scholarly journals Chemokine Receptor Ccr7 Restricts Fatal West Nile Virus Encephalitis

2017 ◽  
Vol 91 (10) ◽  
Author(s):  
Susana V. Bardina ◽  
Julia A. Brown ◽  
Daniela Michlmayr ◽  
Kevin W. Hoffman ◽  
Janet Sum ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Lymph Node ◽  
West Nile Virus ◽  
West Nile ◽  
Viral Loads ◽  
West Nile Virus Encephalitis ◽  
Draining Lymph Node ◽  
The Brain ◽  
Deficient Mice

ABSTRACT West Nile virus (WNV) is a mosquito-transmitted flavivirus that can cause debilitating encephalitis. To delineate the mechanisms behind this pathology, we studied Ccr7-deficient mice, which afforded us the capacity to study infection in mice with disrupted peripheral cellular trafficking events. The loss of Ccr7 resulted in an immediate pan-leukocytosis that remained elevated throughout the infection. This leukocytosis resulted in a significant enhancement of leukocyte accumulation within the central nervous system (CNS). Despite an excess of virus-specific T cells in the CNS, Ccr7-deficient mice had significantly higher CNS viral loads and mortality rates than wild-type animals. Mechanistically, the elevated trafficking of infected myeloid cells into the brain in Ccr7-deficient mice resulted in increased levels of WNV in the CNS, thereby effectively contributing to neuroinflammation and lowering viral clearance. Combined, our experiments suggest that during WNV infection, Ccr7 is a gatekeeper for nonspecific viral transference to the brain. IMPORTANCE In this study, we show that Ccr7 is required for the sufficient migration of dendritic cells and T cells into the draining lymph node immediately following infection and for the restriction of leukocyte migration into the brain. Further, the severe loss of dendritic cells in the draining lymph node had no impact on viral replication in this organ, suggesting that WNV may migrate from the skin into the lymph node through another mechanism. Most importantly, we found that the loss of Ccr7 results in a significant leukocytosis, leading to hypercellularity within the CNS, where monocytes/macrophages contribute to CNS viremia, neuroinflammation, and increased mortality. Together, our data point to Ccr7 as a critical host defense restriction factor limiting neuroinflammation during acute viral infection.

scholarly journals CD8+ T Cells Mediate Recovery andImmunopathology in West Nile VirusEncephalitis

2003 ◽  
Vol 77 (24) ◽  
pp. 13323-13334 ◽  
Author(s):  
Yang Wang ◽  
Mario Lobigs ◽  
Eva Lee ◽  
Arno Müllbacher
Keyword(s):  
T Cells ◽  
Dose Group ◽  
Low Dose ◽  
Neuronal Degeneration ◽  
High Dose ◽  
West Nile ◽  
Activation Markers ◽  
High Doses ◽  
The Brain ◽  
Deficient Mice

ABSTRACT C57BL/6J mice infected intravenously with the Sarafend strain of West Nile virus (WNV) develop a characteristic central nervous system (CNS) disease, including an acute inflammatory reaction. Dose response studies indicate two distinct kinetics of mortality. At high doses of infection (108 PFU), direct infection of the brain occurred within 24 h, resulting in 100% mortality with a 6-day mean survival time (MST), and there was minimal destruction of neural tissue. A low dose (103 PFU) of infection resulted in 27% mortality (MST, 11 days), and virus could be detected in the CNS 7 days postinfection (p.i.). Virus was present in the hypogastric lymph nodes and spleens at days 4 to 7 p.i. Histology of the brains revealed neuronal degeneration and inflammation within leptomeninges and brain parenchyma. Inflammatory cell infiltration was detectable in brains from day 4 p.i. onward in the high-dose group and from day 7 p.i. in the low-dose group, with the severity of infiltration increasing over time. The cellular infiltrates in brain consisted predominantly of CD8+, but not CD4+, T cells. CD8+ T cells in the brain and the spleen expressed the activation markers CD69 early and expressed CD25 at later time points. CD8+ T-cell-deficient mice infected with 103 PFU of WNV showed increased mortalities but prolonged MST and early infection of the CNS compared to wild-type mice. Using high doses of virus in CD8-deficient mice leads to increased survival. These results provide evidence that CD8+ T cells are involved in both recovery and immunopathology in WNV infection.

scholarly journals MAVS Expressed by Hematopoietic Cells Is Critical for Control of West Nile Virus Infection and Pathogenesis

2016 ◽  
Vol 90 (16) ◽  
pp. 7098-7108 ◽  
Author(s):  
Jincun Zhao ◽  
Rahul Vijay ◽  
Jingxian Zhao ◽  
Michael Gale ◽  
Michael S. Diamond ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
West Nile Virus ◽  
Hematopoietic Cells ◽  
The United States ◽  
Innate Immune ◽  
Target Cells ◽  
West Nile ◽  
Adaptor Molecule ◽  
The Brain

ABSTRACTWest Nile virus (WNV) is the most important cause of epidemic encephalitis in North America. Innate immune responses, which are critical for control of WNV infection, are initiated by signaling through pathogen recognition receptors, RIG-I and MDA5, and their downstream adaptor molecule, MAVS. Here, we show that a deficiency of MAVS in hematopoietic cells resulted in increased mortality and delayed WNV clearance from the brain. InMavs−/−mice, a dysregulated immune response was detected, characterized by a massive influx of macrophages and virus-specific T cells into the infected brain. These T cells were polyfunctional and lysed peptide-pulsed target cellsin vitro. However, virus-specific T cells in the brains of infectedMavs−/−mice exhibited lower functional avidity than those in wild-type animals, and even virus-specific memory T cells generated by prior immunization could not protectMavs−/−mice from WNV-induced lethal disease. Concomitant with ineffective virus clearance, macrophage numbers were increased in theMavs−/−brain, and both macrophages and microglia exhibited an activated phenotype. Microarray analyses of leukocytes in the infectedMavs−/−brain showed a preferential expression of genes associated with activation and inflammation. Together, these results demonstrate a critical role for MAVS in hematopoietic cells in augmenting the kinetics of WNV clearance and thereby preventing a dysregulated and pathogenic immune response.IMPORTANCEWest Nile virus (WNV) is the most important cause of mosquito-transmitted encephalitis in the United States. The innate immune response is known to be critical for protection in infected mice. Here, we show that expression of MAVS, a key adaptor molecule in the RIG-I-like receptor RNA-sensing pathway, in hematopoietic cells is critical for protection from lethal WNV infection. In the absence of MAVS, there is a massive infiltration of myeloid cells and virus-specific T cells into the brain and overexuberant production of proinflammatory cytokines. These results demonstrate the important role that MAVS expression in hematopoietic cells has in regulating the inflammatory response in the WNV-infected brain.

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 Dynamics of Tissue-Specific CD8+ T Cell Responses during West Nile Virus Infection

2018 ◽  
Vol 92 (10) ◽  
pp. e00014-18 ◽  
Author(s):  
Renan Aguilar-Valenzuela ◽  
Jason Netland ◽  
Young-Jin Seo ◽  
Michael J. Bevan ◽  
Arash Grakoui ◽  
...  
Keyword(s):  
T Cells ◽  
West Nile Virus ◽  
T Cell ◽  
Immunodominant Epitope ◽  
West Nile ◽  
Cell Responses ◽  
Immunological Mechanisms ◽  
The Brain ◽  
Ns4b Protein

ABSTRACT The mouse model of West Nile virus (WNV), which is a leading cause of mosquito-borne encephalitis worldwide, has provided fundamental insights into the host and viral factors that regulate viral pathogenesis and infection outcome. In particular, CD8+ T cells are critical for controlling WNV replication and promoting protection against infection. Here, we present the characterization of a T cell receptor (TCR)-transgenic mouse with specificity for the immunodominant epitope in the WNV NS4B protein (here referred to as transgenic WNV-I mice). Using an adoptive-transfer model, we found that WNV-I CD8+ T cells behave similarly to endogenous CD8+ T cell responses, with an expansion phase in the periphery beginning around day 7 postinfection (p.i.) followed by a contraction phase through day 15 p.i. Through the use of in vivo intravascular immune cell staining, we determined the kinetics, expansion, and differentiation into effector and memory subsets of WNV-I CD8+ T cells within the spleen and brain. We found that red-pulp WNV-I CD8+ T cells were more effector-like than white-pulp WNV-I CD8+ T cells, which displayed increased differentiation into memory precursor cells. Within the central nervous system (CNS), we found that WNV-I CD8+ T cells were polyfunctional (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]), displayed tissue-resident characteristics (CD69+ and CD103+), persisted in the brain through day 15 p.i., and reduced the viral burden within the brain. The use of these TCR-transgenic WNV-I mice provides a new resource to dissect the immunological mechanisms of CD8+ T cell-mediated protection during WNV infection. IMPORTANCE West Nile Virus (WNV) is the leading cause of mosquito-borne encephalitis worldwide. There are currently no approved therapeutics or vaccines for use in humans to treat or prevent WNV infection. CD8+ T cells are critical for controlling WNV replication and protecting against infection. Here, we present a comprehensive characterization of a novel TCR-transgenic mouse with specificity for the immunodominant epitope in the WNV NS4B protein. In this study, we determine the kinetics, proliferation, differentiation into effector and memory subsets, homing, and clearance of WNV in the CNS. Our findings provide a new resource to dissect the immunological mechanisms of CD8+ T cell-mediated protection during WNV infection.

scholarly journals γδd T cells promote the maturation of dendritic cells during West Nile virus infection

2010 ◽  
Vol 59 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Hao Fang ◽  
Thomas Welte ◽  
Xin Zheng ◽  
Gwong-Jen J. Chang ◽  
Michael R. Holbrook ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
West Nile Virus ◽  
Virus Infection ◽  
West Nile Virus Infection ◽  
West Nile

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 CD8+ T Cells Require Perforin To Clear West Nile Virus from Infected Neurons

2006 ◽  
Vol 80 (1) ◽  
pp. 119-129 ◽  
Author(s):  
Bimmi Shrestha ◽  
Melanie A. Samuel ◽  
Michael S. Diamond
Keyword(s):  
New York ◽  
T Cells ◽  
West Nile Virus ◽  
Fas Ligand ◽  
Wild Type ◽  
West Nile ◽  
Necrosis Factor Alpha ◽  
Mediated Effects ◽  
The Central Nervous System ◽  
Deficient Mice

ABSTRACT Injury to neurons after West Nile virus (WNV) infection is believed to occur because of viral and host immune-mediated effects. Previously, we demonstrated that CD8+ T cells are required for the resolution of WNV infection in the central nervous system (CNS). CD8+ T cells can control infection by producing antiviral cytokines (e.g., gamma interferon or tumor necrosis factor alpha) or by triggering death of infected cells through perforin- or Fas ligand-dependent pathways. Here, we directly evaluated the role of perforin in controlling infection of a lineage I New York isolate of WNV in mice. A genetic deficiency of perforin molecules resulted in higher viral burden in the CNS and increased mortality after WNV infection. In the few perforin-deficient mice that survived initial challenge, viral persistence was observed in the CNS for several weeks. CD8+ T cells required perforin to control WNV infection as adoptive transfer of WNV-primed wild-type but not perforin-deficient CD8+ T cells greatly reduced infection in the brain and spinal cord and enhanced survival of CD8-deficient mice. Analogous results were obtained when wild-type or perforin-deficient CD8+ T cells were added to congenic primary cortical neuron cultures. Taken together, our data suggest that despite the risk of immunopathogenesis, CD8+ T cells use a perforin-dependent mechanism to clear WNV from infected neurons.

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