Yi-Liang Zhang1, Ying-Jun Guo, Shu-Han Sun. 1. Department of Medical Genetics, Second Military Medical University, 800 Xiang'Yin Road, 200433 Shanghai, China.
Abstract
BACKGROUND/AIMS: Innate immune responses to HCV infection are triggered through host recognition of pathogen-associated molecular patterns. Interferons are critical for the protection against HCV infection. However, the pathways linking virus recognition to IFN induction remain poorly understood. METHODS: Immune cells and Huh-7 cells were infected with HCV cell culture (HCVcc) or transfected with HCV-derived immunostimulatory RNA oligonucleotides (ORNs), and immune activation was assessed. RESULTS: We found that HCVcc suppressed immune responses because the HCVcc protein impaired the PBMC and pDC responses. However, HCVcc genomic RNA had an immunostimulatory effect. HCV encodes G/U-rich ssRNA TLR7 ligands that significantly activate innate immunity, and induced IFN-alpha production. Moreover, HCV-derived ORNs also activated IRF7 and NF-kappaB in Huh-7 cells. In particular, the HCV 3'-UTR strongly induced cytokine production. Different lengths of polyuridine tract in the 3'-UTR of different HCV strains induced IFN-alpha production. These data demonstrate that the HCV-specific G/U fragment is a motif sequence, and is recognized by TLR7 as a PAMP. The requirement for TLR7 to recognize HCV RNA was confirmed using specific inhibitors, RNAi and by TLR7overexpression. CONCLUSION: These results provide an insight into the development of immune adjuvant for vaccines and for the production of new antiviral drugs.
BACKGROUND/AIMS: Innate immune responses to HCV infection are triggered through host recognition of pathogen-associated molecular patterns. Interferons are critical for the protection against HCV infection. However, the pathways linking virus recognition to IFN induction remain poorly understood. METHODS: Immune cells and Huh-7 cells were infected with HCV cell culture (HCVcc) or transfected with HCV-derived immunostimulatory RNA oligonucleotides (ORNs), and immune activation was assessed. RESULTS: We found that HCVcc suppressed immune responses because the HCVcc protein impaired the PBMC and pDC responses. However, HCVcc genomic RNA had an immunostimulatory effect. HCV encodes G/U-rich ssRNA TLR7 ligands that significantly activate innate immunity, and induced IFN-alpha production. Moreover, HCV-derived ORNs also activated IRF7 and NF-kappaB in Huh-7 cells. In particular, the HCV 3'-UTR strongly induced cytokine production. Different lengths of polyuridine tract in the 3'-UTR of different HCV strains induced IFN-alpha production. These data demonstrate that the HCV-specific G/U fragment is a motif sequence, and is recognized by TLR7 as a PAMP. The requirement for TLR7 to recognize HCV RNA was confirmed using specific inhibitors, RNAi and by TLR7overexpression. CONCLUSION: These results provide an insight into the development of immune adjuvant for vaccines and for the production of new antiviral drugs.
Authors: Kevin B Walsh; John R Teijaro; Elina I Zuniga; Megan J Welch; Daniel M Fremgen; Shawn D Blackburn; Karl F von Tiehl; E John Wherry; Richard A Flavell; Michael B A Oldstone Journal: Cell Host Microbe Date: 2012-06-14 Impact factor: 21.023
Authors: Feng Qian; Christopher R Bolen; Chunxia Jing; Xiaomei Wang; Wei Zheng; Hongyu Zhao; Erol Fikrig; R Douglas Bruce; Steven H Kleinstein; Ruth R Montgomery Journal: Clin Vaccine Immunol Date: 2012-12-05