Conserved host response to highly pathogenic avian influenza virus infection in human cell culture, mouse and macaque model systems

<p>Abstract</p> <p>Background</p> <p>Understanding host response to influenza virus infection will facilitate development of better diagnoses and therapeutic interventions. Several different experimental models have been used as a proxy for human infection, including cell cultures derived from human cells, mice, and non-human primates. Each of these systems has been studied extensively in isolation, but little effort has been directed toward systematically characterizing the conservation of host response on a global level beyond known immune signaling cascades.</p> <p>Results</p> <p>In the present study, we employed a multivariate modeling approach to characterize and compare the transcriptional regulatory networks between these three model systems after infection with a highly pathogenic avian influenza virus of the H5N1 subtype. Using this approach we identified functions and pathways that display similar behavior and/or regulation including the well-studied impact on the interferon response and the inflammasome. Our results also suggest a primary response role for airway epithelial cells in initiating hypercytokinemia, which is thought to contribute to the pathogenesis of H5N1 viruses. We further demonstrate that we can use a transcriptional regulatory model from the human cell culture data to make highly accurate predictions about the behavior of important components of the innate immune system in tissues from whole organisms.</p> <p>Conclusions</p> <p>This is the first demonstration of a global regulatory network modeling conserved host response between <it>in vitro </it>and <it>in vivo </it>models.</p

Systems biology and systems genetics—novel innovative approaches to study host–pathogen interactions during influenza infection

Influenza represents a serious threat to public health with thousands of deaths each year. A deeper understanding of the host–pathogen interactions is urgently needed to evaluate individual and population risks for severe influenza disease and to identify new therapeutic targets. Here, we review recent progress in large scale omics technologies, systems genetics as well as new mathematical and computational developments that are now in place to apply a systems biology approach for a comprehensive description of the multidimensional host response to influenza infection. In addition, we describe how results from experimental animal models can be translated to humans, and we discuss some of the future challenges ahead

Developing a Model of H5N1 Influenza Pathogenesis in Precision-Cut Human Lung Slices

Highly pathogenic avian H5N1, known as HPAI H5N1, is a strain of influenza that is highly contagious in poultry and is occasionally spread to people that have had close contact with infected poultry. In humans, the fatality rate is 60%, though person-to-person transmission rarely occurs. HPAI H5N1 causes severe acute respiratory distress syndrome (ARDS), fluid buildup in the lung alveoli, making it hard for the lungs to get adequate oxygen due to a severe inflammatory response, followed by an inflammatory response and subsequent epithelial cell death in the lungs. The mechanism for ARDS is poorly understood. While models of infection exist in lab animals, a representative ex vivo model of infection in humans is needed to study the severe outcome of disease. An emerging alternative to animal models and immortalized cell culture models is precision-cut tissue slices of the organ of interest, using human donors as a source of tissue. In this study, I developed a model of H5N1-infected precision-cut lung porcine then human slices and utilized said model to elucidate the mechanism of ARDS by selectively inhibiting members of cell death pathways and observe changes in downstream cytokines. Fluorescent immunohistochemistry was used to visualize and quantify markers of cell death and infection using image quantification. Changes in IL-1B were observed by enzyme-linked immunosorbent assay (ELISA). Here, I demonstrate that pyroptotic cell death is induced in response to H5N1 infection ex vivo as demonstrated by reduced IL-1B levels in response to a caspase-1/4 inhibitor and a gasdermin-D (GSDMD) inhibitor. This approach could prove public health relevance in developing novel, host-directed therapies to treat severe influenza infection in humans by providing a model to easily test human responses

mBio

A novel avian-origin H7N9 influenza A virus (IAV) emerged in China in 2013, causing mild to lethal human respiratory infections. H7N9 originated with multiple reassortment events between avian viruses and carries genetic markers of human adaptation. Determining whether H7N9 induces a host response closer to that with human or avian IAV is important in order to better characterize this emerging virus. Here we compared the human lung epithelial cell response to infection with A/Anhui/01/13 (H7N9) or highly pathogenic avian-origin H5N1, H7N7, or human seasonal H3N2 IAV. The transcriptomic response to H7N9 was highly specific to this strain but was more similar to the response to human H3N2 than to that to other avian IAVs. H7N9 and H3N2 both elicited responses related to eicosanoid signaling and chromatin modification, whereas H7N9 specifically induced genes regulating the cell cycle and transcription. Among avian IAVs, the response to H7N9 was closest to that elicited by H5N1 virus. Host responses common to H7N9 and the other avian viruses included the lack of induction of the antigen presentation pathway and reduced proinflammatory cytokine induction compared to that with H3N2. Repression of these responses could have an important impact on the immunogenicity and virulence of H7N9 in humans. Finally, using a genome-based drug repurposing approach, we identified several drugs predicted to regulate the host response to H7N9 that may act as potential antivirals, including several kinase inhibitors, as well as FDA-approved drugs, such as troglitazone and minocycline. Importantly, we validated that minocycline inhibited H7N9 replication in vitro, suggesting that our computational approach holds promise for identifying novel antivirals.|Whether H7N9 will be the next pandemic influenza virus or will persist and sporadically infect humans from its avian reservoir, similar to H5N1, is not known yet. High-throughput profiling of the host response to infection allows rapid characterization of virus-host interactions and generates many hypotheses that will accelerate understanding and responsiveness to this potential threat. We show that the cellular response to H7N9 virus is closer to that induced by H3N2 than to that induced by H5N1, reflecting the potential of this new virus for adaptation to humans. Importantly, dissecting the host response to H7N9 may guide host-directed antiviral development.HHSN266200700008C/PHS HHS/United State

Multigenic DNA Vaccine Induces Protective Cross-Reactive T Cell Responses Against Heterologous Influenza Virus in Nonhuman Primates

Recent avian and swine-origin influenza virus outbreaks illustrate the ongoing threat of influenza pandemics. We investigated immunogenicity and protective efficacy of a multi-antigen (MA) universal influenza DNA vaccine consisting of HA, M2, and NP antigens in cynomolgus macaques. Following challenge with a heterologous pandemic H1N1 strain, vaccinated animals exhibited significantly lower viral loads and more rapid viral clearance when compared to unvaccinated controls. The MA DNA vaccine induced robust serum and mucosal antibody responses but these high antibody titers were not broadly neutralizing. In contrast, the vaccine induced broadly-reactive NP specific T cell responses that cross-reacted with the challenge virus and inversely correlated with lower viral loads and inflammation. These results demonstrate that a MA DNA vaccine that induces strong cross-reactive T cell responses can, independent of neutralizing antibody, mediate significant cross-protection in a nonhuman primate model and further supports development as an effective approach to induce broad protection against circulating and emerging influenza strains

Human H7N9 virus induces a more pronounced pro-inflammatory cytokine but an attenuated interferon response in human bronchial epithelial cells when compared with an epidemiologically-linked chicken H7N9 virus

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Cross-Reactive T Cells Are Involved in Rapid Clearance of 2009 Pandemic H1N1 Influenza Virus in Nonhuman Primates

In mouse models of influenza, T cells can confer broad protection against multiple viral subtypes when antibodies raised against a single subtype fail to do so. However, the role of T cells in protecting humans against influenza remains unclear. Here we employ a translational nonhuman primate model to show that cross-reactive T cell responses play an important role in early clearance of infection with 2009 pandemic H1N1 influenza virus (H1N1pdm). To “prime” cellular immunity, we first infected 5 rhesus macaques with a seasonal human H1N1 isolate. These animals made detectable cellular and antibody responses against the seasonal H1N1 isolate but had no neutralizing antibodies against H1N1pdm. Four months later, we challenged the 5 “primed” animals and 7 naive controls with H1N1pdm. In naive animals, CD8+ T cells with an activated phenotype (Ki-67+ CD38+) appeared in blood and lung 5–7 days post inoculation (p.i.) with H1N1pdm and reached peak magnitude 7–10 days p.i. In contrast, activated T cells were recruited to the lung as early as 2 days p.i. in “primed” animals, and reached peak frequencies in blood and lung 4–7 days p.i. Interferon (IFN)-γ Elispot and intracellular cytokine staining assays showed that the virus-specific response peaked earlier and reached a higher magnitude in “primed” animals than in naive animals. This response involved both CD4+ and CD8+ T cells. Strikingly, “primed” animals cleared H1N1pdm infection significantly earlier from the upper and lower respiratory tract than the naive animals did, and before the appearance of H1N1pdm-specific neutralizing antibodies. Together, our results suggest that cross-reactive T cell responses can mediate early clearance of an antigenically novel influenza virus in primates. Vaccines capable of inducing such cross-reactive T cells may help protect humans against severe disease caused by newly emerging pandemic influenza viruses