Project description:Comaprision of P.falciparum clinical isolates showing Uncomplicated disease with that shwoing complicated disease(Cerebral malaria) The experiment was designed to try and identify differences if any, at the genome level between P.falciparum isolates from patients with uncomplicated malaria vs. patients with complicated malaria (Cerebral malaria). The emphasis was to highlight possible amplifications/deletions in different regions of the parasite genome.
Project description:Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel events that initiate sexual development in preparation for transmission of the parasite from human to mosquito. This proof-of-concept study provides a template to capture transcriptional diversity in heterogeneous parasite populations, with major implications for our understanding of parasite biology and the ongoing malaria elimination campaign.
Project description:The dry season is a major challenge for Plasmodium falciparum parasites in many malaria endemic regions, where water availability limits mosquitoes to only part of the year. How P. falciparum bridges two transmission seasons months apart, without being cleared by the host or compromising host survival is poorly understood. Here we show that low levels of P. falciparum parasites persist in the blood of asymptomatic Malian individuals during the 5- to 6-month dry season, rarely causing symptoms and minimally affecting the host immune response. Parasites isolated during the dry season are transcriptionally distinct from those of subjects with febrile malaria in the transmission season, reflecting longer circulation within each replicative cycle, of parasitized erythrocytes without adhering to the vascular endothelium. Low parasite levels during the dry season are not due to impaired replication, but rather increased efficiency of splenic clearance of longer-circulating infected erythrocytes. We propose that P. falciparum virulence in areas of seasonal malaria transmission is regulated so that the parasite decreases its endothelial binding capacity, allowing increased splenic clearance and enabling several months of subclinical parasite persistence.
Project description:The pathogenesis of severe malaria is complex and involves several pathways that influence host inflammation and endothelial function. The human malaria parasite Plasmodium falciparum is responsible for the majority of mortality and morbidity caused by malaria infection and differs from other human malaria species in the degree of accumulation of parasite-infected red blood cells in the microvasculature, known as cytoadherence or sequestration. In P. falciparum, cytoadherence is mediated by a protein called PfEMP1 which, due to its exposure to the host immune system, undergoes antigenic variation resulting in the expression of different PfEMP1 variants on the infected erythrocyte membrane. These PfEMP1s contain various combinations of adhesive domains, which allow for the differential engagement of a repertoire of endothelial receptors on the host microvasculature, with specific receptor usage associated with severe disease. Cytoadherence results in perturbation of the micro-circulation as well as direct effects on endothelial cells promoted by receptor-mediated signalling. We used a co-culture model of cytoadherence incubating human brain microvascular endothelial cells with erythrocytes infected with two parasite lines expressing different PfEMP1s; IT4var14 (long-form; ups B) that binds strongly to human brain microvascular endothelial cells mainly via ICAM-1, and IT4var 37 (short-form; ups C) that does not bind brain endothelium but shows high levels of binding to human dermal microvascular endothelial cells via CD36. We determined the transcriptional profile of the endothelial cells following different incubation periods with infected erythrocytes, identifying different transcriptional profiles of pathways involved in the pathology of severe malaria, such as inflammation, apoptosis and barrier integrity, induced by the two PfEMP1 variants.
Project description:This experiment characterizes the localisation of H2A.Z, H3K9ac and H3K4me3 in the epigenome of the human malaria parasite, P. falciparum at 4 different stages of intraerythrocytic development.
Project description:To help malaria parasites survive unpredictable host immune responses, it is known that genes for surface proteins express stochastically in Plasmodium falciparum. Here, we demonstrate that gene expression for intracellular metabolic functions may be preordained and insensitive to specific metabolic perturbations. In a tightly-controlled, large microarray study involving over 100 hybridizations to isogenic drug-sensitive and drug-resistant parasites, the lethal antifolate WR99210 failed to over-produce RNA for the biochemically and genetically proven target dihydrofolate reductase-thymidylate synthase (DHFR-TS). Beyond the target, this transcriptional obstinacy carried over to the rest of the parasite genome, including genes for target pathways of folate and pyrimidine metabolism. Even 12 hours after commitment to death, the transcriptome remained faithful to evolutionarily entrained paths. A system-wide transcriptional disregard for metabolic perturbations in malaria parasites may contribute to selective vulnerabilities of the parasite to lethal antimetabolites. While large protective metabolic responses were not detected, DNA microarrays helped capture small, but reproducible drug-dependent perturbations within hours of drug exposure. In addition, in Plasmodium cells that had adapted to long-term drug exposure, DNA microarrays revealed new, large genome-wide transcriptional adjustments in the hard-wired transcriptional program itself. Keywords: Plasmodium falciparum treated with pyrimethamine RNA from pyrimethamine-treated parasite vs RNA from untreated control, Pyr-sensitive TM4/8.2 parasite strain, pyrimethamine concentration at IC50 and treated for 2 h, 4 h, and 8 h, microarray data were obtained from at least four hybridizations using RNA from at least two independent parasite cultures
Project description:To investigate the accumulation of non coding small RNAs we performed high throughput RNA sequencing on size selcted total RNA from malaria parasite Plasmodium falciparum
Project description:This experiment characterizes the transcriptome of the human malaria parasite, P. falciparum at 8 different stages of the intraerythrocytic cycle
Project description:To help malaria parasites survive unpredictable host immune responses, it is known that genes for surface proteins express stochastically in Plasmodium falciparum. Here, we demonstrate that gene expression for intracellular metabolic functions may be preordained and insensitive to specific metabolic perturbations. In a tightly-controlled, large microarray study involving over 100 hybridizations to isogenic drug-sensitive and drug-resistant parasites, the lethal antifolate WR99210 failed to over-produce RNA for the biochemically and genetically proven target dihydrofolate reductase-thymidylate synthase (DHFR-TS). Beyond the target, this transcriptional obstinacy carried over to the rest of the parasite genome, including genes for target pathways of folate and pyrimidine metabolism. Even 12 hours after commitment to death, the transcriptome remained faithful to evolutionarily entrained paths. A system-wide transcriptional disregard for metabolic perturbations in malaria parasites may contribute to selective vulnerabilities of the parasite to lethal antimetabolites. While large protective metabolic responses were not detected, DNA microarrays helped capture small, but reproducible drug-dependent perturbations within hours of drug exposure. In addition, in Plasmodium cells that had adapted to long-term drug exposure, DNA microarrays revealed new, large genome-wide transcriptional adjustments in the hard-wired transcriptional program itself. Keywords: Plasmodium falciparum treated with pyrimethamine RNA from pyrimethamine-treated parasite vs RNA from untreated control, Pyr-sensitive TM4/8.2 strain, pyrimethamine concentration at IC50 and treated for 0 h and 24 h, microarray data were obtained from at least four hybridizations using RNA from at lease two independent parasite cultures