virologyABSTRACT
Usutu virus (USUV) is a mosquito-borne flavivirus that shares many similarities with the closely related West Nile virus (WNV) in terms of ecology and clinical manifestations. Initially distributed in Africa, USUV emerged in Italy in 1996 and managed to co-circulate with WNV in many European countries in a similar mosquito-bird life cycle. The rapid geographic spread of USUV, the seasonal mass mortalities it causes in the European avifauna, and the increasing number of infections with neurological disease both in healthy and immunocompromised humans has stimulated interest in infection studies to delineate USUV pathogenesis. Here, we assessed the pathogenicity of two USUV isolates from a recent Belgian outbreak in immunocompetent mice. The intradermal injection of USUV gave rise to disorientation and paraplegia and was associated with neuronal death in the brain and spinal cord in a single mouse. Intranasal inoculation of USUV could also establish the infection; viral RNA was detected in the brain 15 days post-infection. Overall, this pilot study probes the suitability of this murine model for the study of USUV neuroinvasiveness and the possibility of direct transmission in mammals.
Subject(s)
Disease Susceptibility/pathology , Disease Susceptibility/virology , Flavivirus Infections/pathology , Flavivirus/pathogenicity , Animals , Belgium , Birds/virology , Brain/virology , Disease Models, Animal , Female , Flavivirus/classification , Flavivirus Infections/virology , Immunocompetence , Mice , Pilot Projects , RNA, Viral/analysis , Spinal Cord/virologyABSTRACT
Human immunodeficiency virus (HIV)-related neuropathic pain includes HIV-induced neuropathic pain (HNP) and antiretroviral therapy-induced neuropathic pain (ART-NP). A significant amount of evidence from the past few years has shown that the development of HIV-related neuropathic pain is closely related to the activation of the Wnt signaling pathway in the spinal cord. This review summarizes the function of the spinal Wnt signaling pathway in HIV-induced neuropathic pain, focusing on the role of the spinal Wnt signaling pathway in HNP, and provides a theoretical basis for further studies and the exploration of new target drugs.
Subject(s)
HIV Infections/metabolism , Neuralgia/metabolism , Neuralgia/virology , Spinal Cord/metabolism , Wnt Signaling Pathway/physiology , Animals , Disease Models, Animal , Drug Development/methods , HIV Infections/virology , Humans , Spinal Cord/virologyABSTRACT
Enterovirus 71 (EV71) is a positive single-stranded RNA (ssRNA) virus from the enterovirus genus of Picornaviridae family and causes diseases ranged from the mild disease of hand, foot and mouth disease (HFMD) to the severe disease of neurological involvement in young children. TLR7 is an intracellular pattern recognition receptor (PRR) recognizing viral ssRNA. In this study, we investigated the role of TLR7 in EV71 infection in mouse pups (10-12 days old) and found that wild-type (WT) and TLR7 knock-out (TLR7KO) mice infected with EV71 showed similar limb paralysis at the onset and peak of the disease, comparable loss of motor neurons, and similar levels of antiviral molecules in the spinal cord. These results suggest that TLR7 is not the absolute PRR for EV71 in the spinal cord. Interestingly, TLR7KO mice infected with EV71 exhibited significantly delayed recovery from limb paralysis compared with WT mice. TLR7KO mice infected with EV71 showed significantly decreased levels of IgM and IgG2, important antibodies for antiviral humoral immunity. Furthermore, TLR7KO mice infected with EV71 showed a decrease of germinal center B cells in the spleen compared with WT mice. Altogether, our study suggests that TLR7 plays a critical role in anti-viral humoral immunity rather than in being a PRR in the spinal cord during EV71 infection in young mice.
Subject(s)
Enterovirus A, Human/immunology , Enterovirus Infections/immunology , Immunity, Humoral , Motor Neurons/metabolism , Spinal Cord/metabolism , Toll-Like Receptor 7/metabolism , Animals , Astrocytes/metabolism , B-Lymphocytes/immunology , Cytokines/metabolism , Enterovirus Infections/genetics , Enterovirus Infections/metabolism , Enterovirus Infections/virology , Germinal Center/immunology , Germinal Center/virology , Immunoglobulin G/immunology , Immunoglobulin M/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Microglia/metabolism , Motor Neurons/pathology , Motor Neurons/virology , Oligodendroglia/metabolism , Proteome/genetics , Proteome/metabolism , Receptors, IgG/metabolism , Spinal Cord/virology , Spleen/immunology , Spleen/virology , Toll-Like Receptor 7/geneticsABSTRACT
Zika virus (ZIKV) infection during pregnancy has been causally linked to a constellation of neurodevelopmental deformities in the fetus resulting in a disease termed congenital Zika syndrome (CZS). Here we detail how ZIKV infection produces extensive neuropathology in the developing mouse brain and spinal cord of both sexes. Surprisingly, neuropathology differs depending on viral strain with a French Polynesian isolate producing primarily excitotoxicity and a Brazilian isolate being almost exclusively apoptotic but occurring over a prolonged period that is more likely to produce severe hypoplasia. We also show exposure can produce a characteristic pattern of infection that mirrors neuropathology and ultimately results in gross morphological deformities strikingly similar to CZS. This research provides a valuable mouse model mirroring the clinical course of disease that can be used to test potential therapies to improve treatment and gain a better understanding of the disabilities associated with CZS.SIGNIFICANCE STATEMENT Zika virus (ZIKV) infection during pregnancy has been causally linked to a constellation of neurodevelopmental deformities in the fetus resulting in a disease termed congenital Zika syndrome. Despite its devastating effects, very little is known about how ZIKV infection produces fetal neuropathology. Here we detail the temporal progression of ZIKV infection in the mouse brain and spinal cord resulting in massive neurodegeneration of infected regions. We also report a ZIKV strain from a region of Brazil with high levels of microcephaly (abnormally small head circumference) produces particularly devastating neuropathology.
Subject(s)
Brain/virology , Neurons/virology , Spinal Cord/virology , Zika Virus Infection/pathology , Zika Virus Infection/virology , Animals , Animals, Newborn , Apoptosis , Brain/growth & development , Brain/pathology , Female , Male , Mice, Inbred C57BL , Neurons/pathology , Spinal Cord/growth & development , Spinal Cord/pathology , Zika Virus/pathogenicityABSTRACT
Prior work demonstrated that epithelial V-like antigen (EVA), a cell surface adhesion molecule, is expressed in B lymphocytes and is necessary for the efficacy of anti-alpha4 integrin treatment of experimental autoimmune encephalomyelitis (EAE), the mouse model of human multiple sclerosis. EVA deficiency is associated with a severe clinical phenotype of EAE in the presence or absence of treatment. Histological analysis revealed enhanced B cell-mediated autoimmunity and deposition of antibody and complement within the brain and spinal cord. Here our goal was to determine the molecular mechanism of EVA regulation of B lymphocyte function. Analysis of bone marrow from MOG-immunized mice revealed increased expansion of CD11c+ B cells in EVA-deficient mice as compared to wild type controls. In vitro studies of mouse bone marrow B lymphocytes revealed enhanced proliferation of the CD11c+ population in response to the Tlr7/8 agonist R848. An increase in R848-induced proliferation of CD11c+ B cells was also seen in vitro in Daudi cells, a human B cell line, following knockdown of the mpzl2 gene that encodes EVA. These mechanisms were characterized further by global expression analysis of bone marrow from immunized EVA-deficient and wild type control mice. These data revealed increased expression of B cell associated genes and decreased expression of the anti-viral oligoadenylate synthase genes, Oas1 and Oas2, in the knockout condition. In Daudi cells, R848 treatment induced an increase in Oas2 expression in control cells that was not observed in EVA-deficient cells. EVA deficiency also was associated with increased transcription of an Epstein-Barr virus gene during lytic replication. These results suggest EVA expression and signaling prevent expansion of CD11c+ B lymphocytes, a cellular phenotype associated with autoimmunity, increase expression of anti-viral oligoadenylate synthase genes, and reduce replication of a DNA virus.
Subject(s)
Antiviral Agents/immunology , B-Lymphocytes/immunology , CD11c Antigen/immunology , Animals , Autoimmunity/immunology , B-Lymphocytes/virology , Bone Marrow/immunology , Bone Marrow/virology , Brain/immunology , Brain/virology , Cell Adhesion Molecules/immunology , Cell Proliferation/physiology , Cells, Cultured , Encephalomyelitis, Autoimmune, Experimental/immunology , Encephalomyelitis, Autoimmune, Experimental/virology , Herpesvirus 4, Human/immunology , Humans , Mice , Mice, Inbred C57BL , Mice, Knockout , Multiple Sclerosis/immunology , Multiple Sclerosis/virology , Signal Transduction/immunology , Spinal Cord/immunology , Spinal Cord/virologyABSTRACT
Coordination of activity of external urethral sphincter (EUS) striated muscle and bladder (BL) smooth muscle is essential for efficient voiding. In this study we examined the morphological and electrophysiological properties of neurons in the L3/L4 spinal cord (SC) that are likely to have an important role in EUS-BL coordination in rats. EUS-related SC neurons were identified by retrograde transsynaptic tracing following injection of pseudorabies virus (PRV) co-expressing fluorescent markers into the EUS of P18-P20 male rats. Tracing revealed not only EUS motoneurons in L6/S1 but also interneurons in lamina X of the L6/S1 and L3/L4 SC. Physiological properties of fluorescently labeled neurons were assessed during whole-cell recordings in SC slices followed by reconstruction of biocytin-filled neurons. Reconstructions of neuronal processes from transverse or longitudinal slices showed that some L3/L4 neurons have axons projecting toward and into the ventro-medial funiculus (VMf) where axons extended caudally. Other neurons had axons projecting within laminae X and VII. Dendrites of L3/L4 neurons were distributed within laminae X and VII. The majority of L3/L4 neurons exhibited tonic firing in response to depolarizing currents. In transverse slices focal electrical stimulation (FES) in the VMf or in laminae X and VII elicited antidromic axonal spikes and/or excitatory synaptic responses in L3/L4 neurons; while in longitudinal slices FES elicited excitatory synaptic inputs from sites up to 400⯵m along the central canal. Inhibitory inputs were rarely observed. These data suggest that L3/L4 EUS-related circuitry consists of at least two neuronal populations: segmental interneurons and propriospinal neurons projecting to L6/S1.