Project description:Background: The 2009 pandemic H1N1 influenza virus emerged in swine and quickly became a major global health threat. In mouse, non-human primate, and swine infection models, the pH1N1 virus efficiently replicates in the lung and induces pro-inflammatory host responses; however, whether similar or different cellular pathways were impacted by pH1N1 virus across independent infection models remains to be further defined. To address this, we have performed a comparative transcriptomic analysis of acute host responses to a single pH1N1 influenza virus, A/California/04/2009 (CA04), in the lung of mice, macaques and swine. Results: Despite similarities in the clinical course, we observed differences in inflammatory molecules elicited, and the kinetics of their gene expression changes across all three species. The retinoid X receptor (RXR) signaling pathway controlling pro-inflammatory and metabolic processes was differentially regulated during infection in each species, though the heterodimeric RXR partner, pathway associated signaling molecules, and gene expression patterns differed in each species. Conclusions: By comparing transcriptional changes in the context of clinical and virological measures, we identified differences in the host transcriptional response to pH1N1 virus across independent models of acute infection. Antiviral resistance and the emergence of new influenza viruses have placed more focus on developing drugs that target the immune system. Underlying overt clinical disease are molecular events that suggest therapeutic targets identified in one host may not be appropriate in another. The goal of this experiment was to use global gene expression profiling to understand swine lung host responses to pandemic H1N1 influenza A/Californica/04/2009 (CA04) virus infection and compare acute host responses across independent species. Four-week-old crossbred pigs (Sus Scrofa) were inoculated intratracheally with either 10^6 TCID50/pig egg-derived 2009 pandemic influenza A/California/04/2009 virus (n = 5) or mock inoculated with non-infectious cell culture supernatant (control; n = 4). Animals were euthanized on day 7 post-infection and lung samples were used for microarray.

Project description:Background: The 2009 pandemic H1N1 influenza virus emerged in swine and quickly became a major global health threat. In mouse, non-human primate, and swine infection models, the pH1N1 virus efficiently replicates in the lung and induces pro-inflammatory host responses; however, whether similar or different cellular pathways were impacted by pH1N1 virus across independent infection models remains to be further defined. To address this, we have performed a comparative transcriptomic analysis of acute host responses to a single pH1N1 influenza virus, A/California/04/2009 (CA04), in the lung of mice, macaques and swine. Results: Despite similarities in the clinical course, we observed differences in inflammatory molecules elicited, and the kinetics of their gene expression changes across all three species. The retinoid X receptor (RXR) signaling pathway controlling pro-inflammatory and metabolic processes was differentially regulated during infection in each species, though the heterodimeric RXR partner, pathway associated signaling molecules, and gene expression patterns differed in each species. Conclusions: By comparing transcriptional changes in the context of clinical and virological measures, we identified differences in the host transcriptional response to pH1N1 virus across independent models of acute infection. Antiviral resistance and the emergence of new influenza viruses have placed more focus on developing drugs that target the immune system. Underlying overt clinical disease are molecular events that suggest therapeutic targets identified in one host may not be appropriate in another. The goal of this experiment was to use global gene expression profiling to understand mouse lung cellular responses to pandemic H1N1 influenza A/Californica/04/2009 virus infection. Six-to-eight-week-old female BALB/c mice were anesthetized and inoculated with either 50 Î¼l of phosphate-buffered saline (PBS; Mock) or with 10^6 pfu of pandemic H1N1 influenza A/California/04/2009 virus in a 50 Î¼l volume, and whole lungs were collected at days 1, 3 and 5 post-inoculation. Lung samples from 9 animals for the infection group were used for array analysis, three animals per time point. Lung samples from 8 animals for the mock group were used for array analysis, three animals for the day 1 and 3 time points and 2 animals for the day 5 time point.

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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