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Parasitology International Aug 2021Malaria parasites conceal themselves within host erythrocytes and establish a necessary logistics system through the three-membrane layered structures of these cells. To... (Review)
Review
Malaria parasites conceal themselves within host erythrocytes and establish a necessary logistics system through the three-membrane layered structures of these cells. To establish this system, lipid metabolism is needed for the de novo synthesis of lipids and the recycling of extracellular lipids and erythrocyte lipid components. Cholesterol supply depends on its uptake from the extracellular environment and erythrocyte cytoplasm, but phospholipids can be synthesized on their own. This differential production of lipid species creates unique modifications in the lipid profile of parasitized erythrocytes, which in turn may influence the biophysical and/or mechanical properties of organelles and vesicles and communication among them. Variations in local membrane properties possibly influence the transportation of various molecules such as parasite-derived proteins, because efficiencies in secretion, vesicle fusion and budding are partly determined by the lipid profiles. Comprehensive understanding of the parasite's lipid metabolism and the biophysics of lipid membranes provides fundamental knowledge about these pathogenic organisms and could lead to new anti-malarials.
Topics: Biophysical Phenomena; Host-Parasite Interactions; Lipid Metabolism; Plasmodium falciparum
PubMed: 33905815
DOI: 10.1016/j.parint.2021.102369 -
EMBO Reports Mar 2021The intra-erythrocyte stage of P. falciparum relies primarily on glycolysis to generate adenosine triphosphate (ATP) and the energy required to support growth and...
The intra-erythrocyte stage of P. falciparum relies primarily on glycolysis to generate adenosine triphosphate (ATP) and the energy required to support growth and reproduction. Lactic acid, a metabolic byproduct of glycolysis, is potentially toxic as it lowers the pH inside the parasite. Plasmodium falciparum formate-nitrite transporter (PfFNT), a 34-kDa transmembrane protein, has been identified as a novel drug target as it exports lactate from inside the parasite to the surrounding parasitophorous vacuole within the erythrocyte cytosol. The structure and detailed molecular mechanism of this membrane protein are not yet available. Here we present structures of PfFNT in the absence and presence of the functional inhibitor MMV007839 at resolutions of 2.56 Å and 2.78 Å using single-particle cryo-electron microscopy. Genetic analysis and transport assay indicate that PfFNT is able to transfer lactate across the membrane. Combined, our data suggest a stepwise displacement mechanism for substrate transport. The PfFNT membrane protein is capable of picking up lactate ions from the parasite's cytosol, converting them to lactic acids and then exporting these acids into the extracellular space.
Topics: Cryoelectron Microscopy; Formates; Nitrites; Plasmodium falciparum; Protozoan Proteins
PubMed: 33471955
DOI: 10.15252/embr.202051628 -
The American Journal of Tropical... Dec 2019In this review, we provide an epidemiological history of the emergence and ongoing spread of evolving artemisinin resistance (ARTR). Southeast Asia has been the focal... (Review)
Review
In this review, we provide an epidemiological history of the emergence and ongoing spread of evolving artemisinin resistance (ARTR). Southeast Asia has been the focal point for emergence and spread of multiple antimalarial drug resistance phenomena, and is once again for evolving ARTR, also known as the "delayed clearance phenotype" (DCP). The five countries most impacted, Cambodia, Thailand, Myanmar, Laos, and Vietnam, each have complex histories of antimalarial drug use over many decades, which have in part molded the use of various artemisinin combination therapies (ACTs) within each country. We catalog the use of ACTs, evolving loss of ACT efficacy, and the frequency of mutations (mutations associated with ARTR) in the Greater Mekong Subregion and map the historical spread of ARTR/DCP parasites. These data should assist improved surveillance and deployment of next-generation ACTs.
Topics: Artemisinins; Asia, Southeastern; Drug Resistance; Drug Therapy, Combination; Genotype; Humans; Malaria, Falciparum; Mutation; Phenotype; Plasmodium falciparum
PubMed: 31642425
DOI: 10.4269/ajtmh.19-0379 -
Journal of Medicinal Chemistry Sep 2019Malaria still affects around 200 million people and is responsible for more than 400,000 deaths per year, mostly children in subequatorial areas. This disease is caused... (Review)
Review
Malaria still affects around 200 million people and is responsible for more than 400,000 deaths per year, mostly children in subequatorial areas. This disease is caused by parasites of the genus. Only a few WHO-recommended treatments are available to prevent or cure plasmodial infections, but genetic mutations in the causal parasites have led to onset of resistance against all commercial antimalarial drugs. New drugs and targets are being investigated to cope with this emerging problem, including enzymes belonging to the main metabolic pathways, while nucleoside and nucleotide analogues are also a promising class of potential drugs. This review highlights the main metabolic pathways targeted for the development of potential antiplasmodial therapies based on nucleos(t)ide analogues, as well as the different series of purine-containing nucleoside and nucleotide derivatives designed to inhibit purine metabolism.
Topics: Antimalarials; Biological Transport; Drug Design; Erythrocytes; Humans; Inhibitory Concentration 50; Malaria; Nucleosides; Nucleotides; Plasmodium falciparum; Purines; Pyrimidines
PubMed: 30964283
DOI: 10.1021/acs.jmedchem.9b00182 -
MBio Oct 2022The repeated emergence of antimalarial drug resistance in Plasmodium falciparum, including to the current frontline antimalarial artemisinin, is a perennial problem for...
The repeated emergence of antimalarial drug resistance in Plasmodium falciparum, including to the current frontline antimalarial artemisinin, is a perennial problem for malaria control. Next-generation sequencing has greatly accelerated the identification of polymorphisms in resistance-associated genes but has also highlighted the need for more sensitive and accurate laboratory tools to profile current and future antimalarials and to quantify the impact of drug resistance acquisition on parasite fitness. The interplay of fitness and drug response is of fundamental importance in understanding why particular genetic backgrounds are better at driving the evolution of drug resistance in natural populations, but the impact of parasite fitness landscapes on the epidemiology of drug resistance has typically been laborious to accurately quantify in the lab, with assays being limited in accuracy and throughput. Here we present a scalable method to profile fitness and drug response of genetically distinct P. falciparum strains with well-described sensitivities to several antimalarials. We leverage CRISPR/Cas9 genome-editing and barcode sequencing to track unique barcodes integrated into a nonessential gene (). We validate this approach in multiplex competitive growth assays of three strains with distinct geographical origins. Furthermore, we demonstrate that this method can be a powerful approach for tracking artemisinin response as it can identify an artemisinin resistant strain within a mix of multiple parasite lines, suggesting an approach for scaling the laborious ring-stage survival assay across libraries of barcoded parasite lines. Overall, we present a novel high-throughput method for multiplexed competitive growth assays to evaluate parasite fitness and drug response. The complex interplay between antimalarial resistance and parasite fitness has important implications for understanding the development and spread of drug resistance alleles and the impact of genetic background on transmission. One limitation with current methodologies to measure parasite fitness is the ability to scale this beyond simple head-to-head competition experiments between a wildtype control line and test line, with a need for a scalable approach that allows tracking of parasite growth in complex mixtures. In our study, we have used CRISPR editing to insert unique DNA barcodes into a safe-harbor genomic locus to tag multiple parasite strains and use next-generation sequencing to read out strain dynamics. We observe inherent fitness differences between the strains, as well as sensitive modulation of responses to challenge with clinically relevant antimalarials, including artemisinin.
Topics: Antimalarials; Artemisinins; Complex Mixtures; Drug Resistance; Plasmodium falciparum; Protozoan Proteins; Genetic Fitness
PubMed: 35972144
DOI: 10.1128/mbio.00937-22 -
Biomolecules Nov 2021Malaria remains by far one of the most threatening and dangerous illnesses caused by the plasmodium falciparum parasite. Chloroquine (CQ) and first-line...
Malaria remains by far one of the most threatening and dangerous illnesses caused by the plasmodium falciparum parasite. Chloroquine (CQ) and first-line artemisinin-based combination treatment (ACT) have long been the drug of choice for the treatment and controlling of malaria; however, the emergence of CQ-resistant and artemisinin resistance parasites is now present in most areas where malaria is endemic. In this work, we developed five machine learning models to predict antimalarial bioactivities of a drug against plasmodium falciparum from the features (i.e., molecular descriptors values) obtained from PaDEL software from SMILES of compounds and compare the machine learning models by experiments with our collected data of 4794 instances. As a consequence, we found that three models amongst the five, namely artificial neural network (ANN), extreme gradient boost (XGB), and random forest (RF), outperform the others in terms of accuracy while observing that, using roughly a quarter of the promising descriptors picked by the feature selection algorithm, the five models achieved equivalent and comparable performance. Nevertheless, the contribution of all molecular descriptors in the models was investigated through the comparison of their rank values by the feature selection algorithm and found that the most potent and relevant descriptors which come from the 'Autocorrelation' module contributed more while the 'Atom type electrotopological state' contributed the least to the model.
Topics: Algorithms; Antimalarials; Databases, Pharmaceutical; Drug Evaluation, Preclinical; Machine Learning; Neural Networks, Computer; Plasmodium falciparum
PubMed: 34944394
DOI: 10.3390/biom11121750 -
MBio Jun 2021During its complex life cycle, the malaria parasite survives dramatic environmental stresses, including large temperature shifts. Protein prenylation is required during...
During its complex life cycle, the malaria parasite survives dramatic environmental stresses, including large temperature shifts. Protein prenylation is required during asexual replication of Plasmodium falciparum, and the canonical heat shock protein 40 protein (HSP40; PF3D7_1437900) is posttranslationally modified with a 15-carbon farnesyl isoprenyl group. In other organisms, farnesylation of Hsp40 orthologs controls their localization and function in resisting environmental stress. In this work, we find that plastidial isopentenyl pyrophosphate (IPP) synthesis and protein farnesylation are required for malaria parasite survival after cold and heat shock. Furthermore, loss of HSP40 farnesylation alters its membrane attachment and interaction with proteins in essential pathways in the parasite. Together, this work reveals that farnesylation is essential for parasite survival during temperature stress. Farnesylation of HSP40 may promote thermotolerance by guiding distinct chaperone-client protein interactions.
Topics: Erythrocytes; HSP40 Heat-Shock Proteins; Heat-Shock Response; Hemiterpenes; Host-Parasite Interactions; Humans; Life Cycle Stages; Organophosphorus Compounds; Plasmodium falciparum; Protein Prenylation; Protozoan Proteins; Thermotolerance
PubMed: 34182772
DOI: 10.1128/mBio.00760-21 -
Briefings in Functional Genomics Sep 2019Transcriptional differences enable the generation of alternative phenotypes from the same genome. In malaria parasites, transcriptional plasticity plays a major role in... (Review)
Review
Transcriptional differences enable the generation of alternative phenotypes from the same genome. In malaria parasites, transcriptional plasticity plays a major role in the process of adaptation to fluctuations in the environment. Multiple studies with culture-adapted parasites and field isolates are starting to unravel the different transcriptional alternatives available to Plasmodium falciparum and the underlying molecular mechanisms. Here we discuss how epigenetic variation, directed transcriptional responses and also genetic changes that affect transcript levels can all contribute to transcriptional variation and, ultimately, parasite survival. Some transcriptional changes are driven by stochastic events. These changes can occur spontaneously, resulting in heterogeneity within parasite populations that provides the grounds for adaptation by dynamic natural selection. However, transcriptional changes can also occur in response to external cues. A better understanding of the mechanisms that the parasite has evolved to alter its transcriptome may ultimately contribute to the design of strategies to combat malaria to which the parasite cannot adapt.
Topics: Adaptation, Physiological; Chromatin; Epigenesis, Genetic; Genetic Variation; Genome, Protozoan; Mutation; Phenotype; Plasmodium falciparum; Selection, Genetic; Single-Cell Analysis; Transcription, Genetic; Transcriptome
PubMed: 31114839
DOI: 10.1093/bfgp/elz009 -
Experimental Biology and Medicine... Jan 2021malaria is a global health problem. Erythrocyte invasion by merozoites appears to be a promising target to curb malaria. We have identified and characterized a novel...
malaria is a global health problem. Erythrocyte invasion by merozoites appears to be a promising target to curb malaria. We have identified and characterized a novel protein that is involved in erythrocyte invasion. Our data on protein subcellular localization, stage-specific protein expression pattern, and merozoite invasion inhibition by α-peptide antibodies suggest a role for PF3D7_1459400 protein during erythrocyte invasion. Even more, the human immunoepidemiology data present PF3D7_1459400 protein as an immunogenic antigen which could be further exploited for the development of new anti-infective therapy against malaria.
Topics: Adult; Amino Acid Sequence; Animals; Antibodies, Protozoan; Conserved Sequence; Erythrocytes; Humans; Life Cycle Stages; Plasmodium falciparum; Protozoan Proteins; Rats; Recombinant Proteins; Subcellular Fractions
PubMed: 33019810
DOI: 10.1177/1535370220961764 -
PLoS Neglected Tropical Diseases Aug 2021Understanding epidemiological variables affecting gametocyte carriage and density is essential to design interventions that most effectively reduce malaria...
BACKGROUND
Understanding epidemiological variables affecting gametocyte carriage and density is essential to design interventions that most effectively reduce malaria human-to-mosquito transmission.
METHODOLOGY/PRINCIPAL FINDINGS
Plasmodium falciparum and P. vivax parasites and gametocytes were quantified by qPCR and RT-qPCR assays using the same methodologies in 5 cross-sectional surveys involving 16,493 individuals in Brazil, Thailand, Papua New Guinea, and Solomon Islands. The proportion of infections with detectable gametocytes per survey ranged from 44-94% for P. falciparum and from 23-72% for P. vivax. Blood-stage parasite density was the most important predictor of the probability to detect gametocytes. In moderate transmission settings (prevalence by qPCR>5%), parasite density decreased with age and the majority of gametocyte carriers were children. In low transmission settings (prevalence<5%), >65% of gametocyte carriers were adults. Per survey, 37-100% of all individuals positive for gametocytes by RT-qPCR were positive by light microscopy for asexual stages or gametocytes (overall: P. falciparum 178/348, P. vivax 235/398).
CONCLUSIONS/SIGNIFICANCE
Interventions to reduce human-to-mosquito malaria transmission in moderate-high endemicity settings will have the greatest impact when children are targeted. In contrast, all age groups need to be included in control activities in low endemicity settings to achieve elimination. Detection of infections by light microscopy is a valuable tool to identify asymptomatic blood stage infections that likely contribute most to ongoing transmission at the time of sampling.
Topics: Adolescent; Asymptomatic Diseases; Brazil; Child; Child, Preschool; Cross-Sectional Studies; Female; Humans; Infant; Malaria, Falciparum; Malaria, Vivax; Male; Papua New Guinea; Plasmodium falciparum; Plasmodium vivax; Thailand; Young Adult
PubMed: 34449764
DOI: 10.1371/journal.pntd.0009672