-
Methods in Molecular Biology (Clifton,... 2022The ability to interrogate gene function in Plasmodium parasites has been greatly enhanced by the advent of CRISPR/Cas9 systems. The breadth of genome manipulations... (Review)
Review
The ability to interrogate gene function in Plasmodium parasites has been greatly enhanced by the advent of CRISPR/Cas9 systems. The breadth of genome manipulations ranges from single point mutations to large multigene deletions, however many of the technical considerations for designing CRISPR-based experiments are common to any editing approach. This review will discuss protocols for vector construction and donor design for genome editing P. falciparum, including pitfalls, variables, and validation methods.
Topics: CRISPR-Cas Systems; Gene Editing; Genome, Protozoan; Plasmodium; Plasmodium falciparum
PubMed: 35881349
DOI: 10.1007/978-1-0716-2189-9_17 -
Parasitology Research Feb 2021The malaria-causing parasite Plasmodium falciparum is a severe threat to human health across the globe. This parasite alone causes the highest morbidity and mortality... (Review)
Review
The malaria-causing parasite Plasmodium falciparum is a severe threat to human health across the globe. This parasite alone causes the highest morbidity and mortality than any other species of Plasmodium. The parasites dynamically multiply in the erythrocytes of the vertebrate hosts, a large number of reactive oxygen species that damage biological macromolecules are produced in the cell during parasite growth. To relieve this intense oxidative stress, the parasite employs an NADPH-dependent thioredoxin and glutathione system that acts as an antioxidant and maintains redox status in the parasite. The mutual interaction of both redox proteins is involved in various biological functions and the survival of the erythrocytic stage of the parasite. Since the Plasmodium species is deficient in catalase and classical glutathione peroxidase, so their redox balance relies on a complex set of five peroxiredoxins, differentially positioned in the cytosol, mitochondria, apicoplast, and nucleus with partly overlapping substrate preferences. Moreover, Plasmodium falciparum possesses a set of members belonging to the thioredoxin superfamily, such as three thioredoxins, two thioredoxin-like proteins, one dithiol, three monocysteine glutaredoxins, and one redox-active plasmoredoxin with largely redundant functions. This review paper aims to discuss and encapsulate the biological function and current knowledge of the functional redox network of Plasmodium falciparum.
Topics: Animals; Antioxidants; Erythrocytes; Humans; Malaria, Falciparum; Oxidation-Reduction; Oxidative Stress; Peroxiredoxins; Plasmodium falciparum; Protozoan Proteins; Reactive Oxygen Species; Thioredoxins
PubMed: 33459846
DOI: 10.1007/s00436-021-07051-9 -
Trends in Parasitology Feb 2020The major growth in point-of-care malaria diagnosis over the past decade has been based on immunochromatographic malaria rapid diagnostic tests (mRDTs), which generally... (Review)
Review
The major growth in point-of-care malaria diagnosis over the past decade has been based on immunochromatographic malaria rapid diagnostic tests (mRDTs), which generally detect Plasmodium falciparum via its abundant histidine-rich protein 2 (HRP2). Here, we review the discovery and biology of HRP2, as well as the strengths and weaknesses of HRP2-based diagnosis compared with alternative antigens. We highlight recent studies describing HRP2 deletion in Latin America, Eritrea, and possibly other regions, and the methodological challenges of confirming deletion of the pfhrp2 gene. We also discuss the mechanism of persistent HRP2 positivity after effective antimalarial treatment, along with other emerging HRP2-based applications, including detection of submicroscopic malaria and diagnosis of severe malaria.
Topics: Antigens, Protozoan; Gene Deletion; Humans; Malaria, Falciparum; Plasmodium falciparum; Protozoan Proteins; Research
PubMed: 31848119
DOI: 10.1016/j.pt.2019.12.004 -
Nature Communications May 2023In vitro evolution of drug resistance is a powerful approach for identifying antimalarial targets, however, key obstacles to eliciting resistance are the parasite...
In vitro evolution of drug resistance is a powerful approach for identifying antimalarial targets, however, key obstacles to eliciting resistance are the parasite inoculum size and mutation rate. Here we sought to increase parasite genetic diversity to potentiate resistance selections by editing catalytic residues of Plasmodium falciparum DNA polymerase δ. Mutation accumulation assays reveal a ~5-8 fold elevation in the mutation rate, with an increase of 13-28 fold in drug-pressured lines. Upon challenge with the spiroindolone PfATP4-inhibitor KAE609, high-level resistance is obtained more rapidly and at lower inocula than wild-type parasites. Selections also yield mutants with resistance to an "irresistible" compound, MMV665794 that failed to yield resistance with other strains. We validate mutations in a previously uncharacterised gene, PF3D7_1359900, which we term quinoxaline resistance protein (QRP1), as causal for resistance to MMV665794 and a panel of quinoxaline analogues. The increased genetic repertoire available to this "mutator" parasite can be leveraged to drive P. falciparum resistome discovery.
Topics: Animals; Plasmodium falciparum; Parasites; Malaria, Falciparum; Antimalarials; Mutation; Drug Resistance; Protozoan Proteins
PubMed: 37244916
DOI: 10.1038/s41467-023-38774-1 -
Nature Communications May 2024The human infectious reservoir of Plasmodium falciparum is governed by transmission efficiency during vector-human contact and mosquito biting preferences. Understanding...
The human infectious reservoir of Plasmodium falciparum is governed by transmission efficiency during vector-human contact and mosquito biting preferences. Understanding biting bias in a natural setting can help target interventions to interrupt transmission. In a 15-month cohort in western Kenya, we detected P. falciparum in indoor-resting Anopheles and human blood samples by qPCR and matched mosquito bloodmeals to cohort participants using short-tandem repeat genotyping. Using risk factor analyses and discrete choice models, we assessed mosquito biting behavior with respect to parasite transmission. Biting was highly unequal; 20% of people received 86% of bites. Biting rates were higher on males (biting rate ratio (BRR): 1.68; CI: 1.28-2.19), children 5-15 years (BRR: 1.49; CI: 1.13-1.98), and P. falciparum-infected individuals (BRR: 1.25; CI: 1.01-1.55). In aggregate, P. falciparum-infected school-age (5-15 years) boys accounted for 50% of bites potentially leading to onward transmission and had an entomological inoculation rate 6.4x higher than any other group. Additionally, infectious mosquitoes were nearly 3x more likely than non-infectious mosquitoes to bite P. falciparum-infected individuals (relative risk ratio 2.76, 95% CI 1.65-4.61). Thus, persistent P. falciparum transmission was characterized by disproportionate onward transmission from school-age boys and by the preference of infected mosquitoes to feed upon infected people.
Topics: Humans; Anopheles; Animals; Plasmodium falciparum; Malaria, Falciparum; Male; Adolescent; Child; Child, Preschool; Female; Kenya; Mosquito Vectors; Insect Bites and Stings; Adult; Feeding Behavior; Young Adult; Infant
PubMed: 38816383
DOI: 10.1038/s41467-024-49080-9 -
Parasitology International Apr 2021Metacytofilin (MCF) was isolated from the fungus Metarhizium sp. TA2759. Although MCF possesses anti-Toxoplasma activity, the effects of this compound against other...
Metacytofilin (MCF) was isolated from the fungus Metarhizium sp. TA2759. Although MCF possesses anti-Toxoplasma activity, the effects of this compound against other parasites are unknown. Here, we evaluated the in vitro anti-malarial activity of MCF against the 3D7 strain and the chloroquine-resistant K1 strain of Plasmodium falciparum. The half maximal inhibitory concentrations (IC) of MCF against the 3D7 and K-1 strains following culture for 48 h were 666 nM and 605 nM, respectively. Artemisinin was more potent than MCF against both strains (3D7 IC: 17.4 nM; K-1 IC: 18.3 nM), while chloroquine was ineffective against the chloroquine-resistant strain (3D7 IC: 39.1 nM; K-1 IC: 1.62 μM). MCF affected the ring stage of the parasites, resulting in their death as shown by spots within red blood cells. MCF also inhibited parasite growth following culture for 72 h (3D7 IC, 285 nM). Four optical isomers of cyclo[Leu-Phe]-diketopiperazine derivatives with modified methoxy and/or hydroxyl groups lost anti-malarial activity, suggesting that the spatial positions of the methoxy and hydroxyl groups in MCF play an important role in its anti-malarial effects. Together, these data suggest that MCF may represent a promising lead compound for treatment of drug-resistant malarial parasites.
Topics: Antimalarials; Oxazines; Plasmodium falciparum
PubMed: 33307212
DOI: 10.1016/j.parint.2020.102267 -
Annual Review of Microbiology Sep 2020Although the last two decades have seen a substantial decline in malaria incidence and mortality due to the use of insecticide-treated bed nets and artemisinin... (Review)
Review
Although the last two decades have seen a substantial decline in malaria incidence and mortality due to the use of insecticide-treated bed nets and artemisinin combination therapy, the threat of drug resistance is a constant obstacle to sustainable malaria control. Given that patients can die quickly from this disease, public health officials and doctors need to understand whether drug resistance exists in the parasite population, as well as how prevalent it is so they can make informed decisions about treatment. As testing for drug efficacy before providing treatment to malaria patients is impractical, researchers need molecular markers of resistance that can be more readily tracked in parasite populations. To this end, much work has been done to unravel the genetic underpinnings of drug resistance in . The aim of this review is to provide a broad overview of common genomic approaches that have been used to discover the alleles that drive drug response phenotypes in the most lethal human malaria parasite.
Topics: Alleles; Antiprotozoal Agents; Artemisinins; Drug Resistance; Genomics; Humans; Malaria; Phenotype; Plasmodium falciparum; Protozoan Proteins
PubMed: 32905749
DOI: 10.1146/annurev-micro-012220-064343 -
Briefings in Functional Genomics Sep 2019Plasmodium falciparum and Plasmodium vivax, the two protozoan parasite species that cause the majority of cases of human malaria, have developed resistance to nearly all... (Review)
Review
Plasmodium falciparum and Plasmodium vivax, the two protozoan parasite species that cause the majority of cases of human malaria, have developed resistance to nearly all known antimalarials. The ability of malaria parasites to develop resistance is primarily due to the high numbers of parasites in the infected person's bloodstream during the asexual blood stage of infection in conjunction with the mutability of their genomes. Identifying the genetic mutations that mediate antimalarial resistance has deepened our understanding of how the parasites evade our treatments and reveals molecular markers that can be used to track the emergence of resistance in clinical samples. In this review, we examine known genetic mutations that lead to resistance to the major classes of antimalarial medications: the 4-aminoquinolines (chloroquine, amodiaquine and piperaquine), antifolate drugs, aryl amino-alcohols (quinine, lumefantrine and mefloquine), artemisinin compounds, antibiotics (clindamycin and doxycycline) and a napthoquinone (atovaquone). We discuss how the evolution of antimalarial resistance informs strategies to design the next generation of antimalarial therapies.
Topics: Aminoquinolines; Anti-Bacterial Agents; Antimalarials; Artemisinins; Atovaquone; Drug Resistance; Drug Resistance, Multiple; Folic Acid Antagonists; Humans; Malaria; Plasmodium falciparum; Plasmodium vivax; Quinine
PubMed: 31119263
DOI: 10.1093/bfgp/elz008 -
Molecular Microbiology May 2021Malaria is one of the most life-threatening infectious diseases worldwide, caused by infection of humans with parasites of the genus Plasmodium. The complex life cycle... (Review)
Review
Malaria is one of the most life-threatening infectious diseases worldwide, caused by infection of humans with parasites of the genus Plasmodium. The complex life cycle of Plasmodium parasites is shared between two hosts, with infection of multiple cell types, and the parasite needs to adapt for survival and transmission through significantly different metabolic environments. Within the blood-stage alone, parasites encounter changing levels of key nutrients, including sugars, amino acids, and lipids, due to differences in host dietary nutrition, cellular tropism, and pathogenesis. In this review, we consider the mechanisms that the most lethal of malaria parasites, Plasmodium falciparum, uses to sense nutrient levels and elicit changes in gene expression during blood-stage infections. These changes are brought about by several metabolic intermediates and their corresponding sensor proteins. Sensing of distinct nutritional signals can drive P. falciparum to alter the key blood-stage processes of proliferation, antigenic variation, and transmission.
Topics: Animals; Gene Expression; Humans; Life Cycle Stages; Malaria, Falciparum; Nutrients; Plasmodium falciparum
PubMed: 33236377
DOI: 10.1111/mmi.14652 -
Trends in Parasitology Jun 2021Malaria remains a heavy public health and socioeconomic burden in tropical and subtropical regions. Increasing resistance against front-line treatments implies that... (Review)
Review
Malaria remains a heavy public health and socioeconomic burden in tropical and subtropical regions. Increasing resistance against front-line treatments implies that novel targets for antimalarial intervention are urgently required. Protein kinases of both the parasites and their host cells possess strong potential in this respect. We present an overview of the updated kinome of Plasmodium falciparum, the species that is the largest contributor to malaria mortality, and of current knowledge pertaining to the function of parasite-encoded protein kinases during the parasite's life cycle. Furthermore, we detail recent advances in drug initiatives targeting Plasmodium kinases and outline the potential of protein kinases in the context of the growing field of host-directed therapies, which is currently being explored as a novel way to combat parasite drug resistance.
Topics: Antimalarials; Erythrocytes; Host-Parasite Interactions; Humans; Malaria; Plasmodium falciparum; Protein Kinases; Protozoan Proteins
PubMed: 33593681
DOI: 10.1016/j.pt.2021.01.002