Project description:In order to identify RNA binding proteins that are essential for male gametogenesis in the rodent malaria parasite P. yoelii, we conducted RNA-seq analysis to identify RBPs that are specifically expressed in male gametocytes.
Project description:The study of rodent malaria parasites has significantly advanced our understanding of malaria parasite biology and host responses to parasite infections. There are four well-characterized rodent malaria parasite species (Plasmodium yoelii, P. chabaudi, P. berghei, and P. vinckei). Each species also has multiple strains that cause different disease phenotypes. P. yoelii nigeriensis N67C and N67, two isogenic parasites, are particularly intriguing as they differ in virulence and incite different immune responses in mice. The genome of the N67 parasite has been assembled recently, but not that of N67C. This study used PacBio HiFi sequencing data to assemble the N67C genome, compared the two genomes, and performed RNA sequencing to identify polymorphisms and differentially expressed genes (DEGs). Results: The assembled N67C parasite genome consisted of 16 scaffolds and three contigs of approximately 22.5 Mb with 100% and 96.6% completeness based on well-characterized single-copy orthologs specific to the Apicomplexa phylum and the Plasmodium genus, respectively. A comparison between the annotated N67C and N67 genomes revealed 133 single nucleotide polymorphisms (SNPs) and 75 indels. Among the polymorphic sites, an S (N67) to N (N67C) amino acid substitution at position 114 (S114N) in the dihydrofolate reductase-thymidylate synthase (DHFR-TS) confers resistance to pyrimethamine in mice. Additionally, 302 differentially expressed genes (DEGs) were detected after comparing mRNA levels between the two parasites. Starting with the predicted and annotated 5,681 N67C and 5,749 N67 genes, we identified 4,641 orthogroups that included at least one gene from the four P. yoelii parasites (N67, N67C, 17X, and YM), whereas 758 orthogroups showed subspecies or strain-specific patterns. Conclusion: The identification of polymorphic sites between the N67 and N67C genomes, along with the detection of the DEGs, may provide crucial insights into the variations in parasite drug responses and disease severity between these two isogenic parasites. The functional characterization of these genetic differences and candidate genes will deepen our understanding of disease mechanisms and pave the way for developing more effective control measures against malaria.
Project description:Plasmodium yoelii is a rodent parasite commonly used as a model to study liver-stage development in host system during malaria infection. Mass spectrometry-based proteomics approaches helps in understanding the proteomic profiling of parasite and provided opportunities to explore the mechanisms controlling parasite functions. It will further help in identifying new targets for therapeutic interventions, identification of Plasmodium associated virulence in the host. It will also help in the extensive refinement of parasite genome, and understanding of Post-translational modifications (PTM) in Plasmodium yoelii biology. In the present study, we performed a proteomic shotgun analysis of the Plasmodium yoelii 17XNL strain.
Project description:Malaria is a disease with diverse symptoms depending on host immune status and pathogenicity of Plasmodium parasites. The continuous parasite growth within a host suggests mechanisms of immune evasion and/or inhibition. To identify pathways commonly inhibited by malaria infection, we infected C67BL/6 mice with four Plasmodium yoelii strains causing different disease phenotypes and 24 progeny of a genetic cross. mRNAs from mouse spleens day 1 and/or day 4 post infection (p.i.) were hybridized to a mouse microarray to identify activated or inhibited pathways, upstream regulators, and linkages to parasite genetic loci. Strong interferon responses were observed after infection with N67 strain, whereas initial inhibition and later activation of hematopoiesis pathways were found after infection with 17XNL parasite. Inhibition of pathways such as Th1 activation, dendritic cell (DC) maturation, and NFAT immune regulation were observed in mice infected with all the parasite strains day 4 p.i., suggesting universally inhibited immune pathways. Treatment of infected mice with antibodies against T cell receptors OX40 or CD28 to activate malaria-inhibited pathways enhanced host survival. Controlled activation of these pathways may provide important strategies for better disease management and for developing an effective vaccine.
Project description:Plasmodium yoelii YM asexual blood stage parasites express multiple members of the py235 gene family, part of the super-family of genes including those coding for Plasmodium vivax reticulocyte binding proteins and Plasmodium falciparum RH proteins. Dr Tony Holder's laboratory (NIMR, London) has been successful in deleting one of the RH family genes (Py01365) by transfection and insertion of the TgDHFR gene, and cloned the resulting parasite in YM background. The gene expression patterns of the mutant parasite line were compared to that of the wild type YM parasite.
Project description:An invading pathogen will trigger specific host responses, which can be explored to identify genes functioning in pathogen recognition and elimination. Here we performed trans-species expression quantitative trait locus (ts-eQTL) analysis using genotypes of the Plasmodium yoelii malaria parasite and phenotypes of mouse gene expression. We significantly (LOD score≥3.0) linked 1,054 host genes to many parasite genetic loci. Clustering genome-wide pattern of LOD scores (GPLSs), which produced results different from those of direct expression level clustering, grouped host genes functioning in related pathways together, allowing accurate functional prediction of unknown genes. As proof of principle, 14 of 15 randomly selected genes unknown, but predicted to function in type I interferon (IFN-I) responses, were experimentally verified using gene over expression, shRNA knockdown, viral infection, and/or infection of KO mice. This study demonstrates an effective strategy for studying gene function, establishes a functional gene database, and identifies regulators in IFN-I pathways.