Background: R21 is a novel malaria vaccine, composed of a fusion protein of the malaria circumsporozoite protein and hepatitis B surface antigen. Following favourable safety and immunogenicity in a phase 1 study, we aimed to assess the efficacy of R21 administered with Matrix-M (R21/MM) against clinical malaria in adults from the UK who were malaria naive in a controlled human malaria infection study.
Methods: In this open-label, partially blinded, phase 1-2A controlled human malaria infection study undertaken in Oxford, Southampton, and London, UK, we tested five novel vaccination regimens of R21/MM.
Well-tolerated and novel antimalarials that can combat multiple stages of the parasite life cycle are desirable but challenging to discover and develop. Herein, we report results for natural product-inspired novel tambjamine antimalarials. We show that they are potent against liver, asexual erythrocytic, and sexual erythrocytic parasite life cycle stages.
View Article and Find Full Text PDFSevere malaria is a life-threatening condition that is associated with a high mortality. Severe infections are mediated primarily by high parasitemia and binding of infected red blood cells (iRBCs) to the blood vessel endothelial layer, a process known as sequestration. Here, we show that including the 5-amino-2-methoxybenzenesulfonate (AMBS) chemical modification in soluble biopolymers (polyglutamic acid and heparin) and poly(acrylic acid)-exposing nanoparticles serves as a universal tool to introduce a potent parasite invasion inhibitory function in these materials.
View Article and Find Full Text PDFThe pathogenesis of severe malaria involves cytoadhesive microvascular sequestration of infected erythrocytes, mediated by erythrocyte membrane protein 1 (PfEMP1). PfEMP1 variants are encoded by the highly polymorphic family of genes, the sequences of which are largely unknown in clinical samples. Previously, we published new approaches for gene profiling and classification of predicted binding phenotypes in clinical isolates (Wichers et al.
View Article and Find Full Text PDFA critical part of the malaria parasite's life cycle is invasion of red blood cells (RBCs) by merozoites. Inside RBCs, the parasite forms a schizont, which undergoes segmentation to produce daughter merozoites. These cells are released, establishing cycles of invasion.
View Article and Find Full Text PDFMalaria results in more than 500,000 deaths per year and the causative Plasmodium parasites continue to develop resistance to all known agents, including different antimalarial combinations. The class XIV myosin motor PfMyoA is part of a core macromolecular complex called the glideosome, essential for Plasmodium parasite mobility and therefore an attractive drug target. Here, we characterize the interaction of a small molecule (KNX-002) with PfMyoA.
View Article and Find Full Text PDFFlagella are important for eukaryote cell motility, including in sperm, and are vital for life cycle progression of many unicellular eukaryotic pathogens. The '9+2' axoneme in most motile flagella comprises nine outer doublet and two central-pair singlet microtubules. T-shaped radial spokes protrude from the outer doublets towards the central pair and are necessary for effective beating.
View Article and Find Full Text PDFNucleic acid extraction (NAE) plays a crucial role for diagnostic testing procedures. For decades, dried blood spots (DBS) have been used for serology, drug monitoring, and molecular studies. However, extracting nucleic acids from DBS remains a significant challenge, especially when attempting to implement these applications to the point-of-care (POC).
View Article and Find Full Text PDFHuman malaria is a life-threatening parasitic disease with high impact in the sub-Saharan Africa region, where 95% of global cases occurred in 2021. While most malaria diagnostic tools are focused on Plasmodium falciparum, there is a current lack of testing non-P. falciparum cases, which may be underreported and, if undiagnosed or untreated, may lead to severe consequences.
View Article and Find Full Text PDFMalaria remains a huge burden on global public health. Annually there are more than 200 million cases with > 600,000 deaths worldwide, the vast majority of which occur within Sub-Saharan Africa (WHO; World Malaria Report, 2021). Malaria disease is the consequence of infection by a protozoan parasite from the genus Plasmodium with most morbidity and mortality caused by P.
View Article and Find Full Text PDFThe development of new antimalarials is required because of the threat of resistance to current antimalarial therapies. To discover new antimalarial chemotypes, we screened the Janssen Jumpstarter library against the asexual parasite and identified the 7--substituted-3-oxadiazole quinolone hit class. We established the structure-activity relationship and optimized the antimalarial potency.
View Article and Find Full Text PDFThere is an urgent need to populate the antimalarial clinical portfolio with new candidates because of resistance against frontline antimalarials. To discover new antimalarial chemotypes, we performed a high-throughput screen of the Janssen Jumpstarter library against the asexual blood-stage parasite and identified the 2,3-dihydroquinazolinone-3-carboxamide scaffold. We defined the SAR and found that 8-substitution on the tricyclic ring system and 3-substitution of the exocyclic arene produced analogues with potent activity against asexual parasites equivalent to clinically used antimalarials.
View Article and Find Full Text PDFCurrent malaria treatments are threatened by drug resistance, and new drugs are urgently needed. In a phenotypic screen for new antimalarials, we identified ()-SW228703 (()-SW703), a tyrosine amide with asexual blood and liver stage activity and a fast-killing profile. Resistance to ()-SW703 is associated with mutations in the cyclic amine resistance locus (CARL) and acetyl CoA transporter (ACT), similarly to several other compounds that share features such as fast activity and liver-stage activity.
View Article and Find Full Text PDFPhenotypic cell-based screens are critical tools for discovering candidate drugs for development, yet identification of the cellular target and mode of action of a candidate drug is often lacking. Using an imaging-based screen, we recently discovered an N-[(4-hydroxychroman-4-yl)methyl]-sulphonamide (N-4HCS) compound, DDD01035881, that blocks male gamete formation in the malaria parasite life cycle and subsequent transmission of the parasite to the mosquito with nanomolar activity. To identify the target(s) of DDD01035881, and of the N-4HCS class of compounds more broadly, we synthesised a photoactivatable derivative, probe 2.
View Article and Find Full Text PDFThe multi-subunit chaperonin containing TCP-1 (CCT) is an essential molecular chaperone that functions in the folding of key cellular proteins. This paper reviews the interactome of the eukaryotic chaperonin CCT and its primary clients, the ubiquitous cytoskeletal proteins, actin and tubulin. CCT interacts with other nascent proteins, especially the WD40 propeller proteins, and also assists in the assembly of several protein complexes.
View Article and Find Full Text PDFAminoacyl transfer RNA (tRNA) synthetases (aaRSs) are attractive drug targets, and we present class I and II aaRSs as previously unrecognized targets for adenosine 5'-monophosphate-mimicking nucleoside sulfamates. The target enzyme catalyzes the formation of an inhibitory amino acid-sulfamate conjugate through a reaction-hijacking mechanism. We identified adenosine 5'-sulfamate as a broad-specificity compound that hijacks a range of aaRSs and ML901 as a specific reagent a specific reagent that hijacks a single aaRS in the malaria parasite , namely tyrosine RS (YRS).
View Article and Find Full Text PDFArtemisinin-based combination therapies have been crucial in driving down the global burden of malaria, the world's largest parasitic killer. However, their efficacy is now threatened by the emergence of resistance in Southeast Asia and sub-Saharan Africa. Thus, there is a pressing need to develop new antimalarials with diverse mechanisms of action.
View Article and Find Full Text PDFDrug resistance and a dire lack of transmission-blocking antimalarials hamper malaria elimination. Here, we present the pantothenamide MMV693183 as a first-in-class acetyl-CoA synthetase (AcAS) inhibitor to enter preclinical development. Our studies demonstrate attractive drug-like properties and in vivo efficacy in a humanized mouse model of Plasmodium falciparum infection.
View Article and Find Full Text PDFInfection 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.
View Article and Find Full Text PDFFormation of gametes in the malaria parasite occurs in the midgut of the mosquito and is critical to onward parasite transmission. Transformation of the male gametocyte into microgametes, called microgametogenesis, is an explosive cellular event and one of the fastest eukaryotic DNA replication events known. The transformation of one microgametocyte into eight flagellated microgametes requires reorganisation of the parasite cytoskeleton, replication of the 22.
View Article and Find Full Text PDFMicroscopic examination of blood smears remains the gold standard for laboratory inspection and diagnosis of malaria. Smear inspection is, however, time-consuming and dependent on trained microscopists with results varying in accuracy. We sought to develop an automated image analysis method to improve accuracy and standardization of smear inspection that retains capacity for expert confirmation and image archiving.
View Article and Find Full Text PDFThe proteasome is a potential antimalarial drug target. We have identified a series of amino-amide boronates that are potent and specific inhibitors of the 20S proteasome (20S) β5 active site and that exhibit fast-acting antimalarial activity. They selectively inhibit the growth of compared with a human cell line and exhibit high potency against field isolates of and They have a low propensity for development of resistance and possess liver stage and transmission-blocking activity.
View Article and Find Full Text PDFNovel bis-1,2,4-triazine compounds with potent activity against Plasmodium falciparum parasites were recently identified. The bis-1,2,4-triazines represent a unique antimalarial pharmacophore and are proposed to act by a novel but as-yet-unknown mechanism of action. This study investigated the activity of the bis-1,2,4-triazine MIPS-0004373 across the mammalian life cycle stages of the parasite and profiled the kinetics of activity against blood and transmission stage parasites and .
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