Publications by authors named "Tania F de Koning-Ward"

Vaccines and diagnostic tools stand out as among the most influential advancements in public health, credited with averting an estimated 6 million deaths annually and substantially alleviating the burden of infectious disease. Despite this progress, the global imperative to prevent, detect, and combat infectious disease persists. Regrettably, hundreds of thousands of lives are still lost due to inadequate access to vaccines and diagnostics.

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Article Synopsis
  • Drug resistance is making existing antimalarials ineffective, highlighting the urgent need for new treatments.
  • Researchers identified a promising new chemotype, cyclopropyl carboxamide, through screening a library of compounds, leading to the development of a strong candidate, WJM280, which is effective against malaria without harming human cells.
  • Further studies revealed that resistant parasites have mutations in the cytochrome b gene, confirming it as the drug target, but improving the compound's stability and effectiveness in mouse models still needs to be addressed.
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The emergence of resistance against current antimalarial treatments has necessitated the need for the development of novel antimalarial chemotypes. Toward this goal, we recently optimised the antimalarial activity of the dihydroquinazolinone scaffold and showed it targeted PfATP4. Here, we deconstruct the lactam moiety of the tricyclic dihydroquinazolinone scaffold and investigate the structure-activity relationship of the truncated scaffold.

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To contribute to the global effort to develop new antimalarial therapies, we previously disclosed initial findings on the optimization of the dihydroquinazolinone-3-carboxamide class that targets PfATP4. Here we report on refining the aqueous solubility and metabolic stability to improve the pharmacokinetic profile and consequently in vivo efficacy. We show that the incorporation of heterocycle systems in the 8-position of the scaffold was found to provide the greatest attainable balance between parasite activity, aqueous solubility, and metabolic stability.

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Parasite-derived new permeation pathways (NPPs) expressed at the red blood cell (RBC) membrane enable parasites to take up nutrients from the plasma to facilitate their survival. Thus, NPPs represent a potential novel therapeutic target for malaria. The putative channel component of the NPP in the human malaria parasite is encoded by mutually exclusively expressed genes.

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Emerging resistance to current antimalarials is reducing their effectiveness and therefore there is a need to develop new antimalarial therapies. Toward this goal, high throughput screens against the P. falciparum asexual parasite identified the pyrazolopyridine 4-carboxamide scaffold.

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With resistance to most antimalarials increasing, it is imperative that new drugs are developed. We previously identified an aryl acetamide compound, MMV006833 (M-833), that inhibited the ring-stage development of newly invaded merozoites. Here, we select parasites resistant to M-833 and identify mutations in the START lipid transfer protein (PF3D7_0104200, PfSTART1).

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To combat the global burden of malaria, development of new drugs to replace or complement current therapies is urgently required. Here, we show that the compound is a selective, nanomolar inhibitor of both and aminopeptidases M1 and M17, leading to inhibition of end-stage hemoglobin digestion in asexual parasites. can kill sexual-stage , is active against murine malaria, and does not show any shift in activity against a panel of parasites resistant to other antimalarials.

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Apicomplexan parasites that reside within a parasitophorous vacuole harbor a conserved pore-forming protein that enables small-molecule transfer across the parasitophorous vacuole membrane (PVM). In parasites that cause malaria, this nutrient pore is formed by EXP2 which can complement the function of GRA17, an orthologous protein in EXP2, however, has an additional function in parasites, serving also as the pore-forming component of the protein export machinery PTEX. To examine how EXP2 can play this additional role, transgenes that encoded truncations of EXP2, GRA17, hybrid GRA17-EXP2, or EXP2 under the transcriptional control of different promoters were expressed in EXP2 knockdown parasites to determine which could complement EXP2 function.

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Cerebral malaria (CM) is a severe neurological complication caused by Plasmodium falciparum parasites; it is characterized by the sequestration of infected red blood cells within the cerebral microvasculature. New findings, combined with a better understanding of the central nervous system (CNS) barriers, have provided greater insight into the players and events involved in CM, including site-specific T cell responses in the human brain. Here, we review the updated roles of innate and adaptive immune responses in CM, with a focus on the role of the perivascular macrophage-endothelium unit in antigen presentation, in the vascular and perivascular compartments.

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The Cytokine-inducible Src homology 2 domain-containing (CISH) protein is a negative feedback regulator induced by cytokines that play key roles in immunity and erythropoiesis. Single nucleotide polymorphisms (SNPs) in the human gene have been associated with increased susceptibility to severe malaria disease. To directly assess how CISH might influence outcomes in the BALB/c model of malaria anemia, CISH knockout () mice on this background were infected with and their hematopoietic responses, cytokine production and ability to succumb to severe malaria disease evaluated.

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Article Synopsis
  • - The parasite Plasmodium falciparum, responsible for severe malaria, invades red blood cells by exporting hundreds of proteins that modify the host cell to enhance parasite growth and evade the immune system.
  • - These exported proteins contain a specific motif (PEXEL) that signals their processing and export, involving a proteolytic cleavage step in the parasite’s endoplasmic reticulum, which assists in the release of proteins into the host cell's vacuole.
  • - The study reveals that the PEXEL's sequence and a 'spacer' region between the PEXEL and functional protein regions are crucial for the protein's recognition and efficient transport by the PTEX complex into the red blood cells.
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The cytokine-inducible SH2 domain-containing (CISH) protein was the first member of the suppressor of cytokine signaling (SOCS) family of negative feedback regulators discovered, being identified in vitro as an inducible inhibitor of erythropoietin (EPO) signaling. However, understanding of the physiological role played by CISH in erythropoiesis has remained limited. To directly assess the function of CISH in this context, mice deficient in CISH were characterized with respect to developmental, steady-state, and EPO-induced erythropoiesis.

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The malaria parasite relies on variant expression of members of multi-gene families as a strategy for environmental adaptation to promote parasite survival and pathogenesis. These genes are located in transcriptionally silenced DNA regions. A limited number of these genes escape gene silencing, and switching between them confers variant fitness on parasite progeny.

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Cerebral malaria (CM) is the most severe form of malaria with the highest mortality rate and can result in life-long neurological deficits and ongoing comorbidities. Factors contributing to severity of infection and development of CM are not fully elucidated. Recent studies have indicated a key role of the gut microbiome in a range of health conditions that affect the brain, but limited microbiome research has been conducted in the context of malaria.

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the causative agent of malaria, remains a global health threat as parasites continue to develop resistance to antimalarial drugs used throughout the world. Accordingly, drugs with novel modes of action are desperately required to combat malaria. parasites infect human red blood cells where they digest the host's main protein constituent, hemoglobin.

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Most eukaryotic proteins undergo post-translational modifications (PTMs) that significantly alter protein properties, regulate diverse cellular processes and increase proteome complexity. Among these PTMs, lipidation plays a unique and key role in subcellular trafficking, signalling and membrane association of proteins through altering substrate function, and hydrophobicity via the addition and removal of lipid groups. Three prevalent classes of lipid modifications in Plasmodium parasites include prenylation, myristoylation, and palmitoylation that are important for regulating parasite-specific molecular processes.

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Infection with Plasmodium falciparum parasites results in approximately 627,000 deaths from malaria annually. Key to the parasite's success is their ability to invade and subsequently grow within human erythrocytes. Parasite proteins involved in parasite invasion and proliferation are therefore intrinsically of great interest, as targeting these proteins could provide novel means of therapeutic intervention.

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Article Synopsis
  • Plasmodium falciparum, the parasite that causes malaria, sends about 10% of its proteins into host red blood cells to alter their function using a specific sequence known as the PEXEL motif.
  • The export process involves several steps: PEXEL proteins are initially processed in the endoplasmic reticulum, then secreted into a vacuole, where they need to be unfolded and moved through a protein channel called PTEX.
  • Research shows that the proteins EXP2 and PTEX150 form a stable complex that assists another protein, HSP101, in recognizing and transporting PEXEL proteins from the parasite's ER to the vacuole, which is essential for their delivery to the host cell.
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malaria remains a global health problem as parasites continue to develop resistance to all antimalarials in use. Infection causes clinical symptoms during the intra-erythrocytic stage of the lifecycle where the parasite infects and replicates within red blood cells (RBC). During this stage, digests the main constituent of the RBC, hemoglobin, in a specialized acidic compartment termed the digestive vacuole (DV), a process essential for survival.

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To survive inside red blood cells (RBCs), malaria parasites export many proteins to alter their host cell's physiological properties. Although most proteins of this exportome are involved in immune avoidance or in the trafficking of exported proteins to the host membrane, about 20% are essential for parasite survival in culture but little is known about their biological functions. Here, we have combined information from large-scale genetic screens and targeted gene-disruption studies to tabulate all currently known Plasmodium falciparum exported proteins according to their likelihood of being essential.

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