scholarly journals The Interferon-Stimulated GeneIfitm3Restricts West Nile Virus Infection and Pathogenesis

2016 ◽  
Vol 90 (18) ◽  
pp. 8212-8225 ◽  
Author(s):  
Matthew J. Gorman ◽  
Subhajit Poddar ◽  
Michael Farzan ◽  
Michael S. Diamond
Keyword(s):  
Central Nervous System ◽  
Cell Culture ◽  
T Cells ◽  
Nervous System ◽  
West Nile Virus ◽  
Transmembrane Protein ◽  
Viral Pathogenesis ◽  
West Nile ◽  
The Brain

ABSTRACTThe interferon-induced transmembrane protein (IFITM) family of proteins inhibit infection of several different enveloped viruses in cell culture by virtue of their ability to restrict entry and fusion from late endosomes. As few studies have evaluated the importance ofIfitm3 in vivoin restricting viral pathogenesis, we investigated its significance as an antiviral gene against West Nile virus (WNV), an encephalitic flavivirus, in cells and mice.Ifitm3−/−mice were more vulnerable to lethal WNV infection, and this was associated with greater virus accumulation in peripheral organs and central nervous system tissues. As no difference in viral burden in the brain or spinal cord was observed after direct intracranial inoculation, Ifitm3 likely functions as an antiviral protein in nonneuronal cells. Consistent with this,Ifitm3−/−fibroblasts but not dendritic cells resulted in higher yields of WNV in multistep growth analyses. Moreover, transcomplementation experiments showed that Ifitm3 inhibited WNV infection independently of Ifitm1, Ifitm2, Ifitm5, and Ifitm6. Beyond a direct effect on viral infection in cells, analysis of the immune response in WNV-infectedIfitm3−/−mice showed decreases in the total number of B cells, CD4+T cells, and antigen-specific CD8+T cells. Finally, bone marrow chimera experiments demonstrated that Ifitm3 functioned in both radioresistant and radiosensitive cells, as higher levels of WNV were observed in the brain only when Ifitm3 was absent from both compartments. Our analyses suggest that Ifitm3 restricts WNV pathogenesis likely through multiple mechanisms, including the direct control of infection in subsets of cells.IMPORTANCEAs part of the mammalian host response to viral infections, hundreds of interferon-stimulated genes (ISGs) are induced. The inhibitory activity of individual ISGs varies depending on the specific cell type and viral pathogen. Among ISGs, the genes encoding interferon-induced transmembrane protein (IFITM) have been reported to inhibit multiple families of viruses in cell culture. However, few reports have evaluated the impact ofIFITMgenes on viral pathogenesisin vivo. In this study, we characterized the antiviral activity of Ifitm3 against West Nile virus (WNV), an encephalitic flavivirus, using mice with a targeted gene deletion ofIfitm3. Based on extensive virological and immunological analyses, we determined that Ifitm3 protects mice from WNV-induced mortality by restricting virus accumulation in peripheral organs and, subsequently, in central nervous system tissues. Our data suggest that Ifitm3 restricts WNV pathogenesis by multiple mechanisms and functions in part by controlling infection in different cell types.

scholarly journals Role of CD8+ T Cells in Control of West Nile Virus Infection

2004 ◽  
Vol 78 (15) ◽  
pp. 8312-8321 ◽  
Author(s):  
Bimmi Shrestha ◽  
Michael S. Diamond
Keyword(s):  
Central Nervous System ◽  
T Cells ◽  
Nervous System ◽  
West Nile Virus ◽  
Immunoglobulin M ◽  
Target Cells ◽  
West Nile ◽  
Class I Mhc ◽  
Increased Risk

ABSTRACT Infection with West Nile virus (WNV) causes fatal encephalitis more frequently in immunocompromised humans than in those with a healthy immune system. Although a complete understanding of this increased risk remains unclear, experiments with mice have begun to define how different components of the adaptive and innate immune response function to limit infection. Previously, we demonstrated that components of humoral immunity, particularly immunoglobulin M (IgM) and IgG, have critical roles in preventing dissemination of WNV infection to the central nervous system. In this study, we addressed the function of CD8+ T cells in controlling WNV infection. Mice that lacked CD8+ T cells or classical class Ia major histocompatibility complex (MHC) antigens had higher central nervous system viral burdens and increased mortality rates after infection with a low-passage-number WNV isolate. In contrast, an absence of CD8+ T cells had no effect on the qualitative or quantitative antibody response and did not alter the kinetics or magnitude of viremia. In the subset of CD8+-T-cell-deficient mice that survived initial WNV challenge, infectious virus was recovered from central nervous system compartments for several weeks. Primary or memory CD8+ T cells that were generated in vivo efficiently killed target cells that displayed WNV antigens in a class I MHC-restricted manner. Collectively, our experiments suggest that, while specific antibody is responsible for terminating viremia, CD8+ T cells have an important function in clearing infection from tissues and preventing viral persistence.

scholarly journals The Innate Immune Adaptor Molecule MyD88 Restricts West Nile Virus Replication and Spread in Neurons of the Central Nervous System

2010 ◽  
Vol 84 (23) ◽  
pp. 12125-12138 ◽  
Author(s):  
Kristy J. Szretter ◽  
Stephane Daffis ◽  
Jigisha Patel ◽  
Mehul S. Suthar ◽  
Robyn S. Klein ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
West Nile Virus ◽  
Virus Replication ◽  
Independent Effect ◽  
Type I ◽  
Rna Helicases ◽  
West Nile ◽  
The Central Nervous System ◽  
The Brain

ABSTRACT Type I interferons (IFN-α/β) control viral infection by triggering the expression of genes that restrict transcription, translation, replication, and assembly. Many viruses induce IFN responses after recognition by cytoplasmic or endosomal RNA sensors (RIG-I-like RNA helicases [RLR] and Toll-like receptors [TLR]), which signal through the cognate adaptor signaling molecules IPS-1, TRIF, and MyD88. Recent studies have demonstrated that IPS-1-dependent induction of IFN-α/β downstream of RLR recognition restricts West Nile virus (WNV) infection in many cell types, whereas TRIF-dependent TLR3 signaling limits WNV replication in neurons. Here, we examined the contribution of MyD88 signaling to the control of WNV by evaluating IFN induction and virus replication in genetically deficient cells and mice. MyD88 − / − mice showed increased lethality after WNV infection and elevated viral burden primarily in the brain, even though little effect on the systemic type I IFN response was observed. Intracranial inoculation studies corroborated these findings, as WNV spread more rapidly in the central nervous system of MyD88 − / − mice, and this phenotype preceded the recruitment of inflammatory leukocytes. In vitro, increased WNV replication was observed in MyD88 − / − macrophages and subsets of neurons but not in myeloid dendritic cells. MyD88 had an independent effect on recruitment of monocyte-derived macrophages and T cells into the brain that was associated with blunted induction of the chemokines that attract leukocytes. Our experiments suggest that MyD88 restricts WNV by inhibiting replication in subsets of cells and modulating expression of chemokines that regulate immune cell migration into the central nervous system.

scholarly journals The Interferon-Stimulated GeneIfi27l2aRestricts West Nile Virus Infection and Pathogenesis in a Cell-Type- and Region-Specific Manner

2015 ◽  
Vol 90 (5) ◽  
pp. 2600-2615 ◽  
Author(s):  
Tiffany M. Lucas ◽  
Justin M. Richner ◽  
Michael S. Diamond
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Cell Culture ◽  
Nervous System ◽  
West Nile Virus ◽  
Cell Type ◽  
West Nile ◽  
Specific Manner ◽  
A Cell ◽  
The Central Nervous System

ABSTRACTThe mammalian host responds to viral infections by inducing expression of hundreds of interferon-stimulated genes (ISGs). While the functional significance of many ISGs has yet to be determined, their cell type and temporal nature of expression suggest unique activities against specific pathogens. Using a combination of ectopic expression and gene silencing approaches in cell culture, we previously identifiedIfi27l2aas a candidate antiviral ISG within neuronal subsets of the central nervous system (CNS) that restricts infection by West Nile virus (WNV), an encephalitic flavivirus of global concern. To investigate the physiological relevance of Ifi27l2a in the context of viral infection, we generatedIfi27l2a−/−mice. Although adult mice lackingIfi27l2awere more vulnerable to lethal WNV infection, the viral burden was greater only within the CNS, particularly in the brain stem, cerebellum, and spinal cord. Within neurons of the cerebellum and brain stem, in the context of WNV infection, a deficiency of Ifi27l2a was associated with less cell death, which likely contributed to sustained viral replication and higher titers in these regions. Infection studies in a primary cell culture revealed thatIfi27l2a−/−cerebellar granule cell neurons and macrophages but not cerebral cortical neurons, embryonic fibroblasts, or dendritic cells sustained higher levels of WNV infection than wild-type cells and that this difference was greater under conditions of beta interferon (IFN-β) pretreatment. Collectively, these findings suggest that Ifi27l2a has an antiviral phenotype in subsets of cells and that at least some ISGs have specific inhibitory functions in restricted tissues.IMPORTANCEThe interferon-stimulatedIfi27l2agene is expressed differentially within the central nervous system upon interferon stimulation or viral infection. Prior studies in cell culture suggested an antiviral role for Ifi27l2a during infection by West Nile virus (WNV). To characterize its antiviral activityin vivo, we generated mice with a targeted gene deletion ofIfi27l2a. Based on extensive virological analyses, we determined that Ifi27l2a protects mice from WNV-induced mortality by contributing to the control of infection of the hindbrain and spinal cord, possibly by regulating cell death of neurons. This antiviral activity was validated in granule cell neurons derived from the cerebellum and in macrophages but was not observed in other cell types. Collectively, these data suggest that Ifi27l2a contributes to innate immune restriction of WNV in a cell-type- and tissue-specific manner.

scholarly journals West Nile Virus Induced Cell Death in the Central Nervous System

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 215 ◽  
Author(s):  
Peng ◽  
Wang
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
West Nile Virus ◽  
Neuronal Damage ◽  
Acute Infection ◽  
The United States ◽  
West Nile ◽  
The Central Nervous System

West Nile virus (WNV), a mosquito-borne, single-stranded flavivirus, has caused annual outbreaks of viral encephalitis in the United States since 1999. The virus induces acute infection with a clinical spectrum ranging from a mild flu-like febrile symptom to more severe neuroinvasive conditions, including meningitis, encephalitis, acute flaccid paralysis, and death. Some WNV convalescent patients also developed long-term neurological sequelae. Neither the treatment of WNV infection nor an approved vaccine is currently available for humans. Neuronal death in the central nervous system (CNS) is a hallmark of WNV-induced meningitis and encephalitis. However, the underlying mechanisms of WNV-induced neuronal damage are not well understood. In this review, we discuss current findings from studies of WNV infection in vitro in the CNS resident cells and the in vivo animal models, and provide insights into WNV-induced neuropathogenesis.

scholarly journals Neuronal CXCL10 Directs CD8+ T-Cell Recruitment and Control of West Nile Virus Encephalitis

2005 ◽  
Vol 79 (17) ◽  
pp. 11457-11466 ◽  
Author(s):  
Robyn S. Klein ◽  
Eugene Lin ◽  
Bo Zhang ◽  
Andrew D. Luster ◽  
Judy Tollett ◽  
...  
Keyword(s):  
Central Nervous System ◽  
T Cells ◽  
Nervous System ◽  
West Nile Virus ◽  
T Cell ◽  
Cell Trafficking ◽  
New Paradigm ◽  
West Nile ◽  
West Nile Virus Encephalitis ◽  
The Central Nervous System

ABSTRACT The activation and entry of antigen-specific CD8+ T cells into the central nervous system is an essential step towards clearance of West Nile virus (WNV) from infected neurons. The molecular signals responsible for the directed migration of virus-specific T cells and their cellular sources are presently unknown. Here we demonstrate that in response to WNV infection, neurons secrete the chemokine CXCL10, which recruits effector T cells via the chemokine receptor CXCR3. Neutralization or a genetic deficiency of CXCL10 leads to a decrease in CXCR3+ CD8+ T-cell trafficking, an increase in viral burden in the brain, and enhanced morbidity and mortality. These data support a new paradigm in chemokine neurobiology, as neurons are not generally considered to generate antiviral immune responses, and CXCL10 may represent a novel neuroprotective agent in response to WNV infection in the central nervous system.

scholarly journals Fas Ligand Interactions Contribute to CD8+ T-Cell-Mediated Control of West Nile Virus Infection in the Central Nervous System

2007 ◽  
Vol 81 (21) ◽  
pp. 11749-11757 ◽  
Author(s):  
Bimmi Shrestha ◽  
Michael S. Diamond
Keyword(s):  
Central Nervous System ◽  
T Cells ◽  
Nervous System ◽  
West Nile Virus ◽  
T Cell ◽  
Fas Ligand ◽  
Lymphoid Tissues ◽  
Control Mechanisms ◽  
West Nile ◽  
Specific Priming

ABSTRACT West Nile virus (WNV) is a neurotropic flavivirus that causes encephalitis, most frequently in elderly and immunocompromised humans. Previous studies demonstrated that CD8+ T cells utilize perforin-dependent cytolytic mechanisms to limit WNV infection. Nonetheless, the phenotype of perforin-deficient CD8+ T cells was not as severe as that of an absence of CD8+ T cells, suggesting additional effector control mechanisms. In this study, we evaluated the contribution of Fas-Fas ligand (FasL) interactions to CD8+ T-cell-mediated control of WNV infection. Notably, the cell death receptor Fas was strongly upregulated on neurons in culture and in vivo after WNV infection. gld mice that were functionally deficient in FasL expression showed increased susceptibility to lethal WNV infection. Although antigen-specific priming of CD8+ T cells in peripheral lymphoid tissues was normal in gld mice, increased central nervous system (CNS) viral burdens and delayed clearance were observed. Moreover, the adoptive transfer of WNV-primed wild-type but not gld CD8+ T cells to recipient CD8−/− or gld mice efficiently limited infection in the CNS and enhanced survival rates. Overall, our data suggest that CD8+ T cells also utilize FasL effector mechanisms to contain WNV infection in Fas-expressing neurons in the CNS.

scholarly journals A Case of Central Nervous System Infection Due to West Nile Virus Lineage-1 in Ankara Province, Turkey

2013 ◽  
pp. 164-172 ◽  
Author(s):  
Murat ÖCAL ◽  
Halil ÖNDER ◽  
Ethem M. ARSAVA ◽  
Şehnaz ALP ◽  
Aykut ÖZKUL ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
West Nile Virus ◽  
Central Nervous System Infection ◽  
West Nile

scholarly journals West Nile Virus Central Nervous System Infection in Patients Treated With Rituximab: Implications for Diagnosis and Prognosis, With a Review of Literature

2015 ◽  
Vol 2 (4) ◽  
Author(s):  
Sejal Morjaria ◽  
Esther Arguello ◽  
Ying Taur ◽  
Kent Sepkowitz ◽  
Vaios Hatzoglou ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
West Nile Virus ◽  
Central Nervous System Infection ◽  
Central Nervous System Disease ◽  
Immunocompromised Patients ◽  
Review Of Literature ◽  
West Nile ◽  
Diagnosis And Prognosis ◽  
System Disease

Abstract The spectrum of West Nile virus (WNV) infection continues to be elucidated. Many cases of WNV are asymptomatic; however, in immunocompromised patients, symptoms are more likely to be severe. We describe fatal WNV central nervous system disease in lymphoma patients who received rituximab, blunting the inflammatory response and complicating diagnosis.

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