Project description:Influenza A virus is a kind of single negative-stranded RNA virus which belongs to the Orthomyxoviridae family. It can cause localized outbreak or worldwide epidemic in a short time for its great contagiosity, fast spread speed and a wide range of host, and H1N1 influenza virus is a strong pathogenic subtype of influenza A virus. Influenza A virus infection has been shown to alter miRNA expression both in cultured cells and in animal models. We used microRNA microarrays to detail the programme of microRNA expression and identified distinct classes of differentially regulated microRNAs during this process.
Project description:Influenza A virus is mainly transmitted through the respiratory route and can cause severe illness in humans. Proteins encoded by influenza A virus can interact with cellular factors and dysregulate host biological processes to facilitate viral replication and pathogenicity. The influenza viral PA protein is not only a subunit of influenza viral polymerase but also a virulence factor involved in pathogenicity during infection. To explore the role of the influenza virus PA protein in regulating host biological processes, we conducted immunoprecipitation and LC-MS/MS to globally identify cellular factors that interact with the PA proteins of the influenza A H1N1, 2009 pandemic H1N1, H3N2, and H7N9 viruses. The results demonstrated that proteins located in the mitochondrion, proteasome, and nucleus are associated with the PA protein. We further discovered that the PA protein is located in mitochondria by immunofluorescence and mitochondrial fractionation and that overexpression of the PA protein reduces mitochondrial respiration. In addition, our results revealed the interaction between PA and the mitochondrial matrix protein PYCR2 and the antiviral role of PYCR2 during influenza A virus replication. Moreover, we found that the PA protein could also trigger autophagy and disrupt mitochondrial homeostasis. Overall, our research revealed the impacts of the influenza A virus PA protein on mitochondrial function and autophagy.
Project description:The 1918 influenza pandemic was unusually severe, resulting in about 50 million deaths worldwide. A reconstructed version of the 1918 (H1N1) virus has been shown to also highly pathogenic in mice; however, the potential virulence and pathogenicity of the 1918 virus in nonhuman primates in unknown. In these studies, we demonstrate that the 1918 virus caused a highly pathogenic respiratory infection in a cynomolgus macaque model that culminated in acute respiratory distress and a fatal outcome. To characterize the global gene expression host response, oligonulceotide microarray analysis was performed on RNA isolated from the bronchus of macaques infected with either the 1918 virus or a humanized contemporary H1N1 influenza virus (A/Kawasaki/173/01). These experiments showed that infected animals mounted an immune response, characterized by dysregulation of the antiviral response, that was insufficient for protection, suggesting that atypical host innate immune responses may contribute to lethality.
Project description:Vaccine development involves time-consuming and expensive evaluation of candidate vaccines in animal models. As mediators of both innate and adaptive immune responses dendritic cells (DCs) are considered to be highly important for vaccine performance. Here we evaluated in how far the response of DCs to a vaccine in vitro is in line with the immune response the vaccine evokes in vivo. To this end, we investigated the response of murine bone marrow-derived DCs to whole inactivated virus (WIV) and subunit (SU) influenza vaccine preparations. These vaccine preparations were chosen because they differ in the immune response they evoke in mice with WIV being superior to SU vaccine through induction of higher virus-neutralizing antibody titers and a more favorable Th1-skewed response phenotype. To evaluate if in vivo immunogenicity is reflected by DC reactions in vitro we studied the gene expression signature of murine bone-marrow-derived conventional DCs (cDCs) upon stimulation with WIV or SU influenza vaccine or, for reasons of comparison, with live influenza virus. Dendritic cells stimulated with PBS served as a control. Gene expression analysis was performed on samples 4, 12 and 24 hours after the start of stimulation.
Project description:Circular RNAs (circRNAs) participate in regulating many biological processes. However, their roles in influenza A virus (IAV) pathogenicity are largely unknown. Here, we analyzed the expression profile of circRNAs in the H1N1-infected cells by high-throughput sequencing
Project description:Non-human primates are the animals closest to humans for use in influenza A virus challenge studies, in terms of their phylogenetic relatedness, physiology and immune systems. Previous studies have shown that cynomolgus macaques (Macaca fascicularis) are permissive for infection with H1N1pdm influenza virus. These studies have typically used combined challenge routes, with the majority being intra-tracheal delivery, and high doses of virus (> 107 infectious units). This paper describes the outcome of novel challenge routes (inhaled aerosol, intra-nasal instillation) and low to moderate doses (103 to 106 plaque forming units) of H1N1pdm virus in cynomolgus macaques. All 4 challenge groups showed sero-conversion and evidence of virus replication, although the disease was sub-clinical. Intra-nasal challenge led to an infection confined to the nasal cavity. A low dose (103 plaque forming units) did not lead to detectable infectious virus shedding, but a 1000-fold higher dose led to virus shedding in all intra-nasal challenged animals. In contrast, aerosol and intra-tracheal challenge routes led to infections throughout the respiratory tract, although shedding from the nasal cavity was less reproducible between animals compared to the high-dose intra-nasal challenge group. Intra-tracheal and aerosol challenges induced a transient lymphopaenia, similar to that observed in influenza-infected humans, and greater virus-specific cellular immune responses in the blood were observed in these groups in comparison to the intra-nasal challenge groups. Activation of lung macrophages and innate immune response genes were detected at days 5 to 7 post-challenge. The kinetics of infection, both virological and immunological, were broadly in line with human influenza A virus infections. These more authentic infection models should be valuable in the determination of anti-influenza efficacy of novel entities against less severe (and thus more common) influenza infections.
Project description:The avian influenza A(H7N9) virus has caused high mortality in humans, especially in the elderly; however, little is known about the mechanistic basis for this. In this study, we employed non-human primates to evaluate the effect of aging on the pathogenicity of A(H7N9) virus. We observed that A(H7N9) virus infection of aged animals (defined as 20–26 years) caused more severe symptoms than infection of young animals (defined as 2 3 years). In aged animals, lung inflammation was weak and virus infection was sustained. Although cytokine and chemokine expression in the lungs of most aged animals was lower than that in the lungs of young animals, one aged animal showed dysregulated proinflammatory cytokine and chemokine production, resulting in it being euthanized. These results suggest that attenuated or dysregulated immune responses in aged animals are responsible for the severe symptoms observed among elderly patients infected with A(H7N9) virus.
Project description:To delineate specific patterns of signaling networks activated by H5N1 we used a comparative systems biology approach analyzing gene expression in endothelial cells infected with three different human and avian influenza strains of high and low pathogenicity. HUVECs were infected with either PR8, FPV or H5N1 virus. We used wildtype HUVEC or HUVEC transfected with a dominant negative mutant of IKK2 (block of the NF-kB signaling pathway).
Project description:Himanshu Manchanda, Nora Seidel, Andi Krumbholz, Andreas Sauerbrei, Michaela Schmidtke & Reinhard Guthke. Within-host influenza dynamics: a small-scale mathematical modeling approach. Biosystems 118 (2014).
The emergence of new influenza viruses like the pandemic H1N1 influenza A virus in 2009 (A(H1N1)pdm09) with unpredictable difficulties in vaccine coverage and established antiviral treatment protocols emphasizes the need of new murine models to prove the activity of novel antiviral compounds in vivo. The aim of the present study was to develop a small-scale mathematical model based on easily attainable experimental data to explain differences in influenza kinetics induced by different virus strains in mice. To develop a three-dimensional ordinary differential equation model of influenza dynamics, the following variables were included: (i) viral pathogenicity (P), (ii) antiviral immune defense (D), and (iii) inflammation due to pro-inflammatory response (I). Influenza virus-induced symptoms (clinical score S) in mice provided the basis for calculations of P and I. Both, mono- and biphasic course of mild to severe influenza induced by three clinical A(H1N1)pdm09 strains and one European swine H1N2 virus were comparatively and quantitatively studied by fitting the mathematical model to the experimental data. The model hypothesizes reasons for mild and severe influenza with mono- as well as biphasic course of disease. According to modeling results, the second peak of the biphasic course of infection is caused by inflammation. The parameters (i) maximum primary pathogenicity, (ii) viral infection rate, and (iii) rate of activation of the immune system represent most important parameters that quantitatively characterize the different pattern of virus-specific influenza kinetics.