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:Lassa fever is a major threat in Western Africa. The large number of people living at risk for this disease calls for the development of a vaccine against Lassa virus (LASV). We compared the efficacy of measles-based and Mopeia-based vaccine platforms against LASV in cynomolgus monkeys. The vaccines were well tolerated and protected the animals from Lassa virus infection and disease after a single immunization but with different efficacy. Analyses of immune responses demonstrated that complete protection was associated with early and robust T-cell responses against LASV but not humoral responses nor neutralizing antibodies. Transcriptomic and proteomic analyses performed during the immunization phase confirmed the role of early innate immunity and T-cell priming in vaccine efficacy and showed specific profiles detectable as early as two days after immunization. The most efficient candidate, measles vector expressing simultaneously LASV glycoprotein and nucleoprotein, will be soon evaluated in phase I clinical trial.
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: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: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. 27 RNA sampes from Human PBMC exposed to Lassa and Mop/Las (see below): 1 uninf. PBMC 4hr, 8 hr, 24 hr 2 LASV PBMC 4hr, 8 hr, 24 hr X 3 3 ML29 PBMC 4hr, 8 hr, 24 hr There are 3 biological replicates of this experiment in that the PBMC of 3 different individuals have been used.
Project description:Lassa virus is a negative-strand RNA virus with only four structural proteins that causes periodic outbreaks in West Africa. The nucleoprotein (NP) encapsidates the viral genome, forming the ribonucleoparticles together with the viral RNA and the L protein, which have to be continuously restructured during viral genome replication and transcription. Z protein is important for ribonucleoparticle recruitment, viral particle assembly and budding, and has also been shown to interact with the L protein. However, the interaction of NP, viral RNA and Z is poorly understood. Here, we characterize the interactions between Lassa virus NP, Z and RNA using structural mass spectrometry. We identify the presence of RNA as the driver for disassembly of ring-like NP trimers into monomers to subsequently form higher order assemblies. We locate the interaction site of Z and NP and demonstrate that while NP binds Z independently of the presence of RNA, this interaction is pH-dependent. These data improve our understanding of ribonucleoparticle assembly and recruitment.
Project description:A trimeric glycoprotein complex on the surface of human cytomegalovirus (CMV) binds to platelet-derived growth factor (PDGF) receptor α (PDGFRα) to mediate host cell recognition and fusion of the viral and cellular membranes. Soluble PDGFRα potently neutralizes CMV in tissue culture, and its potential use as an antiviral therapeutic has the benefit that any escape mutants will likely be attenuated. However, PDGFRα binds multiple PDGF ligands in the human body as part of developmental programs in embryogenesis and continuing through adulthood. Any therapies with soluble receptor therefore come with serious efficacy and safety concerns, especially for the treatment of congenital CMV. Soluble virus receptors that are orthogonal to human biology would reduce safety and efficacy concerns. This engineering problem is solved by deep mutational scanning on the D2-D3 domains of PDGFRα to identify variants that maintain interactions with the CMV glycoprotein trimer in the presence of competing PDGF ligands.