The virion host shut-off (vhs) protein blocks a TLR-independent pathway of herpes simplex virus type 1 recognition in human and mouse dendritic cells

• Published in: PloS one Vol. 5; no. 2; p. e8684
• Main Authors: Cotter, Christopher R, Nguyen, Marie L, Yount, Jacob S, López, Carolina B, Blaho, John A, Moran, Thomas M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18.02.2010; Public Library of Science (PLoS)
• Subjects: Activation; Animals; Antigens; Blockage; Cell activation; Cells, Cultured; Cercopithecus aethiops; Cytokines; Cytokines - genetics; Cytokines - metabolism; Dendritic cells; Dendritic Cells - cytology; Dendritic Cells - metabolism; Dendritic Cells - virology; Enzyme-Linked Immunosorbent Assay; Gene Expression; Herpes simplex; Herpes simplex virus; Herpes viruses; Herpesvirus 1, Human - genetics; Herpesvirus 1, Human - physiology; Host-Pathogen Interactions; Humans; Immunology; Immunology/Antigen Processing and Recognition; Immunology/Immune Response; Immunology/Immunity to Infections; Immunology/Innate Immunity; Infection; Infections; Inflammation; Medicine; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutation; MyD88 protein; Newcastle disease; Newcastle disease virus - genetics; Newcastle disease virus - physiology; Pathways; Protein synthesis; Proteins; Recognition; Replication; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleases - genetics; Ribonucleases - physiology; Sendai virus - genetics; Sendai virus - physiology; Signal Transduction; Signaling; Tegument; TLR3 protein; Toll-Like Receptor 3 - agonists; Toll-Like Receptor 3 - genetics; Toll-Like Receptor 3 - physiology; Toll-like receptors; Vero Cells; Vhs protein; Viral proteins; Viral Proteins - genetics; Viral Proteins - physiology; Virions; Virus Replication; Viruses; New York; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0008684

Molecular pathways underlying the activation of dendritic cells (DCs) in response to Herpes Simplex Virus type 1 (HSV-1) are poorly understood. Removal of the HSV virion host shut-off (vhs) protein relieves a block to DC activation observed during wild-type infection. In this study, we utilized a potent DC stimulatory HSV-1 recombinant virus lacking vhs as a tool to investigate the mechanisms involved in the activation of DCs by HSV-1. We report that the release of pro-inflammatory cytokines by conventional DC (cDC) during HSV-1 infection is triggered by both virus replication-dependent and replication-independent pathways. Interestingly, while vhs is capable of inhibiting the release of cytokines during infection of human and mouse cDCs, the secretion of cytokines by plasmacytoid DC (pDC) is not affected by vhs. These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein. Using cDCs isolated from mice deficient in both the TLR adaptor protein MyD88 and TLR3, we show that HSV-1 and the vhs-deleted virus can activate cDCs independently of TLR signaling. In addition, virion-associated vhs fails to block cDC activation in response to treatment with TLR agonists, but it efficiently blocked cDC activation triggered by the paramyxoviruses Sendai Virus (SeV) and Newcastle Disease Virus (NDV). This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs. Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.