Project description:While pandemic 2009 H1N1 influenza A viruses were responsible for numerous severe infections in humans, these viruses do not typically cause corresponding severe disease in mammalian models. However, the generation of a virulent 2009 H1N1 virus following serial lung passage in mice has allowed for the modeling of human lung pathology in this species. Genetic determinants of mouse-adapted 2009 H1N1 viral pathogenicity have been identified, but the molecular and signaling characteristics of the host response following infection with this adapted virus have not been described. Here, we compared the gene-expression response following infection of mice with A/CA/04/2009 (CA/04) or the virulent mouse-adapted strain (MA-CA/04). Microarray analysis revealed that increased pathogenicity of MA-CA/04 was associated with: (1) early and sustained inflammatory and interferon response that could be driven in part by interferon regulatory factors (IRFs) and increased NFM-oM-^AM-+B activation, as well as inhibition of the negative regulator TRIM24, (2) early and persistent infiltration of immune cells, including inflammatory macrophages, and (3) the absence of activation of lipid metabolism later in infection, that may be mediated by nuclear receptors inhibition, including PPARG, HNF1A and 4A, with pro-inflammatory consequences. Further investigation of these signatures in the host response to other H1N1 viruses of varied pathogenicity confirmed their general relevance for virulence of influenza virus and suggested that lung response to MA-CA/04 virus was similar to that following lethal H1N1 r1918 influenza virus. This study links for the first time differential activation of IRFs, nuclear receptors, and macrophage infiltration with influenza virulence in vivo. Six-to-eight-week-old female BALB/c mice were anesthetized and inoculated with 50 M-NM-<l of phosphate-buffered saline (PBS; Mock) or with 10^6 pfu of virus in a 50 M-NM-<l volume. Nine animals per condition group were used for tarray analysis, two or three animals per time point. There were seven condition groups: A/California/04/2009, MA1-A/California/04/2009, A/Mexico/4482/09, A/Brisbane/59/07, A/New Jersey/8/76, the reconstructed 1918 virus and timeM-bM-^@M-^Smatched mocks.

Project description:Annually, influenza A viruses circulate the world causing wide-spread sickness, economic loss, and death. One way to better defend against influenza virus-induced disease may be to develop novel host-based therapies, targeted at mitigating viral pathogenesis through the management of virus-dysregulated host functions. However, mechanisms that govern aberrant host responses to influenza virus infection remain incompletely understood. We previously showed that the pandemic H1N1 virus influenza A/California/04/2009 (H1N1; CA04) has enhanced pathogenicity in the lungs of cynomolgus macaques relative to a seasonal influenza virus isolate (A/Kawasaki/UTK-4/2009 (H1N1; KUTK4)). Here, we used microarrays to identify host gene sequences that were highly differentially expressed (DE) in CA04-infected macaque lungs, and we employed a novel strategy M-bM-^@M-^S combining functional and pathway enrichment analyses, transcription factor binding site enrichment analysis and protein-protein interaction data M-bM-^@M-^S to create a CA04 differentially regulated host response network. This network describes enhanced viral RNA sensing, immune cell signaling and cell cycle arrest in CA04-infected lungs, and highlights a novel, putative role for the MYC-associated zinc finger (MAZ) transcription factor in regulating these processes. Lung tissues used for microarray studies were obtained from 13 female cynomolgus macaques infected with influenza viruses. 6 animals were inoculated with influenza A/California/04/2009 and 6 animals were inoculated with influenza A/Kawasaki/UTK-4/2009. 1 uninfected animal served as a negative control. On days 3 and 7 post-infection (p.i.), lung tissues were harvested from the middle and lower lung lobes of 3animals in each infection group (N = 26 total samples were collected, 3 samples were removed from the study due to low RNA quality). All but 3 samples were collected from visually apparent virus-induced gross lesions. Two lung tissue samples were obtained from middle and lower lobes of the uninfected animal at the start of the experiment.

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Homo sapiens

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