title: Activation of Toll-like receptor 3 impairs the dengue virus serotype 2 replication through induction of IFN-β in cultured hepatoma cells.
abstract: Toll-like receptors (TLRs) play an important role in innate immunity against invading pathogens. Although TLR signaling has been indicated to protect cells from infection of several viruses, the role of TLRs in Dengue virus (DENV) replication is still unclear. In the present study, we examined the replication of DENV serotype 2 (DENV2) by challenging hepatoma cells HepG2 with different TLR ligands. Activation of TLR3 showed an antiviral effect, while pretreatment of other TLR ligands (including TLR1/2, TLR2/6, TLR4, TLR5 or TLR7/8) did not show a significant effect. TLR3 ligand poly(I:C) treatment prior to viral infection or simultaneously, but not post-treatment, significantly down-regulated virus replication. Pretreatment with poly(I:C) reduced viral mRNA expression and viral staining positive cells, accompanying an induction of the type I interferon (IFN-β) and type III IFN (IL-28A/B). Intriguingly, neutralization of IFN-β alone successfully restored the poly(I:C)-inhibited replication of DENV2. The poly(I:C)-mediated effects, including IFN induction and DENV2 suppression, were significantly reversed by IKK inhibitor, further suggesting that IFN-β is the dominant factor involved in the poly(I:C) mediated antiviral effect. Our study presented the first evidence to show that activation of TLR3 is effective in blocking DENV2 replication via IFN-β, providing an experimental clue that poly(I:C) may be a promising immunomodulatory agent against DENV infection and might be applicable for clinical prevention.
authors.affiliation: Department of Immunology, Institute of Immunology, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zhaoduan
authors.initials: Z
authors.lastname: Liang
authors.forename: Siyu
authors.initials: S
authors.lastname: Wu
authors.forename: Yuye
authors.initials: Y
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: He
authors.forename: Minhao
authors.initials: M
authors.lastname: Wu
authors.forename: Lifang
authors.initials: L
authors.lastname: Jiang
authors.forename: Lianqiang
authors.initials: L
authors.lastname: Feng
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
mesh_terms: D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D003716:Dengue Virus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D016899:Interferon-beta / Q000096:biosynthesis*; D008024:Ligands; D008113:Liver Neoplasms / Q000473:pathology*; D008856:Microscopy, Fluorescence; D011070:Poly I-C / Q000494:pharmacology; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051196:Toll-Like Receptor 3 / Q000378:metabolism / Q000502:physiology*; D014779:Virus Replication / Q000502:physiology*
chemical_list: D017931:DNA Primers; D008024:Ligands; D012367:RNA, Viral; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D016899:Interferon-beta; D011070:Poly I-C