Project description:Cumulative malaria parasite exposure in endemic regions often results in the acquisition of partial immunity and asymptomatic infections. There is limited information on how host-parasite interactions mediate maintenance of chronic symptomless infections that sustain malaria transmission. Here, we have determined the gene expression profiles of the parasite population and the corresponding host peripheral blood mononuclear cells (PBMCs) from 21 children (<15 years). We compared children who were defined as uninfected, asymptomatic and those with febrile malaria. Children with asymptomatic infections had a parasite transcriptional profile characterized by a bias toward trophozoite stage (~12 hours-post invasion) parasites and low parasite levels, while earlier ring stage parasites were characteristic of febrile malaria. The host response of asymptomatic children was characterized by downregulated transcription of genes associated with inflammatory responses, compared with children with febrile malaria, which may lead to less cytoadherence of more mature parasite stages. Interestingly, the host responses during febrile infections that followed an asymptomatic infection featured stronger inflammatory responses, whereas the febrile host responses from previously uninfected children featured increased humoral immune responses. The priming effect of prior asymptomatic infection may explain the blunted acquisition of antibody responses seen to malaria antigens following natural exposure or vaccination in malaria endemic areas.
Project description:Rodent malaria parasite RNA hybridized on Illumina Mouse WG-6 v2.0 Expression BeadChip To investigate whether parasite RNA interfere with mouse beadchip analaysis. Malaria parasite resides in red blood cell, therefore RNA isolated from whole infected blood contains host RNA as well as parasite RNA
Project description:Cerebral Malaria (CM), the deadliest complication of Plasmodium infection, is a complex and unpredictable disease. Currently, our understanding of the factors that trigger progression of malaria to CM is limited. Here, by infecting experimental CM (ECM) resistant (Balb/c) and ECM susceptible (C57BL/6) mice with ECM causing (ANKA) and non-ECM causing (NK65) Plasmodium berghei (Pb) parasite strains, we revealed that in resistant host, infection by ECM causing parasite develops similar to infection by non-ECM causing parasite in susceptible host in terms of parasite growth in host, disease course and host immune response against parasite. Our comparative gene expression analysis revealed that in Balb/c host, gene expression of Pb ANKA parasite is remarkably different from, the gene expression of Pb ANKA in C57BL/6 but similar to the gene expression of non-ECM causing Pb NK65 in C57BL/6. Thus, host has a critical influence on parasite behavior which ultimately determines the course of malaria disease.
Project description:Malaria infection triggers vigorous host immune responses; however, the parasite ligands, host receptors and the signaling pathways responsible for these reactions remain unknown or controversial. Malaria parasites primarily reside within red blood cells (RBCs), thereby hiding themselves from direct contact and recognition by host immune cells. Host responses to malaria infection are very different from those elicited by bacterial and viral infections and the host receptors recognizing parasite ligands have been elusive. Here we investigated mouse genome-wide transcriptional responses to infections with two strains of Plasmodium yoelii (N67 and N67C) and discovered differences in innate response pathways corresponding to strain-specific disease phenotypes. Using in vitro RNAi gene knockdown and knockout mice, we demonstrated that a strong IFN-I response triggered by RNA Polymerase III and melanoma differentiation-associated protein 5 (MDA5), not Toll-like receptors (TLRs), binding of parasite DNA/RNA contributed to a decline of parasitemia in N67-infected mice. We showed that conventional dendritic cells were the major sources of early IFN-I, and that surface expression of phosphatidylserine (PS) on infected RBC (iRBC) might promote their phagocytic uptake, leading to the release of parasite ligands and the IFN-I response in N67 infection. In contrast, an elevated inflammatory response mediated by CD14/TLR and p38 signaling played a role in disease severity and early host death in N67C-infected mice. In addition to identifying cytosolic DNA/RNA sensors and signaling pathways previously unrecognized in malaria infection, our study demonstrates the importance of parasite genetic backgrounds in malaria pathology and provides important information for studying human malaria pathogenesis. Spleen RNA from mice, 4 days post infection with Plasmodium yoelii (strain N67 or N67C), or mock infection (N). Replicates from 6 individual mice per condition.
Project description:Malarial rhythmic fevers are the consequence of the synchronous bursting of red blood cells (RBCs) upon completion of the malaria parasite asexual cell-cycle. Here we hypothesized that an intrinsic clock in the parasite underlies the modulo-24h rhythms of RBC bursting. We show that parasite rhythms are plastic and slow down to match rhythms of hosts with long circadian period. We also demonstrate that malaria rhythms persist even when host food intake is evenly spread across 24h, suggesting that host feeding cues are not required for synchrony. Moreover, we find that the parasite population remains synchronous and rhythmic even in an arrhythmic clock mutant host. Thus, we propose that parasite rhythms are generated by the parasite, possibly to anticipate its rhythmic changing environment.
Project description:Malaria infection triggers vigorous host immune responses; however, the parasite ligands, host receptors and the signaling pathways responsible for these reactions remain unknown or controversial. Malaria parasites primarily reside within red blood cells (RBCs), thereby hiding themselves from direct contact and recognition by host immune cells. Host responses to malaria infection are very different from those elicited by bacterial and viral infections and the host receptors recognizing parasite ligands have been elusive. Here we investigated mouse genome-wide transcriptional responses to infections with two strains of Plasmodium yoelii (N67 and N67C) and discovered differences in innate response pathways corresponding to strain-specific disease phenotypes. Using in vitro RNAi gene knockdown and knockout mice, we demonstrated that a strong IFN-I response triggered by RNA Polymerase III and melanoma differentiation-associated protein 5 (MDA5), not Toll-like receptors (TLRs), binding of parasite DNA/RNA contributed to a decline of parasitemia in N67-infected mice. We showed that conventional dendritic cells were the major sources of early IFN-I, and that surface expression of phosphatidylserine (PS) on infected RBC (iRBC) might promote their phagocytic uptake, leading to the release of parasite ligands and the IFN-I response in N67 infection. In contrast, an elevated inflammatory response mediated by CD14/TLR and p38 signaling played a role in disease severity and early host death in N67C-infected mice. In addition to identifying cytosolic DNA/RNA sensors and signaling pathways previously unrecognized in malaria infection, our study demonstrates the importance of parasite genetic backgrounds in malaria pathology and provides important information for studying human malaria pathogenesis.
Project description:Liver stage of malaria parasite exports SLTRiP and PB268 to the cytosol of parasite infected host cell. To know the host genes perturbed by WT-PBANKA, SLTRiP-KO and PB268-KO parasite growth, we did transcriptomic sequencing of infected host cells. We did mRNA sequencing of four samples for comparative analysis of WT and PB-knockout parasites infected host cells at 22 hours of post sporozoites infection.
Project description:Liver stage of malaria parasite exports SLTRiP and PB268 to the cytosol of parasite infected host cell. To know the host genes perturbed by WT-PBANKA, SLTRiP-KO and PB268-KO parasite growth, we did transcriptomic sequencing of infected host cells. We did mRNA sequencing of four samples for comparative analysis of WT and PB-knockout parasites infected host cells at 22 hours of post sporozoites infection. mRNA profiles of Plasmodium PBANKA, PBSLTRiP-KO, PB268-KO parasite infected and uninfected HepG2 cells after 22hrs of sporozoites infections were generated by deep sequencing using Illumina GAIIx.
Project description:N6-Methyladenosine (m6A) modification has been found to play important roles in diverse pathogen infections and host responses, here we report host m6A mRNA transcriptome profiles regulated by the infections of two strains of malaria parasite Plasmodium yoelii (N67 and N67C). We showed that malaria infection can regulate host m6A mRNA modification and reprogram host m6A mRNA methylome by mediating corresponding m6A catalytic enzyme levels. Our data suggested m6A modification as a significant transcriptome-wide mark during host-malaria interactions.