Project description:Baris Hancioglu, David Swigon & Gilles Clermont. A dynamical model of human immune response to influenza A virus infection. Journal of Theoretical Biology 246, 1 (2007). We present a simplified dynamical model of immune response to uncomplicated influenza A virus (IAV) infection, which focuses on the control of the infection by the innate and adaptive immunity. Innate immunity is represented by interferon-induced resistance to infection of respiratory epithelial cells and by removal of infected cells by effector cells (cytotoxic T-cells and natural killer cells). Adaptive immunity is represented by virus-specific antibodies. Similar in spirit to the recent model of Bocharov and Romanyukha [1994. Mathematical model of antiviral immune response. III. Influenza A virus infection. J. Theor. Biol. 167, 323-360], the model is constructed as a system of 10 ordinary differential equations with 27 parameters characterizing the rates of various processes contributing to the course of disease. The parameters are derived from published experimental data or estimated so as to reproduce available data about the time course of IAV infection in a naïve host. We explore the effect of initial viral load on the severity and duration of the disease, construct a phase diagram that sheds insight into the dynamics of the disease, and perform sensitivity analysis on the model parameters to explore which ones influence the most the onset, duration and severity of infection. To account for the variability and speed of adaptation of the adaptive response to a particular virus strain, we introduce a variable that quantifies the antigenic compatibility between the virus and the antibodies currently produced by the organism. We find that for small initial viral load the disease progresses through an asymptomatic course, for intermediate value it takes a typical course with constant duration and severity of infection but variable onset, and for large initial viral load the disease becomes severe. This behavior is robust to a wide range of parameter values. The absence of antibody response leads to recurrence of disease and appearance of a chronic state with nontrivial constant viral load.

Project description:Background: Avian infectious bronchitis (IB) is an acute and highly contagious disease of the upper-respiratory tract caused by infectious bronchitis virus (IBV). Understanding the molecular mechanisms involved in the interaction between innate and adaptive immune responses to IBV infection is a crucial element for further improvements in strategies to control IB. To this end, two chicken lines, selected for high and low serum concentration of mannose-binding lectin (MBL), a soluble pattern recognition receptor, were studied. In total, 32 birds from each line (designated L10H for high and L10L for low MBL serum concentration, respectively) were used. Sixteen birds from each line were infected with IBV at 3 weeks of age and sixteen birds were left uninfected. Eight uninfected and eight infected birds from each line were euthanized at 1 and 3 weeks post infection. RNA sequencing was performed on spleen samples from all 64 birds used in the experiment. Differential gene expression analysis was performed for four comparisons: L10L line versus L10H line for uninfected birds at weeks 1 and 3, respectively, and L10L line versus L10H line for infected birds at weeks 1 and 3, respectively. Functional analysis based on the differentially expressed genes was performed using Gene Ontology (GO) Immune System Process terms specific for Gallus gallus. Results: Comparing uninfected L10H and L10L birds, we identified 1698 and 1424 differentially expressed (DE) genes at weeks 1 and 3, respectively. For the IBV-infected birds, 1934 and 866 DE genes were identified between the two lines at weeks 1 and 3, respectively. In both cases DE genes had FDR-adjusted p-value <0.05. The two most enriched GO terms emerging from the comparison of uninfected birds between the two lines were “Lymphocyte activation involved in immune response” (GO:0002285) and “Somatic recombination of immunoglobulin genes involved in immune response” (GO:0002204) at weeks 1 and 3, respectively. When comparing IBV-infected birds between the two lines, the most enriched GO terms were “Alpha-beta T cell activation” (GO:0046631) and “Positive regulation of leukocyte activation” (GO:0002696) at weeks 1 and 3, respectively. Conclusion: Healthy birds from the two lines showed significant differences in expression profiles for subsets of both adaptive and innate immunity-related genes, whereas comparison of the IBV-infected birds from the two lines showed differences in expression of immunity-related genes involved in T cell activation and proliferation. The observed transcriptome differences between the two lines indicate that selection for MBL had a much wider effect than solely on serum MBL concentration, and in addition influenced the innate and adaptive immune responses. Future research will focus on identifying signatures of selection in order to further understand molecular pathways be responsible for differences between the two lines as well as for efficient IBV immune protection.

Project description:Miao2010 - Innate and adaptive immune responses to primary Influenza A Virus infection This model is described in the article: Quantifying the early immune response and adaptive immune response kinetics in mice infected with influenza A virus. Miao H, Hollenbaugh JA, Zand MS, Holden-Wiltse J, Mosmann TR, Perelson AS, Wu H, Topham DJ. J. Virol. 2010 Jul; 84(13): 6687-6698 Abstract: Seasonal and pandemic influenza A virus (IAV) continues to be a public health threat. However, we lack a detailed and quantitative understanding of the immune response kinetics to IAV infection and which biological parameters most strongly influence infection outcomes. To address these issues, we use modeling approaches combined with experimental data to quantitatively investigate the innate and adaptive immune responses to primary IAV infection. Mathematical models were developed to describe the dynamic interactions between target (epithelial) cells, influenza virus, cytotoxic T lymphocytes (CTLs), and virus-specific IgG and IgM. IAV and immune kinetic parameters were estimated by fitting models to a large data set obtained from primary H3N2 IAV infection of 340 mice. Prior to a detectable virus-specific immune response (before day 5), the estimated half-life of infected epithelial cells is approximately 1.2 days, and the half-life of free infectious IAV is approximately 4 h. During the adaptive immune response (after day 5), the average half-life of infected epithelial cells is approximately 0.5 days, and the average half-life of free infectious virus is approximately 1.8 min. During the adaptive phase, model fitting confirms that CD8(+) CTLs are crucial for limiting infected cells, while virus-specific IgM regulates free IAV levels. This may imply that CD4 T cells and class-switched IgG antibodies are more relevant for generating IAV-specific memory and preventing future infection via a more rapid secondary immune response. Also, simulation studies were performed to understand the relative contributions of biological parameters to IAV clearance. This study provides a basis to better understand and predict influenza virus immunity. This model is hosted on BioModels Database and identified by: BIOMD0000000546. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Occasional transmission of highly pathogenic avian H5N1 influenza viruses to humans causes severe pneumonia with high mortality. To better understand the mechanisms via which H5N1 viruses induce severe disease in humans, we infected cynomolgus macaques with six different H5N1 strains isolated from human patients and compared their pathogenicity and the global host responses to the virus infection. Although all H5N1 viruses replicated in the respiratory tract, there was substantial heterogeneity in their replicative ability and in the disease severity induced, which ranged from asymptomatic to fatal. A comparison of global gene expression between severe and mild disease cases indicated that interferon-induced up-regulation of genes related to innate immunity, apoptosis, and antigen processing/presentation in the early phase of infection was limited in severe disease cases, although interferon expression was up-regulated in both severe and mild cases. Furthermore, co-expression analysis of microarray data, which reveals the dynamics of host responses during the infection, demonstrated that the limited expression of these genes early in infection led to a failure to suppress virus replication and to the hyperinduction of genes related to immunity, inflammation, coagulation, and homeostasis in the late phase of infection, resulting in a more severe disease. Our data suggest that the attenuated interferon-induced activation of innate immunity, apoptosis, and antigen presentation in the early phase of H5N1 virus infection leads to subsequent severe disease outcome. Bronchial brushes for microarray studies were obtained from female cynomolgus macaques infected with influenza viruses. Three animals per group were inoculated with one of three H5N1 influenza viruses (VN3028II, VN30259 or VN3040). The early phase of infection refers to timepoints Pre (prior to infection), 1, and 3 days post-infection. The late phase of infection refers to days 5 and 7 post-infection. Samples collected prior to infection (labeled as Pre) served as control data for each infection group.

Project description:Background: Pandemic H1N1 influenza A is a newly emerging strain of human influenza that is easily transmitted between people and has spread globally to over 116 countries. Human infection leads to symptoms ranging from mild to severe with lower respiratory complications observed in a small but significant number of infected individuals. Little is currently known about host immunity and Pandemic H1N1 influenza infections. Methods: We examined the pathogenic potential of the pandemic influenza A vaccine strain, A/California/07/2009 (H1N1), in ferrets, and characterized the host immune responses using microarray analysis. Gene expression profiles in lung tissue were compared with those from ferrets infected with A/Brisbane/59/2007. Results: Chemokines CCL2, CCL8, CXCL7 and CXCL10 along with the majority of ISGs were expressed early, correlated to lung pathology, and abruptly decreased expression in 5 days. Interestingly, the drop in innate immune gene expression was replaced by a significant increase in the expression of the adaptive immune genes for granzymes and immunoglobulins. Serum anti-pandemic influenza H1N1 antibodies were also observed on day 7, commensurate with the elimination of viral load. Conclusions: We propose that the innate phase of host immunity causes lung pathology and a delay or failure to effectively switch to the adaptive phase contributes to morbidity and mortality during severe human pandemic H1N1 influenza A infections. Keywords: influenza, immune response, cytokines, chemokines, lung infection, time course In the experiment with influenza A/California/07/2009 (H1N1),15 ferrets were randomly allocated to 5 groups: Day 0 (before infection), and Day 3, 5, 7 and 14 (post infection) with 3 biological replicates for each group. Likewise, a second experiment with A/Brisbane/59/2007 (H1N1) was carried out using the same experimental groups, except for a group in Day 2, instead Day 3. Ferrets were euthanized and lung tissue was excised for RNA purification on the scheduled date. The subsequent gene expression analysis was performed with Affymetrix GeneChip Canine Genome 2.0 Array. Day 0 groups were used as control.

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