751
|
Keller BC, Fredericksen BL, Samuel MA, Mock RE, Mason PW, Diamond MS, Gale M. Resistance to alpha/beta interferon is a determinant of West Nile virus replication fitness and virulence. J Virol 2006; 80:9424-34. [PMID: 16973548 PMCID: PMC1617238 DOI: 10.1128/jvi.00768-06] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The emergence of West Nile virus (WNV) in the Western Hemisphere is marked by the spread of pathogenic lineage I strains, which differ from typically avirulent lineage II strains. To begin to understand the virus-host interactions that may influence the phenotypic properties of divergent lineage I and II viruses, we compared the genetic, pathogenic, and alpha/beta interferon (IFN-alpha/beta)-regulatory properties of a lineage II isolate from Madagascar (MAD78) with those of a new lineage I isolate from Texas (TX02). Full genome sequence analysis revealed that MAD78 clustered, albeit distantly, with other lineage II strains, while TX02 clustered with emergent North American isolates, more specifically with other Texas strains. Compared to TX02, MAD78 replicated at low levels in cultured human cells, was highly sensitive to the antiviral actions of IFN in vitro, and demonstrated a completely avirulent phenotype in wild-type mice. In contrast to TX02 and other pathogenic forms of WNV, MAD78 was defective in its ability to disrupt IFN-induced JAK-STAT signaling, including the activation of Tyk2 and downstream phosphorylation and nuclear translocation of STAT1 and STAT2. However, replication of MAD78 was rescued in cells with a nonfunctional IFN-alpha/beta receptor (IFNAR). Consistent with this finding, the virulence of MAD78 was unmasked upon infection of mice lacking IFNAR. Thus, control of the innate host response and IFN actions is a key feature of WNV pathogenesis and replication fitness.
Collapse
Affiliation(s)
- Brian C Keller
- Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9048, USA
| | | | | | | | | | | | | |
Collapse
|
752
|
Samuel MA, Diamond MS. Pathogenesis of West Nile Virus infection: a balance between virulence, innate and adaptive immunity, and viral evasion. J Virol 2006; 80:9349-60. [PMID: 16973541 PMCID: PMC1617273 DOI: 10.1128/jvi.01122-06] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Melanie A Samuel
- Division of Infectious Diseases, Department of Molecular Microbiology, Washington University School of Medicine, Campus Box 8051, 660 S. Euclid Ave., St. Louis, MO 63110, USA
| | | |
Collapse
|
753
|
Gowen BB, Hoopes JD, Wong MH, Jung KH, Isakson KC, Alexopoulou L, Flavell RA, Sidwell RW. TLR3 Deletion Limits Mortality and Disease Severity due to Phlebovirus Infection. THE JOURNAL OF IMMUNOLOGY 2006; 177:6301-7. [PMID: 17056560 DOI: 10.4049/jimmunol.177.9.6301] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
TLR3 was the first member of the TLR family of pattern recognition receptors found to detect a conserved viral molecular pattern, dsRNA, yet supporting evidence for a major role in host defense against viral pathogens is limited. Punta Toro virus (PTV) has been shown to produce severe infection in mice, modeling disease caused by the related highly pathogenic Rift Valley fever phlebovirus in humans and domesticated ungulates. Using TLR3-deficient mice, we investigated the involvement of TLR3 in host defense against PTV infection. Compared with wild-type, TLR3(-/-) mice demonstrate increased resistance to lethal infection and have reduced liver disease associated with hepatotropic PTV infection. Infectious challenge produced comparable peak liver and serum viral loads; however, TLR3(-/-) mice were able to clear systemic virus at a slightly faster rate. Cytokine profiling suggests that TLR3 plays an important role in PTV pathogenesis through the overproduction of inflammatory mediators, which may be central to the observed differences in survival and disease severity. Compared with TLR3-deficient mice, IL-6, MCP-1, IFN-gamma, and RANTES were all present at higher levels in wild-type animals. Most dramatic was the exaggerated levels of IL-6 found systemically and in liver tissue of infected wild-type mice; however, IL-6-deficient animals were found to be more susceptible to lethal PTV infection. Taken together, we conclude that the TLR3-mediated response to PTV infection is detrimental to disease outcome and propose that IL-6, although critical to establishing antiviral defense, contributes to pathogenesis when released in excess, necessitating its controlled production as is seen with TLR3(-/-) mice.
Collapse
Affiliation(s)
- Brian B Gowen
- Institute for Antiviral Research, Department of Animal, Dairy, and Veterinary Sciences, Utah State University, 5600 Old Main, Logan, UT 84322, USA.
| | | | | | | | | | | | | | | |
Collapse
|
754
|
Nasu K, Itoh H, Yuge A, Nishida M, Narahara H. Human oviductal epithelial cells express Toll-like receptor 3 and respond to double-stranded RNA: Fallopian tube-specific mucosal immunity against viral infection. Hum Reprod 2006; 22:356-61. [PMID: 17043099 DOI: 10.1093/humrep/del385] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The aim of this study was to evaluate the site-specific immunoregulatory mechanisms against viral infection in human Fallopian tubes. METHODS We therefore investigated the effects of double-stranded RNA (dsRNA) on the production of interleukin (IL)-6, IL-8 and granulocyte chemotactic protein-2 (GCP-2) by cultured oviductal epithelial cells (OECs) using enzyme-linked immunosorbent assays. Phosphorylation of inhibitor kappaB-alpha (IkappaB-alpha) protein after dsRNA stimulation and the expression of Toll-like receptor (TLR) 3 in these cells were also evaluated by western blot analysis. RESULTS Polyriboinosinic:polyribocytidylic acid (poly I:C), a synthetic dsRNA that antagonizes TLR3, stimulated the secretion of IL-6, IL-8 and GCP-2 by OECs. Poly I:C-induced production of these cytokines by OECs was inhibited by the pretreatment of these cells with anti-TLR3 antibody. The phosphorylation of IkappaB-alpha protein was detected in OECs after stimulation by poly I:C. The expression of TLR3 was also detected in OECs. CONCLUSION These results suggest that the epithelial cells of the human Fallopian tube have evolved a unique, site-specific mechanism for recognizing viral infection. TLR3-mediated production of proinflammatory cytokines and chemokines in OECs in response to viral dsRNA may be important for antiviral immunity in the human female reproductive tract.
Collapse
Affiliation(s)
- K Nasu
- Department of Obstetrics and Gynecology, Faculty of Medicine, Oita University, Oita, Japan.
| | | | | | | | | |
Collapse
|
755
|
Honda K, Taniguchi T. IRFs: master regulators of signalling by Toll-like receptors and cytosolic pattern-recognition receptors. Nat Rev Immunol 2006; 6:644-58. [PMID: 16932750 DOI: 10.1038/nri1900] [Citation(s) in RCA: 1250] [Impact Index Per Article: 69.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The interferon-regulatory factor (IRF) family of transcription factors was initially found to be involved in the induction of genes that encode type I interferons. IRFs have now been shown to have functionally diverse roles in the regulation of the immune system. Recently, the crucial involvement of IRFs in innate and adaptive immune responses has been gaining much attention, particularly with the discovery of their role in immunoregulation by Toll-like receptors and other pattern-recognition receptors.
Collapse
Affiliation(s)
- Kenya Honda
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
| | | |
Collapse
|
756
|
Debiasi RL, Tyler KL. West Nile virus meningoencephalitis. ACTA ACUST UNITED AC 2006; 2:264-75. [PMID: 16932563 PMCID: PMC3773989 DOI: 10.1038/ncpneuro0176] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 03/07/2006] [Indexed: 01/10/2023]
Abstract
Since its first appearance in the US in 1999, West Nile virus (WNV) has emerged as the most common cause of epidemic meningoencephalitis in North America. In the 6 years following the 1999 outbreak, the geographic range and burden of the disease in birds, mosquitoes and humans has greatly expanded to include the 48 contiguous US and 7 Canadian provinces, as well as Mexico, the Caribbean islands and Colombia. WNV has shown an increasing propensity for neuroinvasive disease over the past decade, with varied presentations including meningitis, encephalitis and acute flaccid paralysis. Although neuroinvasive disease occurs in less than 1% of infected individuals, it is associated with high mortality. From 1999-2005, more than 8,000 cases of neuroinvasive WNV disease were reported in the US, resulting in over 780 deaths. In this review, we discuss epidemiology, risk factors, clinical features, diagnosis and prognosis of WNV meningoencephalitis, along with potential treatments.
Collapse
Affiliation(s)
- Roberta L Debiasi
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, USA
| | | |
Collapse
|
757
|
Pawar RD, Patole PS, Wörnle M, Anders HJ. Microbial nucleic acids pay a Toll in kidney disease. Am J Physiol Renal Physiol 2006; 291:F509-16. [PMID: 16597607 DOI: 10.1152/ajprenal.00453.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Nucleic acids provide more than the genetic code that determines the morphological and functional phenotype of microbes and eukaryotes. In fact, nucleic acids have immunomodulatory functions as they are recognized by a set of pattern-recognition receptors that initiate and modulate immune responses in the host. Toll-like receptor (TLR)-3 recognizes double-stranded RNA, TLR7 and TLR8 recognize single-stranded RNA, CpG-DNA is a ligand for TLR9, and all of these TLRs are expressed in the nephritic kidney. In this review, we summarize recent advances in this field and discuss new hypotheses for the pathogenesis of kidney diseases that are triggered by infectious organisms.
Collapse
Affiliation(s)
- Rahul D Pawar
- Nephrological Center, Medical Policlinic, University of Munich, Munich, Germany
| | | | | | | |
Collapse
|
758
|
Abstract
AbstractThe innate immune system provides the first line of host defense against invading microorganisms before the development of adaptive immune responses. Innate immune responses are initiated by germline-encoded pattern recognition receptors (PRRs), which recognize specific structures of microorganisms. Toll-like receptors (TLRs) are pattern-recognition receptors that sense a wide range of microorganisms, including bacteria, fungi, protozoa and viruses. TLRs exist either on the cell surface or in the lysosome/endosome compartment and induce innate immune responses. Recently, cytoplasmic PRRs have been identified which detect pathogens that have invaded the cytosol. This review focuses on the pathogen recognition of PRRs in innate immunity.
Collapse
|
759
|
Honda K, Takaoka A, Taniguchi T. Type I Inteferon Gene Induction by the Interferon Regulatory Factor Family of Transcription Factors. Immunity 2006; 25:349-60. [PMID: 16979567 DOI: 10.1016/j.immuni.2006.08.009] [Citation(s) in RCA: 1044] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Induction of type I interferons (IFNs) by viruses and other pathogens is crucial for innate immunity, and it is mediated by the activation of pattern-recognition receptors, such as Toll-like receptors and cytosolic receptors such as RIG-I and MDA5. The type I IFN induction is primarily controlled at the gene transcriptional level, wherein a family of transcription factors, interferon regulatory factors (IRFs), plays central roles. Here, we summarize the recent studies on IRFs, providing a paradigm of how genes are ingeniously regulated during immune responses. We also consider some evolutional aspects on the IFN-IRF system.
Collapse
Affiliation(s)
- Kenya Honda
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | | | | |
Collapse
|
760
|
Samuel MA, Whitby K, Keller BC, Marri A, Barchet W, Williams BRG, Silverman RH, Gale M, Diamond MS. PKR and RNase L contribute to protection against lethal West Nile Virus infection by controlling early viral spread in the periphery and replication in neurons. J Virol 2006; 80:7009-19. [PMID: 16809306 PMCID: PMC1489062 DOI: 10.1128/jvi.00489-06] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
West Nile virus (WNV) is a neurotropic, mosquito-borne flavivirus that can cause lethal meningoencephalitis. Type I interferon (IFN) plays a critical role in controlling WNV replication, spread, and tropism. In this study, we begin to examine the effector mechanisms by which type I IFN inhibits WNV infection. Mice lacking both the interferon-induced, double-stranded-RNA-activated protein kinase (PKR) and the endoribonuclease of the 2',5'-oligoadenylate synthetase-RNase L system (PKR(-/-) x RL(-/-)) were highly susceptible to subcutaneous WNV infection, with a 90% mortality rate compared to the 30% mortality rate observed in congenic wild-type mice. PKR(-/-) x RL(-/-) mice had increased viral loads in their draining lymph nodes, sera, and spleens, which led to early viral entry into the central nervous system (CNS) and higher viral burden in neuronal tissues. Although mice lacking RNase L showed a higher CNS viral burden and an increased mortality, they were less susceptible than the PKR(-/-) x RL(-/-) mice; thus, we also infer an antiviral role for PKR in the control of WNV infection. Notably, a deficiency in both PKR and RNase L resulted in a decreased ability of type I IFN to inhibit WNV in primary macrophages and cortical neurons. In contrast, the peripheral neurons of the superior cervical ganglia of PKR(-/-) x RL(-/-) mice showed no deficiency in the IFN-mediated inhibition of WNV. Our data suggest that PKR and RNase L contribute to IFN-mediated protection in a cell-restricted manner and control WNV infection in peripheral tissues and some neuronal subtypes.
Collapse
Affiliation(s)
- Melanie A Samuel
- Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
761
|
Hardarson HS, Baker JS, Yang Z, Purevjav E, Huang CH, Alexopoulou L, Li N, Flavell RA, Bowles NE, Vallejo JG. Toll-like receptor 3 is an essential component of the innate stress response in virus-induced cardiac injury. Am J Physiol Heart Circ Physiol 2006; 292:H251-8. [PMID: 16936008 DOI: 10.1152/ajpheart.00398.2006] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Enterovirus-induced myocardial injury can lead to severe heart failure. To date, little is known about the early innate stress response that contributes to host defense in the heart. Toll-like receptor 3 (TLR3) is important in the initiation of the innate antiviral response. We investigated the involvement of TLR3, which recognizes viral double-stranded RNA, on encephalomyocarditis virus (EMCV) infection. To examine the contribution of TLR3 in protection from EMCV infection, we infected mice deficient in TLR3 with 50 plaque-forming units of EMCV. TLR3-deficient (TLR3(-/-)) mice were more susceptible to EMCV infection and had a significantly higher viral load in the heart compared with TLR3(+/+) mice. Histopathological examination showed that the inflammatory changes of the myocardium were less marked in TLR3(-/-) than in TLR3(+/+)mice. TLR3(-/-) mice had impaired proinflammatory cytokine and chemokine expression in the heart following EMCV infection. However, the expression of interferon-beta was not impaired in EMCV-infected TLR3(-/-) mice. EMCV infection leads to a TLR3-dependent innate stress response, which is involved in mediating protection against virus-induced myocardial injury.
Collapse
Affiliation(s)
- Hordur S Hardarson
- Department of Pediatrics, Section of Infectious Diseases, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas 77030, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
762
|
Hunsperger EA, Roehrig JT. Temporal analyses of the neuropathogenesis of a West Nile virus infection in mice. J Neurovirol 2006; 12:129-39. [PMID: 16798674 DOI: 10.1080/13550280600758341] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A West Nile virus (WNV) infection in humans can produce neurological symptoms including acute flaccid paralysis, encephalitis, meningitis and myelitis. To investigate the pathogenesis of WNV in the peripheral and the central nervous system (PNS and CNS), the authors used a murine footpad inoculation model of WNV infection. Survival curves of virus-infected animals of ages 4- to 6-weeks-old demonstrated age-dependent mortality where older animals (6-weeks-old) had a higher mortality rate compared to younger animals (4- and 5-weeks-old). The mice that survived the virus infection formed WNV-reactive antibodies, confirming viral infection and clearance. The localization of viral RNA (vRNA) and antigen in infected murine tissues was investigated using TaqMan and immunohistochemistry (IHC) respectively. During a nine day infection, vRNA levels in the spinal cord and brainstem fluctuated, suggesting early viral clearance from these tissues by days 3-4 p.i. with later re-introduction. Viral antigens detected using IHC were primarily observed in three main regions of the brain: cortex, hippocampus and brainstem. Additionally, the dorsal root ganglion neurons of the PNS stained positive for viral antigens. These data are consistent with multiple routes of neuroinvasion following a peripheral inoculation of virus and do not preclude the previous observation that virus-infected peripheral neurons can introduce virus into the CNS by a retrograde transport mechanism.
Collapse
Affiliation(s)
- Elizabeth A Hunsperger
- Division of Vector-Borne Infectious Disease, Centers for Disease Control and Prevention/National Center for Infectious Diseases, Ft. Collins, Colorado, USA.
| | | |
Collapse
|
763
|
Oh W, Yang MR, Lee EW, Park KM, Pyo S, Yang JS, Lee HW, Song J. Jab1 mediates cytoplasmic localization and degradation of West Nile virus capsid protein. J Biol Chem 2006; 281:30166-74. [PMID: 16882664 DOI: 10.1074/jbc.m602651200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The clinical manifestations of West Nile virus (WNV), a member of the Flavivirus family, include febrile illness, sporadic encephalitis, and paralysis. The capsid (Cp) of WNV is thought to participate in these processes by inducing apoptosis through mitochondrial dysfunction and activation of caspase-9 and caspase-3. To further identify the molecular mechanism of the WNV capsid protein (WNVCp), yeast two-hybrid assays were employed using WNV-Cp as bait. Jab1, the fifth subunit of the COP9 signalosome, was subsequently identified as a molecule that interacts with WNVCp. Immunoprecipitation and glutathione S-transferase pulldown assays confirmed that direct interaction could occur between WNVCp and Jab1. Immunofluorescence microscopy demonstrated that the overexpressed WNVCp, which localized to the nucleolus, was translocated to the cytoplasm upon its co-expression with Jab1. When treated with leptomycin B, Jab1-facilitated nuclear exclusion of WNVCp was prevented, which indicated that the CRM1 complex is required for Jab1-facilitated nuclear export of WNVCp. Moreover, Jab1 promoted the degradation of WNVCp in a proteasome-dependent way. Consistent with this, WNVCp-mediated cell cycle arrest at the G(2) phase in H1299 was prevented by exogenous Jab1. Finally, an analysis of WNVCp deletion mutants indicated that the first 15 amino acids were required for interaction with Jab1. Furthermore, the double-point mutant of the WNVCp, P5A/P8A, was incapable of binding to Jab1. These results indicate that Jab1 has a potential protective effect against pathogenic WNVCp and might provide a novel target site for the treatment of disease caused by WNV.
Collapse
Affiliation(s)
- Wonkyung Oh
- Department of Food Science and Biotechnology, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | | | | | | | | | | | | | | |
Collapse
|
764
|
Abstract
Since its entry into North America in 1999, West Nile virus has spread throughout the USA and Canada, and now annually causes a clinical spectrum of human disease ranging from a self-limiting acute febrile illness to potentially lethal encephalitis. Although no therapy is currently approved for use in humans, several strategies are being pursued to develop effective prophylaxis and treatments. This review describes the epidemiology, clinical presentation and pathogenesis of West Nile virus infection, and highlights recent progress towards an effective therapy.
Collapse
Affiliation(s)
- Michael S Diamond
- Department of Medicine, Washington University School of Medicine, Box 8051, St Louis, MO 63110, USA.
| |
Collapse
|
765
|
Schneider BS, Soong L, Girard YA, Campbell G, Mason P, Higgs S. Potentiation of West Nile encephalitis by mosquito feeding. Viral Immunol 2006; 19:74-82. [PMID: 16553552 DOI: 10.1089/vim.2006.19.74] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mosquitoes infect human beings with arboviruses while taking a blood meal, inoculating virus with their saliva. Mosquito saliva contains compounds that counter host hemostatic, inflammatory, and immune responses. Modulation of these crucial defensive responses may facilitate virus infection. Using a murine model we explored the potential for mosquitoes to impact the course of West Nile virus (WNV) disease by determining whether differences in pathogenesis occurred in the presence or absence of mosquito saliva. Mice inoculated intradermally with 10(4) pfu of WNV subsequent to the feeding of mosquitoes developed more progressive infection, higher viremia, and accelerated neuroinvasion than the mice inoculated with WNV alone. At a lower dose of WNV (10(2) pfu), mice fed upon by mosquitoes had a lower survival rate. This study suggests that mosquito feeding and factors in mosquito saliva can potentiate WNV infection, and offers a possible mechanism for this effect via accelerated infection of the brain.
Collapse
Affiliation(s)
- Bradley S Schneider
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
| | | | | | | | | | | |
Collapse
|
766
|
Phares TW, Kean RB, Mikheeva T, Hooper DC. Regional differences in blood-brain barrier permeability changes and inflammation in the apathogenic clearance of virus from the central nervous system. THE JOURNAL OF IMMUNOLOGY 2006; 176:7666-75. [PMID: 16751414 DOI: 10.4049/jimmunol.176.12.7666] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The loss of blood-brain barrier (BBB) integrity in CNS inflammatory responses triggered by infection and autoimmunity has generally been associated with the development of neurological signs. In the present study, we demonstrate that the clearance of the attenuated rabies virus CVS-F3 from the CNS is an exception; increased BBB permeability and CNS inflammation occurs in the absence of neurological sequelae. We speculate that regionalization of the CNS inflammatory response contributes to its lack of pathogenicity. Despite virus replication and the expression of several chemokines and IL-6 in both regions being similar, the up-regulation of MIP-1beta, TNF-alpha, IFN-gamma, and ICAM-1 and the loss of BBB integrity was more extensive in the cerebellum than in the cerebral cortex. The accumulation of CD4- and CD19-positive cells was higher in the cerebellum than the cerebral cortex. Elevated CD19 levels were paralleled by kappa-L chain expression levels. The timing of BBB permeability changes, kappa-L chain expression in CNS tissues, and Ab production in the periphery suggest that the in situ production of virus-neutralizing Ab may be more important in virus clearance than the infiltration of circulating Ab. The data indicate that, with the possible exception of CD8 T cells, the effectors of rabies virus clearance are more commonly targeted to the cerebellum. This is likely the result of differences in the capacity of the tissues of the cerebellum and cerebral cortex to mediate the events required for BBB permeability changes and cell invasion during virus infection.
Collapse
Affiliation(s)
- Timothy W Phares
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | | | | |
Collapse
|
767
|
Abstract
Viral infections are first detected by a set of innate immunity receptors that detect primary infections by pathogens, and trigger a transcriptional response. Among the induced target genes, type I interferons (IFNs) are central to the antiviral response of the host. The receptors and signaling pathways that mediate the strong induction of the synthesis of these cytokines have long remained elusive. In the past few years, Toll-like receptors (TLRs) emerged as important sensors of infections. Several TLRs participate in the recognition of virus infection, interacting in particular with viral nucleic acids. Upon activation, TLRs interact with different cytosolic adapter molecules and activate transcription factors of the nuclear factor-kappaB and IFN regulatory factor families that concur to mediate induction of IFN-alpha/beta and other inflammatory cytokines. In addition to the transmembrane TLRs, cytosolic helicases also detect viral nucleic acids, and trigger type I IFN synthesis.
Collapse
Affiliation(s)
- D Galiana-Arnoux
- UPR9022 CNRS, Institut de Biologie Moléculaire et Cellulaire, 15, rue René Descartes, Strasbourg, France
| | | |
Collapse
|
768
|
Best SM, Mitzel DN, Bloom ME. Action and reaction: the arthropod-borne flaviviruses and host interferon responses. Future Virol 2006. [DOI: 10.2217/17460794.1.4.447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The arthropod-borne flaviviruses include tick- and mosquito-borne viruses that are causes of globally significant emerging diseases. These single-stranded RNA viruses are exquisitely sensitive to the antiviral effects of host interferons. However, both the tick- and mosquito-borne flaviviruses are capable of modulating the interferon response. Despite the high degree of similarity among members of the flavivirus genus, the mechanisms employed by individual viruses to modulate interferon responses differ. This review considers the arthropod-borne flaviviruses and the host interferon response as a pair of forces, the action and the reaction. The interaction of these two forces has led to a complex relationship between virus and host. An increased understanding of these interactions will likely facilitate the rational design of novel vaccines and therapeutics.
Collapse
Affiliation(s)
- Sonja M Best
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, NIAID, NIH, 903 South Fourth Street, Hamilton, MT 59840, USA
| | - Dana N Mitzel
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, NIAID, NIH, 903 South Fourth Street, Hamilton, MT 59840, USA
| | - Marshall E Bloom
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, NIAID, NIH, 903 South Fourth Street, Hamilton, MT 59840, USA
| |
Collapse
|
769
|
Lim JK, Glass WG, McDermott DH, Murphy PM. CCR5: no longer a ‘good for nothing’ gene – chemokine control of West Nile virus infection. Trends Immunol 2006; 27:308-12. [PMID: 16753343 DOI: 10.1016/j.it.2006.05.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 04/25/2006] [Accepted: 05/16/2006] [Indexed: 10/24/2022]
Abstract
The chemokine receptor CCR5 was identified in 1996 as a crucial host factor exploited by HIV for cell entry. CCR5 presumably functions normally in antimicrobial host defense because it generally mediates leukocyte chemotactic responses; however, evidence of antimicrobial functions for CCR5 in humans has been elusive. Recently, genetic analyses in mice and humans have provided strong evidence for the CCR5 control of infection by West Nile virus (WNV), a re-emerging pathogen capable of causing fatal encephalitis. Thus, the same receptor can benefit or harm the host, depending on the virus. Although CCR5 might be a logical target for new drug development in HIV/AIDS, the benefits of blocking CCR5 could carry the cost of an increased risk of WNV disease in co-infected patients.
Collapse
Affiliation(s)
- Jean K Lim
- Molecular Signaling Section, Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | |
Collapse
|
770
|
Xu J, Yang Y, Sun J, Ding Y, Su L, Shao C, Jiang B. Expression of Toll-like receptors and their association with cytokine responses in peripheral blood mononuclear cells of children with acute rotavirus diarrhoea. Clin Exp Immunol 2006; 144:376-81. [PMID: 16734605 PMCID: PMC1941968 DOI: 10.1111/j.1365-2249.2006.03079.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
To understand virus and host interactions and host responses to rotavirus infection in children, we analysed by real-time polymerase chain reaction (PCR) the expression of mRNA for five Toll-like receptors (TLRs) (TLR2, TLR3, TLR4, TLR7 and TLR8) and four T helper (Th)1 and Th2 cytokines [interleukin (IL)-2, IL-12, interferon (IFN)-gamma and IL-4) in peripheral blood mononuclear cells (PBMC) of children with acute rotavirus diarrhoea. We observed significantly higher expression of genes encoding TLR2, TLR3, TLR4, TLR7 and TLR8 in PBMC of 41% (31/75) patients within 3 days of illness onset than those in healthy children. After 3 days of illness onset, only TLR3 and TLR8 mRNA expressions were still significantly (P<0.05) increased in 59% (44/75) children with diarrhoea. We also observed significantly (P<0.05) elevated expression of IL-12p40 and IFN-gamma in PBMC of patients during the entire period of illness and the first 3 days of illness, respectively. We further demonstrated a weak but significant association between elevated levels of gene expression of four TLRs (TLR2, TLR3, TLR4 and TLR8) and IFN-gamma. Our results suggest that multiple TLRs may modulate the immune response in the acute phase of rotavirus infection and play a role in the activation of IFN-gamma.
Collapse
Affiliation(s)
- J Xu
- Pediatric Institute, Children's Hospital, Department of Pediatrics, Fudan University, Shanghai, China.
| | | | | | | | | | | | | |
Collapse
|
771
|
Yang X, Murthy V, Schultz K, Tatro JB, Fitzgerald KA, Beasley D. Toll-like receptor 3 signaling evokes a proinflammatory and proliferative phenotype in human vascular smooth muscle cells. Am J Physiol Heart Circ Physiol 2006; 291:H2334-43. [PMID: 16782847 DOI: 10.1152/ajpheart.00252.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Inflammation plays a key role in atherogenesis, perhaps promoted by bacterial and viral products present within the artery wall. Vascular smooth muscle cells (VSMC) can express certain bacterially responsive Toll-like receptors (TLR), which promote a proinflammatory and proliferative VSMC phenotype when activated, but it is unknown whether virally activated TLR can regulate VSMC phenotype. Here we tested the role in VSMC of TLR3, which is activated by double-stranded (dsRNA), a molecular signature of viruses. VSMC from multiple vessel types, including human coronary artery (HCoASMC) and mouse aorta (MAoSMC), expressed TLR3 constitutively, and HCoASMC were exquisitely sensitive to dsRNA-stimulated release of monocyte chemoattractant protein-1 (MCP-1) and interleukin-6. dsRNA-induced MCP-1 release was abolished by small interfering RNA-mediated TLR3 knockdown in HCoASMC and was absent in TLR3-/- MAoSMC but was unimpaired in TLR2-/- and in TLR4 signaling-deficient MAoSMC. Exposure to dsRNA also activated ERK1/2 and NF-kappaB in both human and murine SMC, but these effects were absent in SMC from TLR3-deficient mice, demonstrating a crucial role of TLR3 signaling. dsRNA also stimulated proliferation of HCoASMC, indicated by increased DNA synthesis, and induced persistent elevations in the intracellular levels of growth-promoting mediators, including interleukin-1alpha and phospho-ERK1/2. We conclude that exposure of HCoASMC to dsRNA elicits dramatic TLR3-mediated proinflammatory and proproliferative phenotypic changes, responses that could potentially be triggered by viral infection of cells within the arterial wall.
Collapse
Affiliation(s)
- Xin Yang
- Tufts-New England Medical Center, Box 8486, 750 Washington St., Boston, MA 02111, USA
| | | | | | | | | | | |
Collapse
|
772
|
Goffic RL, Balloy V, Lagranderie M, Alexopoulou L, Escriou N, Flavell R, Chignard M, Si-Tahar M. Detrimental contribution of the Toll-like receptor (TLR)3 to influenza A virus-induced acute pneumonia. PLoS Pathog 2006; 2:e53. [PMID: 16789835 PMCID: PMC1475659 DOI: 10.1371/journal.ppat.0020053] [Citation(s) in RCA: 405] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 04/26/2006] [Indexed: 12/16/2022] Open
Abstract
Influenza A virus (IAV) is the etiological agent of a highly contagious acute respiratory disease that causes epidemics and considerable mortality annually. Recently, we demonstrated, using an in vitro approach, that the pattern recognition Toll-like receptor (TLR)3 plays a key role in the immune response of lung epithelial cells to IAV. In view of these data and the fact that the functional role of TLR3 in vivo is still debated, we designed an investigation to better understand the role of TLR3 in the mechanisms of IAV pathogenesis and host immune response using an experimental murine model. The time-course of several dynamic parameters, including animal survival, respiratory suffering, viral clearance, leukocyte recruitment into the airspaces and secretion of critical inflammatory mediators, was compared in infected wild-type and TLR3−/− mice. First, we found that the pulmonary expression of TLR3 is constitutive and markedly upregulated following influenza infection in control mice. Notably, when compared to wild-type mice, infected TLR3−/− animals displayed significantly reduced inflammatory mediators, including RANTES (regulated upon activation, normal T cell expressed and secreted), interleukin-6, and interleukin-12p40/p70 as well as a lower number of CD8+ T lymphocytes in the bronchoalveolar airspace. More important, despite a higher viral production in the lungs, mice deficient in TLR3 had an unexpected survival advantage. Hence, to our knowledge, our findings show for the first time that TLR3-IAV interaction critically contributes to the debilitating effects of a detrimental host inflammatory response. Influenza A virus (IAV) is responsible for highly contagious acute respiratory disease. Recent concerns have risen concerning a possible influenza pandemic in the near future. Thus, a better understanding of the molecular mechanisms of IAV pathogenesis and host immune responses is required for the development of more efficient means of prevention and treatment of influenza. The Toll-like receptor (TLR)3 is a member of a family of receptors that detects microbes and triggers host defenses. We previously demonstrated using an in vitro approach, that the TLR3 plays a key role in the response of lung epithelial cells to IAV. Here, we used a mouse model to dissect the in vivo importance of TLR3-dependent responses during influenza. The time-course of several parameters, including animal survival, respiratory distress, viral clearance, and inflammation, was compared in infected control wild-type and TLR3-deficient mice. Our findings reveal that TLR3−/− mice have an unexpected advantage against IAV challenge as we show for the first time that a reduction of TLR3-mediated inflammatory response reduces the clinical manifestations of IAV-induced pneumonia.
Collapse
Affiliation(s)
- Ronan Le Goffic
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- INSERM, E336, Paris, France
| | - Viviane Balloy
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- INSERM, E336, Paris, France
| | | | - Lena Alexopoulou
- Université de la Méditerranée, Faculté des Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy (CIML), Marseille, France
- INSERM U631, Marseille, France
- CNRS, UMR6102, Marseille, France
| | - Nicolas Escriou
- Institut Pasteur, Unité de Génétique Moléculaire des Virus Respiratoires, CNRS URA 1966, Paris, France
| | - Richard Flavell
- Section of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Howard Hughes Medical Institute, New Haven, Connecticut, United States of America
| | - Michel Chignard
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- INSERM, E336, Paris, France
| | - Mustapha Si-Tahar
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- INSERM, E336, Paris, France
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
773
|
Meylan E, Tschopp J. Toll-like receptors and RNA helicases: two parallel ways to trigger antiviral responses. Mol Cell 2006; 22:561-9. [PMID: 16762830 DOI: 10.1016/j.molcel.2006.05.012] [Citation(s) in RCA: 296] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The early detection by the host of invading microorganisms, including viruses, depends on a limited number of specific receptors that recognize pathogen-associated molecular patterns (PAMPs). A few of these PAMPs, including ssRNA and dsRNA, are recognized by Toll-like receptors (TLR)-7/8 and TLR3, respectively. Activation of an antiviral TLR-dependent signaling cascade leads to the activation of the key transcription factors IRF and NF-kappaB, which promote antiviral responses through induction of specific genes. Recently, a second system has been described, which relies on the cytoplasmic recognition of dsRNA by RNA helicases such as RIG-I. In this review, we discuss the mechanistic aspects of these important arms of the host innate response to dsRNA and a few viral strategies utilized to counteract them.
Collapse
Affiliation(s)
- Etienne Meylan
- Department of Biochemistry, University of Lausanne, BIL Biomedical Research Center, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | | |
Collapse
|
774
|
Shrestha B, Wang T, Samuel MA, Whitby K, Craft J, Fikrig E, Diamond MS. Gamma interferon plays a crucial early antiviral role in protection against West Nile virus infection. J Virol 2006; 80:5338-48. [PMID: 16699014 PMCID: PMC1472130 DOI: 10.1128/jvi.00274-06] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 03/08/2006] [Indexed: 12/17/2022] Open
Abstract
West Nile virus (WNV) causes a severe central nervous system (CNS) infection in humans, primarily in the elderly and immunocompromised. Prior studies have established an essential protective role of several innate immune response elements, including alpha/beta interferon (IFN-alpha/beta), immunoglobulin M, gammadelta T cells, and complement against WNV infection. In this study, we demonstrate that a lack of IFN-gamma production or signaling results in increased vulnerability to lethal WNV infection by a subcutaneous route in mice, with a rise in mortality from 30% (wild-type mice) to 90% (IFN-gamma(-/-) or IFN-gammaR(-/-) mice) and a decrease in the average survival time. This survival pattern in IFN-gamma(-/-) and IFN-gammaR(-/-) mice correlated with higher viremia and greater viral replication in lymphoid tissues. The increase in peripheral infection led to early CNS seeding since infectious WNV was detected several days earlier in the brains and spinal cords of IFN-gamma(-/-) or IFN-gammaR(-/-) mice. Bone marrow reconstitution experiments showed that gammadelta T cells require IFN-gamma to limit dissemination by WNV. Moreover, treatment of primary dendritic cells with IFN-gamma reduced WNV production by 130-fold. Collectively, our experiments suggest that the dominant protective role of IFN-gamma against WNV is antiviral in nature, occurs in peripheral lymphoid tissues, and prevents viral dissemination to the CNS.
Collapse
Affiliation(s)
- Bimmi Shrestha
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., Box 8051, St. Louis, MO 63110, USA
| | | | | | | | | | | | | |
Collapse
|
775
|
Abstract
Toll-like receptors (TLRs) are a family of pattern-recognition receptors expressed on cells of the innate immune system that allow for the recognition of conserved structural motifs on a wide array of pathogens, referred to as pathogen-associated molecular patterns, as well as some endogenous molecules. The recent emergence of studies examining TLRs in the central nervous system (CNS) indicates that these receptors not only play a role in innate immunity in response to infectious diseases but may also participate in CNS autoimmunity, neurodegeneration, and tissue injury. This review summarizes the experimental evidence demonstrating a role for TLRs in the context of CNS inflammation in both infectious and noninfectious conditions.
Collapse
Affiliation(s)
- Tammy Kielian
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
| |
Collapse
|
776
|
Gitlin L, Barchet W, Gilfillan S, Cella M, Beutler B, Flavell RA, Diamond MS, Colonna M. Essential role of mda-5 in type I IFN responses to polyriboinosinic:polyribocytidylic acid and encephalomyocarditis picornavirus. Proc Natl Acad Sci U S A 2006; 103:8459-64. [PMID: 16714379 PMCID: PMC1464000 DOI: 10.1073/pnas.0603082103] [Citation(s) in RCA: 865] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The innate immune system recognizes viral dsRNA through two distinct pathways; the Toll-like receptor 3 (TLR3) pathway detects dsRNA phagocytosed in endosomes; the helicases retinoic acid-induced protein I (RIG-I) and melanoma differentiation-associated gene-5 (mda-5) detect cytoplasmic dsRNA generated during viral replication. Both RIG-I and mda-5 can bind polyriboinosinic:polyribocytidylic acid (polyI:C), the synthetic analog of viral dsRNA, and mediate type I IFN responses to polyI:C and multiple RNA viruses in vitro. We generated mda-5-deficient mice and showed that mda-5 is the dominant receptor mediating type I IFN secretion in response to polyI:C in vitro and in vivo. Moreover, mda-5-/- mice exhibited a selectively impaired antiviral response to encephalomyocarditis picornavirus, indicating functional specialization of mda-5 in vivo.
Collapse
Affiliation(s)
- Leonid Gitlin
- *Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, MO 63110
| | - Winfried Barchet
- *Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, MO 63110
| | - Susan Gilfillan
- *Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, MO 63110
| | - Marina Cella
- *Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, MO 63110
| | - Bruce Beutler
- Department of Immunology, Scripps Research Institute, La Jolla, CA 92037; and
| | - Richard A. Flavell
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520
| | | | - Marco Colonna
- *Department of Pathology and Immunology, Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, MO 63110
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
777
|
McKimmie CS, Roy D, Forster T, Fazakerley JK. Innate immune response gene expression profiles of N9 microglia are pathogen-type specific. J Neuroimmunol 2006; 175:128-41. [PMID: 16697053 DOI: 10.1016/j.jneuroim.2006.03.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 03/15/2006] [Accepted: 03/20/2006] [Indexed: 12/25/2022]
Abstract
Glial cells, particularly microglia, are thought to play a pivotal role in initiating and guiding innate immune responses to CNS infections and in perpetuating inflammation and pathology in CNS diseases such as multiple sclerosis and Alzheimer's disease. We describe here the development and use of a new microarray designed to specifically profile transcript expression of innate immunity genes. Microarray analysis validated by quantitative PCR demonstrated an extensive range of pattern recognition receptor gene expression in resting N9 microglia, including Toll-like receptors, scavenger receptors and lectins. Stimulation with LPS or infection with virus modulated pattern recognition receptor, cytokine, chemokine and other innate immune transcripts in a distinct and stimulus-specific manner. This study demonstrates that a single glial cell phenotype has an innate capability to detect infection, determine its form and generate specific responses.
Collapse
Affiliation(s)
- Clive S McKimmie
- Virology, Centre for Infectious Diseases College of Medicine and Veterinary Medicine, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | | | | | | |
Collapse
|
778
|
Pijlman GP, Suhrbier A, Khromykh AA. Kunjin virus replicons: an RNA-based, non-cytopathic viral vector system for protein production, vaccine and gene therapy applications. Expert Opin Biol Ther 2006; 6:135-45. [PMID: 16436039 DOI: 10.1517/14712598.6.2.135] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The application of viral vectors for gene expression and delivery is rapidly evolving, with several entering clinical trials. However, a number of issues, including safety, gene expression levels, cell selectivity and antivector immunity, are driving the search for new vector systems. A number of replicon-based vectors derived from positive-strand RNA viruses have recently been developed, and this paper reviews the current knowledge on the first flavivirus replicon system, which is based on the Australian flavivirus Kunjin (KUN). Like most replicon systems, KUN replicons can be delivered as DNA, RNA or virus-like particles, they replicate their RNA in the cytoplasm and direct prolonged high-level gene expression. However, unlike most alphavirus replicon systems, KUN replicons are non-cytopathic, with transfected cells able to divide, allowing the establishment of cell lines stably expressing replicon RNA and heterologous genes. As vaccine vectors KUN replicons can induce potent, long-lived, protective, immunogen-specific CD8+ T cell immunity, a feature potentially related to extended production of antigen and double-stranded RNA-induced 'danger signals'. The identification of KUN replicon mutants that induce increased levels of IFN-alpha/beta has also spawned investigation of KUN replicons for use in cancer gene therapy. The unique characteristics of KUN replicons may thus make them suitable for specific protein production, vaccine and gene therapy applications.
Collapse
Affiliation(s)
- Gorben P Pijlman
- University of Queensland, School of Molecular and Microbial Sciences, MBS Bld 76, St. Lucia, 4072 QLD, Australia
| | | | | |
Collapse
|
779
|
Glass WG, Lim JK, Cholera R, Pletnev AG, Gao JL, Murphy PM. Chemokine receptor CCR5 promotes leukocyte trafficking to the brain and survival in West Nile virus infection. ACTA ACUST UNITED AC 2006; 202:1087-98. [PMID: 16230476 PMCID: PMC2213214 DOI: 10.1084/jem.20042530] [Citation(s) in RCA: 289] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The molecular immunopathogenesis of West Nile virus (WNV) infection is poorly understood. Here, we characterize a mouse model for WNV using a subcutaneous route of infection and delineate leukocyte subsets and immunoregulatory factors present in the brains of infected mice. Central nervous system (CNS) expression of the chemokine receptor CCR5 and its ligand CCL5 was prominently up-regulated by WNV, and this was associated with CNS infiltration of CD4+ and CD8+ T cells, NK1.1+ cells and macrophages expressing the receptor. The significance of CCR5 in pathogenesis was established by mortality studies in which infection of CCR5-/- mice was rapidly and uniformly fatal. In the brain, WNV-infected CCR5-/- mice had increased viral burden but markedly reduced NK1.1+ cells, macrophages, and CD4+ and CD8+ T cells compared with WNV-infected CCR5+/+ mice. Adoptive transfer of splenocytes from WNV-infected CCR5+/+ mice into infected CCR5-/- mice increased leukocyte accumulation in the CNS compared with transfer of splenocytes from infected CCR5-/- mice into infected CCR5-/- mice, and increased survival to 60%, the same as in infected CCR5+/+ control mice. We conclude that CCR5 is a critical antiviral and survival determinant in WNV infection of mice that acts by regulating trafficking of leukocytes to the infected brain.
Collapse
Affiliation(s)
- William G Glass
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
780
|
Barrat FJ, Meeker T, Gregorio J, Chan JH, Uematsu S, Akira S, Chang B, Duramad O, Coffman RL. Nucleic acids of mammalian origin can act as endogenous ligands for Toll-like receptors and may promote systemic lupus erythematosus. ACTA ACUST UNITED AC 2006; 202:1131-9. [PMID: 16230478 PMCID: PMC2213213 DOI: 10.1084/jem.20050914] [Citation(s) in RCA: 695] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Raised serum levels of interferon (IFN)-alpha have been observed in systemic lupus erythematosus (SLE) patients, and these levels are correlated with both disease activity and severity. The origin of this IFN-alpha is still unclear, but increasing evidence suggests the critical involvement of activated plasmacytoid predendritic cells (PDCs). In SLE patients, DNA and RNA viruses, as well as immune complexes (ICs), that consist of autoantibodies specific to self-DNA and RNA protein particles can stimulate production of IFN-alpha. We have developed three series of oligonucleotide (ODN)-based inhibitors of Toll-like receptor (TLR) signaling. These ODNs include inhibitors of TLR9, inhibitors of TLR7 but not TLR9, and sequences that inhibit both TLR7 and TLR9. Specificity of these inhibitors is confirmed by inhibition of IFN-alpha production by PDCs in response to DNA or RNA viruses. We show that mammalian DNA and RNA, in the form of ICs, are potent self-antigens for TLR9 and TLR7, respectively, and induce IFN-alpha production by PDCs. This work suggests that TLRs may have a critical role in the promotion of lupus through the induction of IFN-alpha by PDCs. These inhibitors of TLR signaling thus represent novel therapeutic agents with potential for the treatment of lupus.
Collapse
|
781
|
Mehlhop E, Diamond MS. Protective immune responses against West Nile virus are primed by distinct complement activation pathways. ACTA ACUST UNITED AC 2006; 203:1371-81. [PMID: 16651386 PMCID: PMC2121216 DOI: 10.1084/jem.20052388] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
West Nile virus (WNV) causes a severe infection of the central nervous system in several vertebrate animals including humans. Prior studies have shown that complement plays a critical role in controlling WNV infection in complement (C) 3(-/-) and complement receptor 1/2(-/-) mice. Here, we dissect the contributions of the individual complement activation pathways to the protection from WNV disease. Genetic deficiencies in C1q, C4, factor B, or factor D all resulted in increased mortality in mice, suggesting that all activation pathways function together to limit WNV spread. In the absence of alternative pathway complement activation, WNV disseminated into the central nervous system at earlier times and was associated with reduced CD8+ T cell responses yet near normal anti-WNV antibody profiles. Animals lacking the classical and lectin pathways had deficits in both B and T cell responses to WNV. Finally, and somewhat surprisingly, C1q was required for productive infection in the spleen but not for development of adaptive immune responses after WNV infection. Our results suggest that individual pathways of complement activation control WNV infection by priming adaptive immune responses through distinct mechanisms.
Collapse
Affiliation(s)
- Erin Mehlhop
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | |
Collapse
|
782
|
Affiliation(s)
- Fu-Shin X Yu
- Kresge Eye Institute/Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | | |
Collapse
|
783
|
Town T, Jeng D, Alexopoulou L, Tan J, Flavell RA. Microglia recognize double-stranded RNA via TLR3. THE JOURNAL OF IMMUNOLOGY 2006; 176:3804-12. [PMID: 16517751 DOI: 10.4049/jimmunol.176.6.3804] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Microglia are CNS resident innate immune cells of myeloid origin that become activated and produce innate proinflammatory molecules upon encountering bacteria or viruses. TLRs are a phylogenetically conserved diverse family of sensors for pathogen-associated molecular patterns that drive innate immune responses. We have recently shown that mice deficient in TLR3 (TLR3(-/-) mice) are resistant to lethal encephalitis and have reduced microglial activation after infection with West Nile virus, a retrovirus that produces dsRNA. We wished to determine whether microglia recognize dsRNA through the TLR3 pathway. In vitro, murine wild-type primary cultured microglia responded to synthetic dsRNA polyinosinic-polycytidylic acid (poly(I:C)) by increasing TLR3 and IFN-beta mRNA and by morphologic activation. Furthermore, wild-type microglia dose dependently secreted TNF-alpha and IL-6 after poly(I:C) challenge, whereas TLR3(-/-) microglia produced diminished cytokines. Activation of MAPK occurred in a time-dependent fashion following poly(I:C) treatment of wild-type microglia, but happened with delayed kinetics in TLR3(-/-) microglia. As an in vivo model of encephalitis, wild-type or TLR3(-/-) mice were injected intracerebroventricularly with poly(I:C) or LPS, and microglial activation was assessed by cell surface marker or phospho-MAPK immunofluorescence. After intracerebroventricular injection of poly(I:C), microgliosis was clearly evident in wild-type mice but was nearly absent in TLR3(-/-) animals. When taken together, our results demonstrate that microglia recognize dsRNA through TLR3 and associated signaling molecules and suggest that these cells are key sensors of dsRNA-producing viruses that may invade the CNS.
Collapse
Affiliation(s)
- Terrence Town
- Section of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA
| | | | | | | | | |
Collapse
|
784
|
Shirato K, Miyoshi H, Kariwa H, Takashima I. The kinetics of proinflammatory cytokines in murine peritoneal macrophages infected with envelope protein-glycosylated or non-glycosylated West Nile virus. Virus Res 2006; 121:11-6. [PMID: 16632038 DOI: 10.1016/j.virusres.2006.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 03/10/2006] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
The envelope (E) protein glycosylation status of the New York strain of West Nile (WN) virus is an important determinant of virus neuroinvasiveness. To elucidate the determinant of the difference between E protein-glycosylated and non-glycosylated WN virus infections, the cytokine expression of murine peritoneal macrophages infected with each virus was examined. Tumor necrosis factor (TNF) alpha and interleukin (IL)-1beta were up-regulated with replication of the E protein-glycosylated virus. Interferon (IFN) beta and IL-6 were up-regulated with the clearance of both viruses. These results suggest that TNFalpha and IL-1beta expression are related to the virulence of E protein-glycosylated WN virus.
Collapse
Affiliation(s)
- Kazuya Shirato
- Laboratory of Public Health, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Sapporo, 060-0818, Japan
| | | | | | | |
Collapse
|
785
|
Scherbik SV, Paranjape JM, Stockman BM, Silverman RH, Brinton MA. RNase L plays a role in the antiviral response to West Nile virus. J Virol 2006; 80:2987-99. [PMID: 16501108 PMCID: PMC1395436 DOI: 10.1128/jvi.80.6.2987-2999.2006] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Alleles at the Flv locus determine disease outcome after a flavivirus infection in mice. Although comparable numbers of congenic resistant and susceptible mouse embryo fibroblasts (MEFs) are infected by the flavivirus West Nile virus (WNV), resistant MEFs produce approximately 100- to 150-fold lower titers than susceptible ones and flavivirus titers in the brains of resistant and susceptible animals can differ by >10,000-fold. The Flv locus was previously identified as the 2'-5' oligoadenylate synthetase 1b (Oas1b) gene. Oas gene expression is up-regulated by interferon (IFN), and after activation by double-stranded RNA, some mouse synthetases produce 2-5A, which activates latent RNase L to degrade viral and cellular RNAs. To determine whether the lower levels of intracellular flavivirus genomic RNA from resistant mice detected in cells at all times after infection were mediated by RNase L, RNase L activity levels in congenic resistant and susceptible cells were compared. Similar moderate levels of RNase L activation by transfected 2-5A were observed in both types of uninfected cells. After WNV infection, the mRNAs of IFN-beta and three Oas genes were up-regulated to similar levels in both types of cells. However, significant levels of RNase L activity were not detected until 72 h after WNV infection and the patterns of viral RNA cleavage products generated were similar in both types of cells. When RNase L activity was down-regulated in resistant cells via stable expression of a dominant negative RNase L mutant, approximately 5- to 10-times-higher yields of WNV were produced. Similarly, about approximately 5- to 10-times-higher virus yields were produced by susceptible C57BL/6 RNase L-/- cells compared to RNase L+/+ cells that were either left untreated or pretreated with IFN and/or poly(I) . poly(C). The data indicate that WNV genomic RNA is susceptible to RNase L cleavage and that RNase L plays a role in the cellular antiviral response to flaviviruses. The results suggest that RNase L activation is not a major component of the Oas1b-mediated flavivirus resistance phenotype.
Collapse
Affiliation(s)
- Svetlana V Scherbik
- Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, Georgia 30302-4010, USA
| | | | | | | | | |
Collapse
|
786
|
Fredericksen BL, Gale M. West Nile virus evades activation of interferon regulatory factor 3 through RIG-I-dependent and -independent pathways without antagonizing host defense signaling. J Virol 2006; 80:2913-23. [PMID: 16501100 PMCID: PMC1395472 DOI: 10.1128/jvi.80.6.2913-2923.2006] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The ability of viruses to control and/or evade the host antiviral response is critical to the establishment of a productive infection. We have previously shown that West Nile virus NY (WNV-NY) delays activation of interferon regulatory factor 3 (IRF-3), a transcription factor critical to the initiation of the antiviral response. Here we demonstrate that the delayed activation of IRF-3 is essential for WNV-NY to achieve maximum virus production. Furthermore, WNV-NY utilizes a unique mechanism to control activation of IRF-3. In contrast to many other viruses that impose a nonspecific block to the IRF-3 pathway, WNV-NY eludes detection by the host cell at early times postinfection. To better understand this process, we assessed the role of the pathogen recognition receptor (PRR) retinoic acid-inducible gene I (RIG-I) in sensing WNV-NY infection. RIG-I null mouse embryo fibroblasts (MEFs) retained the ability to respond to WNV-NY infection; however, the onset of the host response was delayed compared to wild-type (WT) MEFs. This suggests that RIG-I is involved in initially sensing WNV-NY infection, while other PRRs sustain and/or amplify the host response later in infection. The delayed initiation of the host response correlated with an increase in WNV-NY replication in RIG-I null MEFs compared to WT MEFs. Our data suggest that activation of the host response by RIG-I early in infection is important for controlling replication of WNV-NY. Furthermore, pathogenic strains of WNV may have evolved to circumvent stimulation of the host response until after replication is well under way.
Collapse
Affiliation(s)
- Brenda L Fredericksen
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, USA
| | | |
Collapse
|
787
|
Zhao J, Kong HJ, Li H, Huang B, Yang M, Zhu C, Bogunovic M, Zheng F, Mayer L, Ozato K, Unkeless J, Xiong H. IRF-8/Interferon (IFN) Consensus Sequence-binding Protein Is Involved in Toll-like Receptor (TLR) Signaling and Contributes to the Cross-talk between TLR and IFN-γ Signaling Pathways. J Biol Chem 2006; 281:10073-80. [PMID: 16484229 DOI: 10.1074/jbc.m507788200] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Toll-like receptor (TLR) and interferon-gamma (IFN-gamma) signaling pathways are important for both innate and adaptive immune responses. However, the cross-talk between these two signaling pathways is incompletely understood. Here we show that IFN-gamma and LPS synergistically induce the expression of proinflammatory factors, including interleukin-1 (IL-1), IL-6, IL-12, NO, and tumor necrosis factor-alpha (TNF-alpha). Comparable synergism was observed between IFN-gamma and peptidoglycan (PGN; a TLR2 ligand) and poly(I:C) (a TLR3 ligand) in the induction of IL-12 promoter activity. IFN-gamma enhanced lipopolysaccharide (LPS)-induced ERK and JNK phosphorylation but had no effect on LPS-induced NF-kappaB activation. Interestingly, we found that IRF-8-/- macrophages were impaired in the activation of LPS-induced ERK and JNK and the production of proinflammatory cytokines induced by LPS or IFN-gamma plus LPS. Retroviral transduction of IRF-8 into IRF-8-/- macrophages rescued ERK and JNK activation. Furthermore, co-immunoprecipitation experiments show that IRF-8 physically interacts with TRAF6 at a binding site between amino acid residues 356 and 305 of IRF-8. Transfection of IRF-8 enhanced TRAF6 ubiquitination, which is consistent with a physical interaction of IRF-8 with TRAF6. Taken together, the results suggest that the interaction of IRF-8 with TRAF6 modulates TLR signaling and may contribute to the cross-talk between IFN-gamma and TLR signal pathways.
Collapse
Affiliation(s)
- Jie Zhao
- Immunobiology Center, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, NY 10029, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
788
|
Kawai T, Akira S. Innate immune recognition of viral infection. Nat Immunol 2006; 7:131-7. [PMID: 16424890 DOI: 10.1038/ni1303] [Citation(s) in RCA: 1425] [Impact Index Per Article: 79.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Accepted: 11/14/2005] [Indexed: 11/09/2022]
Abstract
Induction of the antiviral innate immune response depends on recognition of viral components by host pattern-recognition receptors. Members of the Toll-like receptor family have emerged as key sensors that recognize viral components such as nucleic acids. Toll-like receptor signaling results in the production of type I interferon and inflammatory cytokines and leads to dendritic cell maturation and establishment of antiviral immunity. Cells also express cytoplasmic RNA helicases that function as alternative pattern-recognition receptors through recognition of double-stranded RNA produced during virus replication. These two classes of pattern-recognition receptor molecules are expressed in different intracellular compartments and induce type I interferon responses via distinct signaling pathways.
Collapse
Affiliation(s)
- Taro Kawai
- Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Suita, Osaka 565-0871, Japan
| | | |
Collapse
|
789
|
Abstract
Microorganisms that invade a vertebrate host are initially recognized by the innate immune system through germline-encoded pattern-recognition receptors (PRRs). Several classes of PRRs, including Toll-like receptors and cytoplasmic receptors, recognize distinct microbial components and directly activate immune cells. Exposure of immune cells to the ligands of these receptors activates intracellular signaling cascades that rapidly induce the expression of a variety of overlapping and unique genes involved in the inflammatory and immune responses. New insights into innate immunity are changing the way we think about pathogenesis and the treatment of infectious diseases, allergy, and autoimmunity.
Collapse
Affiliation(s)
- Shizuo Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
| | | | | |
Collapse
|
790
|
Borisevich V, Seregin A, Nistler R, Mutabazi D, Yamshchikov V. Biological properties of chimeric West Nile viruses. Virology 2006; 349:371-81. [PMID: 16545851 DOI: 10.1016/j.virol.2006.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Revised: 01/18/2006] [Accepted: 02/10/2006] [Indexed: 12/14/2022]
Abstract
Recently, we have described a lineage 2 attenuated WN virus suitable for the development of a live WN vaccine. To design vaccine candidates with an improved immunogenicity, we assembled an infectious clone of the NY99 strain and created several chimeric constructs with reciprocal exchanges of structural protein genes between attenuated W956 and virulent NY99 and investigated their biological properties. Our data indicated that, while the growth rates of NY99 and chimeric viruses in tissue culture are determined primarily by properties of the structural proteins, determinants responsible for a highly cytopathic phenotype of NY99 or lack thereof for W956 are located within the nonstructural protein region of the WN genome. The high virulence of NY99 and the attenuated phenotype of W956 were found to be associated with determinants in the nonstructural region. Chimeric viruses carrying the NY99 structural proteins were attenuated in neuroinvasiveness and demonstrated an immunogenicity superior to W956.
Collapse
Affiliation(s)
- Victoria Borisevich
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave., Lawrence, KS 66045, USA
| | | | | | | | | |
Collapse
|
791
|
Abstract
The remarkable discovery of the Toll-like receptors (TLRs) over the past 5 years has opened up an entirely new era in the understanding of the molecular events that initiate the inflammatory response. These type 1 transmembrane receptors are expressed on a large number of immune cells as well as epithelial cells and play an essential role in the activation of the innate immune response to microbial pathogens. They impact on adaptive immune reactions and contribute to the initiation and maintenance of the inflammatory response to a multitude of potential microbial pathogens through recognition of pathogen-associated molecular patterns. TLRs also interact with a variety of endogenous human ligands and influence the activity of a wide range of tissues and cell processes. Among the common and important processes in which TLRs play a role are asthma, acute respiratory distress syndrome, cardiac ischaemia, coronary artery disease, ventricular remodelling, vascular collapse, inflammatory bowel disease, acute tubular necrosis, psoriasis, rheumatoid arthritis, pre-term birth, fertility, cancer angiogenesis and transplant rejection. From this strikingly diverse list, many important opportunities for disease modification through TLR manipulation can be imagined. Their role as potential targets for therapeutic intervention is just beginning to be appreciated, and the current status of these treatment strategies is reviewed in this article.
Collapse
Affiliation(s)
- Patricia Cristofaro
- Infectious Disease Division, Brown Medical School, Providence, Rhode Island, USA.
| | | |
Collapse
|
792
|
Park C, Lee S, Cho IH, Lee HK, Kim D, Choi SY, Oh SB, Park K, Kim JS, Lee SJ. TLR3-mediated signal induces proinflammatory cytokine and chemokine gene expression in astrocytes: differential signaling mechanisms of TLR3-induced IP-10 and IL-8 gene expression. Glia 2006; 53:248-56. [PMID: 16265667 DOI: 10.1002/glia.20278] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Viral infection is one of the leading causes of brain encephalitis and meningitis. Recently, it was reported that Toll-like receptor-3 (TLR3) induces a double-stranded RNA (dsRNA)-mediated inflammatory signal in the cells of the innate immune system, and studies suggested that dsRNA may induce inflammation in the central nervous system (CNS) by activating the CNS-resident glial cells. To explore further the connection between dsRNA and inflammation in the CNS, we have studied the effects of dsRNA stimulation in astrocytes. Our results show that the injection of polyinosinic-polycytidylic acid (poly(I:C)), a synthetic dsRNA, into the striatum of the mouse brain induces the activation of astrocytes and the expression of TNF-alpha, IFN-beta, and IP-10. Stimulation with poly(I:C) also induces the expression of these proinflammatory genes in primary astrocytes and in CRT-MG, a human astrocyte cell line. Furthermore, our studies on the intracellular signaling pathways reveal that poly(I:C) stimulation activates IkappaB kinase (IKK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) in CRT-MG. Pharmacological inhibitors of nuclear factor-kappaB (NF-kappaB), JNK, ERK, glycogen synthase kinase-3beta (GSK-3beta), and dsRNA-activated protein kinase (PKR) inhibit the expression of IL-8 and IP-10 in astrocytes, indicating that the activation of these signaling molecules is required for the TLR3-mediated chemokine gene induction. Interestingly, the inhibition of PI3 kinase suppressed the expression of IP-10, but upregulated the expression of IL-8, suggesting differential roles for PI3 kinase, depending on the target genes. These data suggest that the TLR3 expressed on astrocytes may initiate an inflammatory response upon viral infection in the CNS.
Collapse
Affiliation(s)
- Chanhee Park
- Program in Cellular and Molecular Neuroscience and Department of Oral Physiology, College of Dentistry,Seoul National University, Seoul, South Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
793
|
Sasai M, Matsumoto M, Seya T. The Kinase Complex Responsible for IRF-3–Mediated IFN-β Production in Myeloid Dendritic Cells (mDC). ACTA ACUST UNITED AC 2006; 139:171-5. [PMID: 16452304 DOI: 10.1093/jb/mvj025] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Type I interferons (IFN) IFN-alpha and -beta play a central role in the induction of antiviral immunity, which involves up-regulation or activation of a large number of IFN-inducible genes in host immune competent cells. Initial events in the antiviral response may occur in myeloid dendritic cells (mDCs), and the proteins expressed provoke early responses to cope with concomitant infection in the host. The participation of transcription factors IRF-3/7, AP1 and NF-kappaB in IFN-beta promoter activation in mDCs is well established. An initial trigger of this event is a viral dsRNA that is recognized by proteins with an RNA-binding motif. Toll-like receptor (TLR) 3 on membranes and RIG-Iin the cytoplasm are molecules with dsRNA-recognition ability. Our main aim in the present review is to describe how IRF-3 and/or NF-kappaB are activated through the initial recognition of dsRNA by these pattern-recognition receptors. By analogy to the trimolecular complex of IKKgamma, IKKalpha and IKKbeta, thus far, IRF-3-activated kinases have been reported to be kinase complexes with trimolecular assembly. Two kinases, TBK1 and IKKepsilon, are thought to be linked to regulatory subunit TANK or NAP1 with no kinase activity like IKKgamma. The TLR3 and RIG-I pathways converge upstream of IRF-3, possibly at NAP1, the regulatory subunit of IRF-3-activating kinase. Thus, a novel function of the regulatory subunit has emerged. These proteins are involved in the TLR3 and RIG-I pathways, and act as adapters bridging on the dsRNA-recognition unit and IRF-3-activating kinases in addition to their kinase-regulatory function. Here, we summarize the properties of regulatory subunits NAP1 and TANK, and the mode of activation of NF-kappaB and IRF-3 in conjunction with the unique properties of the TLR3 function.
Collapse
Affiliation(s)
- Miwa Sasai
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Sapporo 060-8638, Japan
| | | | | |
Collapse
|
794
|
Hayes EB, Gubler DJ. West Nile Virus: Epidemiology and Clinical Features of an Emerging Epidemic in the United States. Annu Rev Med 2006; 57:181-94. [PMID: 16409144 DOI: 10.1146/annurev.med.57.121304.131418] [Citation(s) in RCA: 231] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
West Nile virus (WNV) was first detected in North America in 1999 during an outbreak of encephalitis in New York City. Since then the virus has spread across North America and into Canada, Latin America, and the Caribbean. The largest epidemics of neuroinvasive WNV disease ever reported occurred in the United States in 2002 and 2003. This paper reviews new information on the epidemiology and clinical aspects of WNV disease derived from greatly expanded surveillance and research on WNV during the past six years.
Collapse
Affiliation(s)
- Edward B Hayes
- Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, USA.
| | | |
Collapse
|
795
|
Abstract
Multicellular organisms possess very sophisticated defense mechanisms that are designed to effectively counter the continual microbial insult of the environment within the vertebrate host. However, successful microbial pathogens have in turn evolved complex and efficient methods to overcome innate and adaptive immune mechanisms, which can result in disease or chronic infections. Although the various virulence strategies used by viral and bacterial pathogens are numerous, there are several general mechanisms that are used to subvert and exploit immune systems that are shared between these diverse microbial pathogens. The success of each pathogen is directly dependant on its ability to mount an effective anti-immune response within the infected host, which can ultimately result in acute disease, chronic infection, or pathogen clearance. In this review, we highlight and compare some of the many molecular mechanisms that bacterial and viral pathogens use to evade host immune defenses.
Collapse
Affiliation(s)
- B Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver, B.C. V6T 1Z4 Canada.
| | | |
Collapse
|
796
|
Chang TH, Liao CL, Lin YL. Flavivirus induces interferon-beta gene expression through a pathway involving RIG-I-dependent IRF-3 and PI3K-dependent NF-kappaB activation. Microbes Infect 2006; 8:157-71. [PMID: 16182584 DOI: 10.1016/j.micinf.2005.06.014] [Citation(s) in RCA: 184] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 06/09/2005] [Accepted: 06/10/2005] [Indexed: 02/07/2023]
Abstract
In this study, we found that infection with flaviviruses, such as Japanese encephalitis virus (JEV) and dengue virus serotype 2 (DEN-2), leads to interferon-beta (IFN-beta) gene expression in a virus-replication- and de novo protein-synthesis-dependent manner. NF-kappaB activation is essential for IFN-beta induction in JEV- and DEN-2-infected cells. However, these two viruses seem to preferentially target different members of the interferon regulatory factor (IRF) family. The activation of constitutively expressed IRF-3, characterized by slower gel mobility, dimer formation, and nuclear translocation, is more evident in JEV-infected cells. Other members of the IRF family, such as IRF-1 and IRF-7 are also induced by DEN-2, but not by JEV infection. The upstream molecules responsible for IRF-3 and NF-kappaB activation were further studied. Evidently, a cellular RNA helicase, retinoic acid-inducible gene I (RIG-I), and a cellular kinase, phosphatidylinositol-3 kinase (PI3K), are required for flavivirus-induced IRF-3 and NF-kappaB activation, respectively. Therefore, we suggest that JEV and DEN-2 initiate the host innate immune response through a molecular mechanism involving RIG-I/IRF-3 and PI3K/NF-kappaB signaling pathways.
Collapse
Affiliation(s)
- Tsung-Hsien Chang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | | | | |
Collapse
|
797
|
Shrestha B, Samuel MA, Diamond MS. CD8+ T cells require perforin to clear West Nile virus from infected neurons. J Virol 2006; 80:119-29. [PMID: 16352536 PMCID: PMC1317548 DOI: 10.1128/jvi.80.1.119-129.2006] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 10/05/2005] [Indexed: 11/20/2022] Open
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.
Collapse
Affiliation(s)
- Bimmi Shrestha
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, 660 South Euclid Ave., Box 8051, St. Louis, MO 63110, USA
| | | | | |
Collapse
|
798
|
Maródi L. Innate cellular immune responses in newborns. Clin Immunol 2005; 118:137-44. [PMID: 16377252 DOI: 10.1016/j.clim.2005.10.012] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 09/28/2005] [Accepted: 10/03/2005] [Indexed: 02/06/2023]
Abstract
Innate immunity assures the first line of defense against pathogenic microorganisms. Innate immune responses induced by bacteria, fungi, or viral replication are triggered by granulocytes, monocytes, macrophages, dentritic cells, and natural killer cells. Neonatal deficiency of innate cellular immunity includes a decreased production of interferons, IL-12/IL-23, and IL-18, and other proinflammatory cytokines, an impaired type-1 response of macrophages to IFN-gamma, the most potent macrophage-activating agent in vivo, and to lipopolysaccharide, the primary constituent of the outer membrane of Gram-negative bacteria. An increasing body of evidence suggests impaired responses of neonatal monocytes and macrophages to multiple TLR ligands. This review will discuss recent advances in understanding innate cellular immunity in human neonates, with respect to selected aspects of immune functions that may be related to increased susceptibility to infections. Components of TLR signaling and the immune consequence that may result from neonatal deficiencies will be highlighted. A better understanding of innate immunity can make the development of techniques possible by which physicians more accurately tailor prevention and treatment of neonatal infections.
Collapse
Affiliation(s)
- László Maródi
- Department of Infectiology and Pediatric Immunology, Medical and Health Science Center, University of Debrecen, Nagyerdei Krt. 98, H-4012 Debrecen, Hungary.
| |
Collapse
|
799
|
Kuno G, Chang GJJ. Biological transmission of arboviruses: reexamination of and new insights into components, mechanisms, and unique traits as well as their evolutionary trends. Clin Microbiol Rev 2005; 18:608-37. [PMID: 16223950 PMCID: PMC1265912 DOI: 10.1128/cmr.18.4.608-637.2005] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Among animal viruses, arboviruses are unique in that they depend on arthropod vectors for transmission. Field research and laboratory investigations related to the three components of this unique mode of transmission, virus, vector, and vertebrate host, have produced an enormous amount of valuable information that may be found in numerous publications. However, despite many reviews on specific viruses, diseases, or interests, a systematic approach to organizing the available information on all facets of biological transmission and then to interpret it in the context of the evolutionary process has not been attempted before. Such an attempt in this review clearly demonstrates tremendous progress made worldwide to characterize the viruses, to comprehend disease transmission and pathogenesis, and to understand the biology of vectors and their role in transmission. The rapid progress in molecular biologic techniques also helped resolve many virologic puzzles and yielded highly valuable data hitherto unavailable, such as characterization of virus receptors, the genetic basis of vertebrate resistance to viral infection, and phylogenetic evidence of the history of host range shifts in arboviruses. However, glaring gaps in knowledge of many critical subjects, such as the mechanism of viral persistence and the existence of vertebrate reservoirs, are still evident. Furthermore, with the accumulated data, new questions were raised, such as evolutionary directions of virus virulence and of host range. Although many fundamental questions on the evolution of this unique mode of transmission remained unresolved in the absence of a fossil record, available observations for arboviruses and the information derived from studies in other fields of the biological sciences suggested convergent evolution as a plausible process. Overall, discussion of the diverse range of theories proposed and observations made by many investigators was found to be highly valuable for sorting out the possible mechanism(s) of the emergence of arboviral diseases.
Collapse
Affiliation(s)
- Goro Kuno
- Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA.
| | | |
Collapse
|
800
|
Rothenfusser S, Goutagny N, DiPerna G, Gong M, Monks BG, Schoenemeyer A, Yamamoto M, Akira S, Fitzgerald KA. The RNA helicase Lgp2 inhibits TLR-independent sensing of viral replication by retinoic acid-inducible gene-I. THE JOURNAL OF IMMUNOLOGY 2005; 175:5260-8. [PMID: 16210631 DOI: 10.4049/jimmunol.175.8.5260] [Citation(s) in RCA: 459] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The paramyxovirus Sendai (SV), is a well-established inducer of IFN-alphabeta gene expression. In this study we show that SV induces IFN-alphabeta gene expression normally in cells from mice with targeted deletions of the Toll-IL-1 resistance domain containing adapters MyD88, Mal, Toll/IL-1R domain-containing adaptor inducing IFN-beta (TRIF), and TRIF-related adaptor molecule TLR3, or the E3 ubiquitin ligase, TNFR-associated factor 6. This TLR-independent induction of IFN-alphabeta after SV infection is replication dependent and mediated by the RNA helicase, retinoic acid-inducible gene-I (RIG-I) and not the related family member, melanoma differentiation-associated gene 5. Furthermore, we characterize a RIG-I-like RNA helicase, Lgp2. In contrast to RIG-I or melanoma differentiation-associated gene 5, Lgp2 lacks signaling caspase recruitment and activation domains. Overexpression of Lgp2 inhibits SV and Newcastle disease virus signaling to IFN-stimulated regulatory element- and NF-kappaB-dependent pathways. Importantly, Lgp2 does not prevent TLR3 signaling. Like RIG-I, Lgp2 binds double-stranded, but not single-stranded, RNA. Quantitative PCR analysis demonstrates that Lgp2 is present in unstimulated cells at a lower level than RIG-I, although both helicases are induced to similar levels after virus infection. We propose that Lgp2 acts as a negative feedback regulator of antiviral signaling by sequestering dsRNA from RIG-I.
Collapse
Affiliation(s)
- Simon Rothenfusser
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | | | | | | | | | | | | | | | | |
Collapse
|