Project description:Discrimination between self vs. non-self and adequate response to infection and tissue damage are fundamental functions of the immune system. The rapid and global spread of known and emerging viruses is a testament that the timely detection of viral pathogens that reproduce within host cells, presents a formidable challenge to the immune system. To gain access to a proper reproductive niche, many pathogens travel via the host vasculature and therefore become exposed to humoral factors of the innate immune system. Although a cascade of coagulation factors plays a fundamental role in host defense for “living fossils” such as horseshoe crabs (Xiphosurida spp), the role of the coagulation system in activation of innate responses to pathogens in higher organisms remains unclear. When human type C adenovirus (HAdv) enters the circulation, 240 copies of coagulation factor X (FX) bind to the virus particle with picomolar affinity. Here, using molecular dynamics flexible fitting (MDFF) and high resolution cryo-electron microscopy (cryo-EM), we defined the interface between the HAdv5 hexon protein and FX at pseudo-atomic level. Based on this structural data, we introduced a single amino acid substitution, T424A, in the hexon that completely abrogated FX interaction with the virus. In vivo genome-wide transcriptional profiling revealed that FX-binding-ablated virus failed to activate a distinct network of the early response genes, whose expression depends on transcription factor NFKB1. Deconvolution of the signaling network responsible for early gene activation showed that the FX-HAdv complex triggers MyD88/TRIF/TRAF6 signaling upon activation of toll-like receptor 4 (TLR4) that serves as a principal sensor of FX-virus complex in vivo. Our study implicates host factor “decoration” of the virus as a mechanism to trigger innate immune sensor that respond to a misplacement of coagulation FX from the blood into intracellular macrophage compartments upon virus entry into the cell. Our results further the mounting evidence of evolutionary conservation between the coagulation system and innate immunity. Two strains of mice, C57BL/6, and Il1r1-/- deficient. Mice were challenged with wild type HAdv5 or HAdv5-based vectors.

Project description:Discrimination between self vs. non-self and adequate response to infection and tissue damage are fundamental functions of the immune system. The rapid and global spread of known and emerging viruses is a testament that the timely detection of viral pathogens that reproduce within host cells, presents a formidable challenge to the immune system. To gain access to a proper reproductive niche, many pathogens travel via the host vasculature and therefore become exposed to humoral factors of the innate immune system. Although a cascade of coagulation factors plays a fundamental role in host defense for “living fossils” such as horseshoe crabs (Xiphosurida spp), the role of the coagulation system in activation of innate responses to pathogens in higher organisms remains unclear. When human type C adenovirus (HAdv) enters the circulation, 240 copies of coagulation factor X (FX) bind to the virus particle with picomolar affinity. Here, using molecular dynamics flexible fitting (MDFF) and high resolution cryo-electron microscopy (cryo-EM), we defined the interface between the HAdv5 hexon protein and FX at pseudo-atomic level. Based on this structural data, we introduced a single amino acid substitution, T424A, in the hexon that completely abrogated FX interaction with the virus. In vivo genome-wide transcriptional profiling revealed that FX-binding-ablated virus failed to activate a distinct network of the early response genes, whose expression depends on transcription factor NFKB1. Deconvolution of the signaling network responsible for early gene activation showed that the FX-HAdv complex triggers MyD88/TRIF/TRAF6 signaling upon activation of toll-like receptor 4 (TLR4) that serves as a principal sensor of FX-virus complex in vivo. Our study implicates host factor “decoration” of the virus as a mechanism to trigger innate immune sensor that respond to a misplacement of coagulation FX from the blood into intracellular macrophage compartments upon virus entry into the cell. Our results further the mounting evidence of evolutionary conservation between the coagulation system and innate immunity.

Project description:BackgroundProtection against the influenza virus by a specific antibody is relatively strain specific; meanwhile broader immunity may be conferred by cell-mediated immune response to the conserved epitopes across influenza virus subtypes. A universal broad-spectrum influenza vaccine which confronts not only seasonal influenza virus, but also avian influenza H5N1 virus is promising.MethodsThis study determined the specific and cross-reactive T cell responses against the highly pathogenic avian influenza A (H5N1) virus in four survivors and 33 non-H5N1 subjects including 10 H3N2 patients and 23 healthy individuals. Ex vivo IFN-γ ELISpot assay using overlapping peptides spanning the entire nucleoprotein (NP), matrix (M) and hemagglutinin (HA) derived from A/Thailand/1(KAN-1)/2004 (H5N1) virus was employed in adjunct with flow cytometry for determining T cell functions. Microneutralization (microNT) assay was performed to determine the status of previous H5N1 virus infection.ResultsIFN-γ ELISpot assay demonstrated that survivors nos. 1 and 2 had markedly higher T cell responses against H5N1 NP, M and HA epitopes than survivors nos. 3 and 4; and the magnitude of T cell responses against NP were higher than that of M and HA. Durability of the immunoreactivity persisted for as long as four years after disease onset. Upon stimulation by NP in IFN-γ ELISpot assay, 60% of H3N2 patients and 39% of healthy subjects exhibited a cross-reactive T cell response. The higher frequency and magnitude of responses in H3N2 patients may be due to blood collection at the convalescent phase of the patients. In H5N1 survivors, the effector peptide-specific T cells generated from bulk culture PBMCs by in vitro stimulation displayed a polyfunction by simultaneously producing IFN-γ and TNF-α, together with upregulation of CD107a in recognition of the target cells pulsed with peptide or infected with rVac-NP virus as investigated by flow cytometry.ConclusionsThis study provides an insight into the better understanding on the homosubtypic and heterosubtypic T cell-mediated immune responses in H5N1 survivors and non-H5N1 subjects. NP is an immunodominant target of cross-recognition owing to its high conservancy. Therefore, the development of vaccine targeting the conserved NP may be a novel strategy for influenza vaccine design.

Dataset Information

Hemagglutinin from the H5N1 virus activates Janus kinase 3 to dysregulate innate immunity.

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Hemagglutinin from the H5N1 virus activates Janus kinase 3 to dysregulate innate immunity.

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