title: Toll-like receptor 9-mediated recognition of Herpes simplex virus-2 by plasmacytoid dendritic cells.
abstract: Plasmacytoid dendritic cells (pDCs) have been identified as a potent secretor of the type I interferons (IFNs) in response to CpG as well as several viruses. In this study, we examined the molecular mechanism of virus recognition by pDCs. First, we demonstrated that the CD11c+Gr-1intB220+ pDCs from mouse bone marrow secreted high levels of IFN-alpha in response to either live or UV-inactivated Herpes simplex virus-2 (HSV-2). Next, we identified that IFN-alpha secretion by pDCs required the expression of the adaptor molecule MyD88, suggesting the involvement of a Toll-like receptor (TLR) in HSV-2 recognition. To test whether a TLR mediates HSV-2-induced IFN-alpha secretion from pDCs, various knockout mice were examined. These experiments revealed a clear requirement for TLR9 in this process. Further, we demonstrated that purified HSV-2 DNA can trigger IFN-alpha secretion from pDCs and that inhibitory CpG oligonucleotide treatment diminished HSV-induced IFN-alpha secretion by pDCs in a dose-dependent manner. The recognition of HSV-2 by TLR9 was mediated through an endocytic pathway that was inhibited by chloroquine or bafilomycin A1. The strict requirement for TLR9 in IFN-alpha secretion was further confirmed by the inoculation of HSV-2 in vivo. Therefore, these results demonstrate a novel mechanism whereby the genomic DNA of a virus can engage TLR9 and result in the secretion of IFN-alpha by pDCs.
authors.affiliation: Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lund
authors.forename: Ayuko
authors.initials: A
authors.lastname: Sato
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Ruslan
authors.initials: R
authors.lastname: Medzhitov
authors.forename: Akiko
authors.initials: A
authors.lastname: Iwasaki
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D018899:CpG Islands; D004268:DNA-Binding Proteins / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005260:Female; D018258:Herpesvirus 2, Human / Q000276:immunology*; D006801:Humans; D016898:Interferon-alpha / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface / Q000276:immunology*; D011971:Receptors, Immunologic / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D051217:Toll-Like Receptor 9
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D004268:DNA-Binding Proteins; D016898:Interferon-alpha; C507779:MYD88 protein, human; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C495371:TLR9 protein, human; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9