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Nature Reviews. Microbiology Jun 2015Robust tools for analysing gene function in Plasmodium parasites, which are the causative agents of malaria, are being developed at an accelerating rate. Two decades... (Review)
Review
Robust tools for analysing gene function in Plasmodium parasites, which are the causative agents of malaria, are being developed at an accelerating rate. Two decades after genetic technologies for use in Plasmodium spp. were first described, a range of genetic tools are now available. These include conditional systems that can regulate gene expression at the genome, transcriptional or protein level, as well as more sophisticated tools for gene editing that use piggyBac transposases, integrases, zinc-finger nucleases or the CRISPR-Cas9 system. In this Review, we discuss the molecular genetic systems that are currently available for use in Plasmodium falciparum and Plasmodium berghei, and evaluate the advantages and limitations of these tools. We examine the insights that have been gained into the function of genes that are important during the blood stages of the parasites, which may help to guide the development and improvement of drug therapies and vaccines.
Topics: Animals; Genome, Protozoan; Humans; Malaria; Molecular Biology; Plasmodium berghei; Plasmodium falciparum
PubMed: 25978707
DOI: 10.1038/nrmicro3450 -
Parasites & Vectors Aug 2023Malaria caused by Plasmodium species is a prominent public health concern worldwide, and the infection of a malarial parasite is transmitted to humans through the saliva...
BACKGROUND
Malaria caused by Plasmodium species is a prominent public health concern worldwide, and the infection of a malarial parasite is transmitted to humans through the saliva of female Anopheles mosquitoes. Plasmodium invasion is a rapid and complex process. A critical step in the blood-stage infection of malarial parasites is the adhesion of merozoites to red blood cells (RBCs), which involves interactions between parasite ligands and receptors. The present study aimed to investigate a previously uncharacterized protein, PbMAP1 (encoded by PBANKA_1425900), which facilitates Plasmodium berghei ANKA (PbANKA) merozoite attachment and invasion via the heparan sulfate receptor.
METHODS
PbMAP1 protein expression was investigated at the asexual blood stage, and its specific binding activity to both heparan sulfate and RBCs was analyzed using western blotting, immunofluorescence, and flow cytometry. Furthermore, a PbMAP1-knockout parasitic strain was established using the double-crossover method to investigate its pathogenicity in mice.
RESULTS
The PbMAP1 protein, primarily localized to the P. berghei membrane at the merozoite stage, is involved in binding to heparan sulfate-like receptor on RBC surface of during merozoite invasion. Furthermore, mice immunized with the PbMAP1 protein or passively immunized with sera from PbMAP1-immunized mice exhibited increased immunity against lethal challenge. The PbMAP1-knockout parasite exhibited reduced pathogenicity.
CONCLUSIONS
PbMAP1 is involved in the binding of P. berghei to heparan sulfate-like receptors on RBC surface during merozoite invasion.
Topics: Humans; Female; Animals; Mice; Plasmodium berghei; Merozoites; Protozoan Proteins; Erythrocytes; Carrier Proteins; Plasmodium falciparum
PubMed: 37563696
DOI: 10.1186/s13071-023-05896-w -
International Journal of Molecular... May 2022The sole currently approved malaria vaccine targets the circumsporozoite protein-the protein that densely coats the surface of sporozoites, the parasite stage deposited...
The sole currently approved malaria vaccine targets the circumsporozoite protein-the protein that densely coats the surface of sporozoites, the parasite stage deposited in the skin of the mammalian host by infected mosquitoes. However, this vaccine only confers moderate protection against clinical diseases in children, impelling a continuous search for novel candidates. In this work, we studied the importance of the membrane-associated erythrocyte binding-like protein (MAEBL) for infection by sporozoites. Using transgenic parasites and live imaging in mice, we show that the absence of MAEBL reduces hemolymph sporozoite infectivity to mice. Moreover, we found that knockout (-) sporozoites display reduced adhesion, including to cultured hepatocytes, which could contribute to the defects in multiple biological processes, such as in gliding motility, hepatocyte wounding, and invasion. The - defective phenotypes in mosquito salivary gland and liver infection were reverted by genetic complementation. Using a parasite line expressing a C-terminal myc-tagged MAEBL, we found that MAEBL levels peak in midgut and hemolymph parasites but drop after sporozoite entry into the salivary glands, where the labeling was found to be heterogeneous among sporozoites. MAEBL was found associated, not only with micronemes, but also with the surface of mature sporozoites. Overall, our data provide further insight into the role of MAEBL in sporozoite infectivity and may contribute to the design of future immune interventions.
Topics: Animals; Culicidae; Erythrocytes; Membrane Proteins; Mice; Plasmodium berghei; Protozoan Proteins; Receptors, Cell Surface; Sporozoites
PubMed: 35628522
DOI: 10.3390/ijms23105711 -
Parasitology International Dec 2022Rodent malaria parasites have been widely used in all aspects of malaria research to study parasite development within rodent and insect hosts, drug resistance, disease... (Review)
Review
Rodent malaria parasites have been widely used in all aspects of malaria research to study parasite development within rodent and insect hosts, drug resistance, disease pathogenesis, host immune response, and vaccine efficacy. Rodent malaria parasites were isolated from African thicket rats and initially characterized by scientists at the University of Edinburgh, UK, particularly by Drs. Richard Carter, David Walliker, and colleagues. Through their efforts and elegant work, many rodent malaria parasite species, subspecies, and strains are now available. Because of the ease of maintaining these parasites in laboratory mice, genetic crosses can be performed to map the parasite and host genes contributing to parasite growth and disease severity. Recombinant DNA technologies are now available to manipulate the parasite genomes and to study gene functions efficiently. In this chapter, we provide a brief history of the isolation and species identification of rodent malaria parasites. We also discuss some recent studies to further characterize the different developing stages of the parasites including parasite genomes and chromosomes. Although there are differences between rodent and human malaria parasite infections, the knowledge gained from studies of rodent malaria parasites has contributed greatly to our understanding of and the fight against human malaria.
Topics: Animals; Humans; Malaria; Mice; Parasites; Plasmodium; Plasmodium berghei; Plasmodium yoelii; Rats; Rodentia
PubMed: 35926694
DOI: 10.1016/j.parint.2022.102636 -
ChemMedChem Mar 2021Multi-stage drugs have been prioritized in antimalarial drug discovery, as targeting more than one process in the Plasmodium life cycle is likely to increase efficiency,...
Multi-stage drugs have been prioritized in antimalarial drug discovery, as targeting more than one process in the Plasmodium life cycle is likely to increase efficiency, while decreasing the chances of emergence of resistance by the parasite. Herein, we disclose two novel acridine-based families of compounds that combine the structural features of primaquine and chloroquine. Compounds prepared and studied thus far retained the in vitro activity displayed by the parent drugs against the erythrocytic stages of chloroquine-sensitive and -resistant Plasmodium falciparum strains, and against the hepatic stages of Plasmodium berghei, hence acting as dual-stage antiplasmodial hits.
Topics: Aminoacridines; Antimalarials; Dose-Response Relationship, Drug; Molecular Structure; Parasitic Sensitivity Tests; Plasmodium berghei; Plasmodium falciparum; Structure-Activity Relationship
PubMed: 33217195
DOI: 10.1002/cmdc.202000740 -
Chinese Journal of Integrative Medicine Apr 2020To study the antimalarial effects and mechanisms of artemisinin (Qinghaosu in Chinese, QHS) on mitochondria in mice infected with Plasmodium berghei.
OBJECTIVE
To study the antimalarial effects and mechanisms of artemisinin (Qinghaosu in Chinese, QHS) on mitochondria in mice infected with Plasmodium berghei.
METHODS
A total of 108 C57 mice infected with Plasmodium berghei were randomly divided into 3 groups by weight: the control group, 200 and 400 mg/kg QHS groups. The two QHS treatment groups were further divided into 4 sub-groups with 12 animals each time according to the treatment time, 0.5, 1, 2, and 4 h. Normal saline was intragastrically (i.g.) administered to the control group. The other two groups received different doses of QHS by i.g. administration. Animals were treated once with QHS for different detection time as follows: 0.5, 1, 2, and 4 h. The mitochondrial energy metabolism, oxidative damage, membrane potential, and membrane permeability and other indexes were detected.
RESULTS
After administration of 200 and 400 mg/kg QHS, adenosine triphosphate (ATP) levels in Plasmodium and its mitochondria were reduced (P<0.05), the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) were increased (P<0.05), and the activity of superoxide dismutase (SOD) was also increased (P<0.05). At the same time, the membrane potential of the mitochondria was reduced and the degree to which the membrane permeability transition pore was opened was irreversibly increased (P<0.05).
CONCLUSIONS
Mitochondria in Plasmodium were the targets of QHS, which can adversely affect mitochondrial energy metabolism, oxidative damage, membrane potential, and membrane opening, and ultimately exert an antimalarial effect.
Topics: Animals; Antimalarials; Artemisinins; Energy Metabolism; Malaria, Falciparum; Membrane Potentials; Mice; Mitochondria; Oxidative Stress; Plasmodium berghei; Reactive Oxygen Species; Superoxide Dismutase
PubMed: 31227963
DOI: 10.1007/s11655-019-3164-x -
EMBO Reports Jul 2023Eukaryotic cell adhesion and migration rely on surface adhesins connecting extracellular ligands to the intracellular actin cytoskeleton. Plasmodium sporozoites are...
Eukaryotic cell adhesion and migration rely on surface adhesins connecting extracellular ligands to the intracellular actin cytoskeleton. Plasmodium sporozoites are transmitted by mosquitoes and rely on adhesion and gliding motility to colonize the salivary glands and to reach the liver after transmission. During gliding, the essential sporozoite adhesin TRAP engages actin filaments in the cytoplasm of the parasite, while binding ligands on the substrate through its inserted (I) domain. Crystal structures of TRAP from different Plasmodium species reveal the I domain in closed and open conformations. Here, we probe the importance of these two conformational states by generating parasites expressing versions of TRAP with the I domain stabilized in either the open or closed state with disulfide bonds. Strikingly, both mutations impact sporozoite gliding, mosquito salivary gland entry, and transmission. Absence of gliding in sporozoites expressing the open TRAP I domain can be partially rescued by adding a reducing agent. This suggests that dynamic conformational change is required for ligand binding, gliding motility, and organ invasion and hence sporozoite transmission from mosquito to mammal.
Topics: Animals; Sporozoites; Ligands; Plasmodium; Culicidae; Liver; Protozoan Proteins; Plasmodium berghei; Mammals
PubMed: 37306042
DOI: 10.15252/embr.202357064 -
Proceedings of the National Academy of... Oct 2023Malaria remains a devastating disease and, with current measures failing to control its transmission, there is a need for novel interventions. A family of proteins that...
Malaria remains a devastating disease and, with current measures failing to control its transmission, there is a need for novel interventions. A family of proteins that have long been pursued as potential intervention targets are aquaporins, which are channels facilitating the movement of water and other solutes across membranes. We identify an aquaporin in malaria parasites and demonstrate that it is important for completion of development in the mosquito vector. Disruption of AQP2 in the human parasite and the rodent parasite blocks sporozoite production inside oocysts established on mosquito midguts, greatly limiting parasite infection of salivary glands and transmission to a new host. In vivo epitope tagging of AQP2 in , combined with immunofluorescence assays, reveals that the protein is localized in vesicle-like organelles found in the cytoplasm of gametocytes, ookinetes, and sporozoites. The number of these organelles varies between individual parasites and lifecycle stages suggesting that they are likely part of a dynamic endomembrane system. Phylogenetic analysis confirms that AQP2 is unique to malaria and closely related parasites and most closely resembles intracellular aquaporins. Structure prediction analyses identify several unusual features, including a large accessory extracellular loop and an arginine-to-phenylalanine substitution in the selectivity filter principally determining pore function, a unique feature among known aquaporins. This in conjunction with the importance of AQP2 for malaria transmission suggests that AQP2 may be a fruitful target of antimalarial interventions.
Topics: Animals; Aquaporin 2; Malaria; Mosquito Vectors; Phylogeny; Plasmodium berghei; Protozoan Proteins; Sporozoites
PubMed: 37883438
DOI: 10.1073/pnas.2304339120 -
Frontiers in Cellular and Infection... 2022Malaria-associated acute respiratory distress syndrome (MA-ARDS) is increasingly gaining recognition as a severe malaria complication because of poor prognostic... (Review)
Review
Malaria-associated acute respiratory distress syndrome (MA-ARDS) is increasingly gaining recognition as a severe malaria complication because of poor prognostic outcomes, high lethality rate, and limited therapeutic interventions. Unfortunately, invasive clinical studies are challenging to conduct and yields insufficient mechanistic insights. These limitations have led to the development of suitable MA-ARDS experimental mouse models. In patients and mice, MA-ARDS is characterized by edematous lung, along with marked infiltration of inflammatory cells and damage of the alveolar-capillary barriers. Although, the pathogenic pathways have yet to be fully understood, the use of different experimental mouse models is fundamental in the identification of mediators of pulmonary vascular damage. In this review, we discuss the current knowledge on endothelial activation, leukocyte recruitment, leukocyte induced-endothelial dysfunction, and other important findings, to better understand the pathogenesis pathways leading to endothelial pulmonary barrier lesions and increased vascular permeability. We also discuss how the advances in imaging techniques can contribute to a better understanding of the lung lesions induced during MA-ARDS, and how it could aid to monitor MA-ARDS severity.
Topics: Animals; Disease Models, Animal; Humans; Lung; Malaria; Mice; Mice, Inbred C57BL; Plasmodium berghei; Respiratory Distress Syndrome
PubMed: 35677654
DOI: 10.3389/fcimb.2022.899581 -
The FEBS Journal Jan 2021The Apicomplexa phylum groups important human and animal pathogens that cause severe diseases, encompassing malaria, toxoplasmosis, and cryptosporidiosis. In common with... (Review)
Review
The Apicomplexa phylum groups important human and animal pathogens that cause severe diseases, encompassing malaria, toxoplasmosis, and cryptosporidiosis. In common with most organisms, apicomplexans rely on heme as cofactor for several enzymes, including cytochromes of the electron transport chain. This heme derives from de novo synthesis and/or the development of uptake mechanisms to scavenge heme from their host. Recent studies have revealed that heme synthesis is essential for Toxoplasma gondii tachyzoites, as well as for the mosquito and liver stages of Plasmodium spp. In contrast, the erythrocytic stages of the malaria parasites rely on scavenging heme from the host red blood cell. The unusual heme synthesis pathway in Apicomplexa spans three cellular compartments and comprises enzymes of distinct ancestral origin, providing promising drug targets. Remarkably given the requirement for heme, T. gondii can tolerate the loss of several heme synthesis enzymes at a high fitness cost, while the ferrochelatase is essential for survival. These findings indicate that T. gondii is capable of salvaging heme precursors from its host. Furthermore, heme is implicated in the activation of the key antimalarial drug artemisinin. Recent findings established that a reduction in heme availability corresponds to decreased sensitivity to artemisinin in T. gondii and Plasmodium falciparum, providing insights into the possible development of combination therapies to tackle apicomplexan parasites. This review describes the microeconomics of heme in Apicomplexa, from supply, either from de novo synthesis or scavenging, to demand by metabolic pathways, including the electron transport chain.
Topics: Animals; Anti-Infective Agents; Artemisinins; Cryptosporidium; Cytochromes; Erythrocytes; Ferrochelatase; Gene Expression; Heme; Host-Pathogen Interactions; Humans; Life Cycle Stages; Metabolic Networks and Pathways; Plasmodium berghei; Plasmodium falciparum; Protozoan Proteins; Toxoplasma
PubMed: 32530125
DOI: 10.1111/febs.15445