Project description:The 2013-2016 Ebola Zaire virus (EBV) outbreak in West Africa resulted in over 28,000 cases and 11,000 deaths. Ebola virus disease (EVD) is a highly virulent systemic disease with a high case fatality rate of ~ 50%. EVD results in hemorrhagic fever marked by an exaggerated systemic inflammatory response, and impaired vascular and coagulation systems. The immune response of patients who either survived or died is characterized by strong differences. Notably, fatalities showed a diminished capacity to mount an appropriate immune response, resulting in high viremia and increased pro-inflammatory cytokine production. In this study, we analyzed 38 sequential samples collected from 12 patients: 8 survivors and 4 fatalities. Our analytical strategy combined three protein-based platforms covering three different fractions of the plasma proteome: the undepleted classical plasma proteome, the depleted plasma proteome, and cytokines/chemokines, using LC/MS- and antibody-based assays, resulting in over 1000 quantified host and pathogen proteins. For depletion of the most abundant plasma proteins, we advanced a perchloric acid-based precipitation method. This method is low cost, high-throughput and robust.
Project description:The virulent Lassa fever virus (LASV) and the non-pathogenic Mopeia virus (MOPV) infect rodents and incidentally people in West Africa. The mechanism of LASV damage in human beings is unclear. A live-attenuated reassortant of MOPV and LASV protects rodents and primates from Lassa fever disease. Peripheral blood mononuclear cells from healthy human subjects were expose to either LASV or ML29 in order to identify early cellular responses that could be attributed to the difference in virulence between both viruses. Differential expression of interferon-related genes as well as coagulation-related genes could lead to an explanation for Lassa fever pathogenesis and lead to protective treatments for Lassa fever disease.
Project description:Lassa fever outbreaks hit West African countries every year and there is still no licensed vaccine to limit the burden of this viral hemorrhagic fever. We previously developed MeV-NP, a single-shot vaccine that induces protective immunity in cynomolgus monkeys one month or more than a year before Lassa virus infection and that is able to protect against divergent viral strains. Given the limited dissemination area of Lassa virus during outbreaks and the high risk of nosocomial transmission, a vaccine that induces rapid protection could be useful to protect exposed people during outbreaks in the absence of preventive vaccination. We tested whether the time to protection could be reduced after immunization by challenging MeV pre-immune cynomolgus monkeys 16 or 8 days after a single shot of MeV-NP. None of the immunized monkeys developed disease and they rapidly controlled viral replication. Animals immunized eight days before the challenge were the best controllers, producing a strong CD8 T-cell response against the viral glycoprotein. A group of animals was also vaccinated an hour after the challenge. These animals did not develop any protective immune responses and presented the same lethal disease as the control animals. This study demonstrates that MeV-NP can induce a rapid protective immune response against Lassa fever in presence of MeV pre-existing immunity but can likely not be used as therapeutic vaccine.
Project description:Lassa fever virus (LASV) is a significant human pathogen that is endemic to several countries in West Africa. Infection with Lassa leads to the development of hemorrhagic fever in a significant number of public health cases and it is considered a potential bioweapon. Little is known about the complex immune mechanisms governing response to LASV infection, or the genetic determinants of susceptibility and resistance to infection. In the study presented here, we have used a whole-genome, microarray-based approach to determine the temporal host response to infection in the peripheral blood mononuclear cells of non-human primates (NHP) infected with LASV. Sequential sampling over the entire disease course showed that there are specific transcription signatures of the immune response to LASV infection, including the rapid up- regulation of interferon-responsive genes and toll-like receptor signaling pathways. However, this increase in early innate responses was coupled with a lack of pro- inflammatory cytokine response in LASV infected NHPs. There was a distinct lack of cytokines such as IL1b and IL23a, while immune suppressive cytokines such as IL27 and IL6 were upregulated. Comparison of cytokine gene expression with the amount of detectable protein in Lassa infected NHPs suggests that gene expression precedes the protein detection and thus is possibly a better tool for early diagnostics of the disease. Our results provide a comprehensive picture of the immune response to hemorrhagic LASV infection and provide a foundation for biomarker identification to allow clinical diagnosis of Lassa infection through analysis of the host response. RNA was isolated from a total of 46 PBMC samples from 15 cynomologus macaques infected with Lassa Virus. Samples were obtained at sequential timepoints post-infection, and included a pre-infection specimen from each animal. A subset of 30 samples (11 animals) were then processed and hybridized onto the Agilent 2-color arrays.
Project description:Zaire ebolavirus (ZEBOV) is among the deadliest known human pathogens, causing severe hemorrhagic fever with high case fatality rates ranging from 70-90%. The lack of effective vaccines or treatment available for ZEBOV renders this pathogen as a significant global biodefense threat, as evidenced by the current, highly lethal outbreak of a novel ZEBOV variant in western Africa. Existing mouse models of lethal ZEBOV infection do not reproduce hallmark symptoms of Ebola hemorrhagic fever (EHF) including prolonged blood coagulation, acute hepatitis, disseminated intravascular coagulation (DIC), and death from hemorrhagic shock, thus restricting pathogenesis studies to non-human primates (NHP). This has prevented rapid evaluation of countermeasures in outbreak scenarios, and impeded a comprehensive understanding of how host responses to infection contribute to severe EHF disease. Here we demonstrate that mice from the Collaborative Cross (CC), a panel of reproducible, recombinant inbred animals that span the genetic breadth of three murine subspecies, are susceptible to a spectrum of disease phenotypes following ZEBOV infection. In contrast to C57Bl6/J mice, which develop lethal disease without symptoms of EHF, CC recombinant inbred intercrossed (CC-RIX) lines develop either complete resistance to lethal disease or severe EHF characterized by prolonged coagulation times and 100% mortality. Disease resistance and survival is not dependent on viral tropism, as both resistant and EHF-susceptible lines show similar inflammation and cytopathic effect in target organs. Transcriptomics reveal potential mechanisms for both induction of severe hemorrhage in EHF mediated by IL-6 and vascular activation, and resistance to lethal infection by induction of lymphocyte differentiation and cellular adhesion. These data demonstrate that host responses specific to unique genetic backgrounds determine susceptibility to hemorrhagic syndrome independent of virus replication. The CC represents a novel mouse model for studying EHF pathogenesis, and we anticipate that it will be applied immediately to developing and evaluating therapeutic countermeasures. Microarrays were performed on liver and spleen samples from mice collected at days 1, 3, and 5 post-infection with mouse adapted Zaire ebolavirus or from time-matched mock-infected animals.
Project description:Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus that can cause a hemorrhagic fever in humans, with a case fatality rate of up to 50%. Cases of CCHFV have been reported in Africa, Asia, and southern Europe; and recently, due to the expanding range of its vector, autochthonous cases have been reported in Spain. Although it was discovered over 70 years ago, our understanding of the pathogenesis of this virus remains limited. We used RNA-Seq in two human liver cell lines (HepG2 and Huh7) infected with CCHFV (strain Ib 10200), to examine kinetic changes in host expression and viral replication simultaneously at 24 and 72 hours post infection. Through this, numerous host pathways were identified that were modulated by the virus including: antiviral response and endothelial cell leakage. Notably, DDX60, a cytosolic component of the RIG-I signalling pathway and OAS2 were both shown to be dysregulated. Interestingly, the PTPRR gene was induced in Huh7 cells. This has been associated with the TLR9 signalling cascade, and polymorphisms in the TLR9 gene have been associated with poor outcomes in patients. Additionally, we whole-genome sequenced CCHFV to assess viral diversity over time, and its relationship to the host response. As a result, we have demonstrated that through next-generation mRNA deep-sequencing it is possible to not only examine mRNA gene expression, but also to examine viral evolution. This demonstrates a proof-of-principle that specimens can be analyzed to identify both the virus, and host biomarkers that may have implications for prognosis.
Project description:Lassa fever virus (LASV) is a significant human pathogen that is endemic to several countries in West Africa. Infection with Lassa leads to the development of hemorrhagic fever in a significant number of public health cases and it is considered a potential bioweapon. Little is known about the complex immune mechanisms governing response to LASV infection, or the genetic determinants of susceptibility and resistance to infection. In the study presented here, we have used a whole-genome, microarray-based approach to determine the temporal host response to infection in the peripheral blood mononuclear cells of non-human primates (NHP) infected with LASV. Sequential sampling over the entire disease course showed that there are specific transcription signatures of the immune response to LASV infection, including the rapid up- regulation of interferon-responsive genes and toll-like receptor signaling pathways. However, this increase in early innate responses was coupled with a lack of pro- inflammatory cytokine response in LASV infected NHPs. There was a distinct lack of cytokines such as IL1b and IL23a, while immune suppressive cytokines such as IL27 and IL6 were upregulated. Comparison of cytokine gene expression with the amount of detectable protein in Lassa infected NHPs suggests that gene expression precedes the protein detection and thus is possibly a better tool for early diagnostics of the disease. Our results provide a comprehensive picture of the immune response to hemorrhagic LASV infection and provide a foundation for biomarker identification to allow clinical diagnosis of Lassa infection through analysis of the host response.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.