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Scientifica 2024This study provides the design of a microencapsulation formula, physicochemical characterization, and antioxidant, antibacterial, and antiplasmodial activities of...
This study provides the design of a microencapsulation formula, physicochemical characterization, and antioxidant, antibacterial, and antiplasmodial activities of microcapsules. The ethanolic extract of was microencapsulated with chitosan (CHI) and sodium tripolyphosphate (Na-TPP) with various stirring times: 60 minutes (CHI60), 90 minutes (CHI90), and 120 minutes (CHI120). The microcapsules were then observed for physicochemical properties using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The microcapsules were tested for antioxidant activity and antibacterial activity against and using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Antiplasmodial bioactivity was assessed through in silico molecular docking. The CHI60 and CHI120 microcapsules exhibited a smaller size and an irregular spherical shape, while the same FTIR profile was observed in CHI90 and CHI120. The bioactivity tests demonstrated that CHI90 exhibited high antibacterial activity against and , while CHI120 exhibited high antioxidant performance. Calcigeroside B and Echinoside B exhibited antiplasmodial activity against the dihydroorotate dehydrogenase (PfDHODH) protein, along with an artemisinin inhibition mechanism. In conclusion, the microcapsules with the CHI90 formula demonstrated the best antibacterial activity, while the CHI120 formula exhibited high antioxidant activity. Two terpenoids, Calcigeroside B and Echinoside B, exhibited the best antiplasmodial activity.
PubMed: 38938546
DOI: 10.1155/2024/5559133 -
Essays in Biochemistry Jun 2024The role of malate dehydrogenase (MDH) in the metabolism of various medically significant protozoan parasites is reviewed. MDH is an NADH-dependent oxidoreductase that...
The role of malate dehydrogenase (MDH) in the metabolism of various medically significant protozoan parasites is reviewed. MDH is an NADH-dependent oxidoreductase that catalyzes interconversion between oxaloacetate and malate, provides metabolic intermediates for both catabolic and anabolic pathways, and can contribute to NAD+/NADH balance in multiple cellular compartments. MDH is present in nearly all organisms; isoforms of MDH from apicomplexans (Plasmodium falciparum, Toxoplasma gondii, Cryptosporidium spp.), trypanosomatids (Trypanosoma brucei, T. cruzi) and anaerobic protozoans (Trichomonas vaginalis, Giardia duodenalis) are presented here. Many parasitic species have complex life cycles and depend on the environment of their hosts for carbon sources and other nutrients. Metabolic plasticity is crucial to parasite transition between host environments; thus, the regulation of metabolic processes is an important area to explore for therapeutic intervention. Common themes in protozoan parasite metabolism include emphasis on glycolytic catabolism, substrate-level phosphorylation, non-traditional uses of common pathways like tricarboxylic acid cycle and adapted or reduced mitochondria-like organelles. We describe the roles of MDH isoforms in these pathways, discuss unusual structural or functional features of these isoforms relevant to activity or drug targeting, and review current studies exploring the therapeutic potential of MDH and related genes. These studies show that MDH activity has important roles in many metabolic pathways, and thus in the metabolic transitions of protozoan parasites needed for success as pathogens.
PubMed: 38938216
DOI: 10.1042/EBC20230075 -
Infection, Genetics and Evolution :... Jun 2024In malaria parasites, the erythrocyte binding-like proteins (EBL) are a family of invasion proteins that are attractive vaccine targets. In the case of Plasmodium vivax,...
In malaria parasites, the erythrocyte binding-like proteins (EBL) are a family of invasion proteins that are attractive vaccine targets. In the case of Plasmodium vivax, the widespread malaria parasite, blood-stage vaccines have been largely focused on a single EBL candidate, the Duffy binding-like domain (DBL) of the Duffy binding protein (DBPII), due to its well-characterized role in the reticulocyte invasion. A novel P. vivax EBL family member, the Erythrocyte binding protein (EBP2, also named EBP or DBP2), binds preferentially to reticulocytes and may mediate an alternative P. vivax invasion pathway. To gain insight into the natural genetic diversity of the DBL domain of EBP2 (region II; EBP2-II), we analyzed ebp2-II gene sequences of 71 P. vivax isolates collected in different endemic settings of the Brazilian Amazon rainforest, where P. vivax is the predominant malaria-associated species. Although most of the substitutions in the ebp2-II gene were non-synonymous and suggested positive selection, the results showed that the DBL domain of the EBP2 was much less polymorphic than that of DBPII. The predominant EBP2 haplotype in the Amazon region corresponded to the C127 reference sequence first described in Cambodia (25% C127-like haplotype). An overview of ebp2-II gene sequences available at GenBank (n = 352) from seven countries (Cambodia, Madagascar, Myanmar, PNG, South Korea, Thailand, Vietnam) confirmed the C127-like haplotype as highly prevalent worldwide. Two out of 43 haplotypes (5 to 20 inferred per country) showed a global frequency of 60%. The results presented here open new avenues of research pursuit while suggesting that a vaccine based on the DBL domain of EBP2 should target a few haplotypes for broad coverage.
PubMed: 38936525
DOI: 10.1016/j.meegid.2024.105628 -
International Journal For Parasitology Jun 2024Establishing an intact intracellular parasitophorous vacuole (PV) that enables efficient nutrient uptake and protein trafficking is essential for the survival and...
Establishing an intact intracellular parasitophorous vacuole (PV) that enables efficient nutrient uptake and protein trafficking is essential for the survival and proliferation of Toxoplasma gondii. Although the PV membrane (PVM)-localized dense granule protein 17 (GRA17) and GRA23 mediate the permeability of the PVM to small molecules, including nutrient uptake and excretion of metabolic by-products, the molecular mechanism by which T. gondii acquires nutrients remains unclear. In this study, we showed that the secreted protein GRA47 contributed to normal PV morphology, PVM permeability to small molecules, growth, and virulence in T. gondii. Co-immunoprecipitation analysis demonstrated potential interaction of GRA47 with GRA72, and the loss of GRA72 affected PV morphology, parasite growth and infectivity. To investigate the biological relationship among GRA47, GRA72, GRA17 and GRA23, attempts were made to construct strains with double gene deletion and overexpressing strains. Only Δgra23Δgra72 was successfully constructed. This strain exhibited a significant increase in the proportion of aberrant PVs compared with the Δgra23 strain. Overexpressing one of the three related GRAs partially rescued PVs with aberrant morphology in Δgra47, Δgra72 and Δgra17, while the expression of the Plasmodium falciparum PVM protein PfExp2, an ortholog of GRA17 and GRA23, fully rescued the PV morphological defect in all three Δgra strains. These results suggest that these three GRA proteins may not be functionally redundant but rather work in different ways to regulate nutrient acquisition. These findings highlight the versatility of the nutrient uptake mechanisms in T. gondii, which may contribute to the parasite's remarkable ability to grow in different cellular niches in a very broad range of hosts.
PubMed: 38936501
DOI: 10.1016/j.ijpara.2024.06.003 -
Journal of Medicinal Food Jun 2024Malaria impedes the ability of primary cells of the immune system to generate an efficacious inflammatory and immune response. Black seed () is a core dietary supplement...
Malaria impedes the ability of primary cells of the immune system to generate an efficacious inflammatory and immune response. Black seed () is a core dietary supplement and food additive in folklore. This study investigated the antioxidant, immunomodulatory, and anti-inflammatory effects of cookies in -infected mice. Aqueous extract of black seed was prepared, and the total phenol and flavonoid contents were determined. The mice were infected with standard inoculum of the strain NK65 . The mice weight and behavioral changes were observed. The mice were fed with the cookies (2.5%, 5%, and 10%) and 10 mg/kg chloroquine for 5 consecutive days after the infection was established. The reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase, catalase, and hematological parameters (red cell indices, leukocytes, and its differentials) in the infected mice were determined. The inflammatory mediators, C-reactive protein (CRP), and myeloperoxidase (MPO) were also assayed. The result revealed that black seed had a total phenol content of 18.73 mgGAE/g and total flavonoid content of 0.36 mgQUE/g. The infected mice treated with cookies showed significantly decreased parasitaemia, MDA, and ROS levels. Furthermore, the results showed significant suppression in proinflammatory mediators (CRP and MPO) levels and enhanced antioxidant status of infected mice treated with . The study suggests that could function as nutraceuticals in the management of infection associated with inflammatory and immunomodulatory disorders.
Topics: Animals; Plasmodium berghei; Malaria; Oxidative Stress; Mice; Nigella sativa; Seeds; Plant Extracts; Male; Antioxidants; Disease Models, Animal; Reactive Oxygen Species; Malondialdehyde; Inflammation; Anti-Inflammatory Agents; Food, Fortified; C-Reactive Protein; Superoxide Dismutase; Humans; Flavonoids; Peroxidase
PubMed: 38935918
DOI: 10.1089/jmf.2023.0181 -
PLoS Pathogens Jun 2024The cGMP-dependent protein kinase (PKG) is the sole cGMP sensor in malaria parasites, acting as an essential signalling hub to govern key developmental processes...
The cGMP-dependent protein kinase (PKG) is the sole cGMP sensor in malaria parasites, acting as an essential signalling hub to govern key developmental processes throughout the parasite life cycle. Despite the importance of PKG in the clinically relevant asexual blood stages, many aspects of malarial PKG regulation, including the importance of phosphorylation, remain poorly understood. Here we use genetic and biochemical approaches to show that reduced cGMP binding to cyclic nucleotide binding domain B does not affect in vitro kinase activity but prevents parasite egress. Similarly, we show that phosphorylation of a key threonine residue (T695) in the activation loop is dispensable for kinase activity in vitro but is essential for in vivo PKG function, with loss of T695 phosphorylation leading to aberrant phosphorylation events across the parasite proteome and changes to the substrate specificity of PKG. Our findings indicate that Plasmodium PKG is uniquely regulated to transduce signals crucial for malaria parasite development.
PubMed: 38935780
DOI: 10.1371/journal.ppat.1012360 -
PLoS Pathogens Jun 2024
Review
Topics: Malaria Vaccines; Humans; Vaccine Development; Malaria; Animals; Plasmodium falciparum; Malaria, Falciparum
PubMed: 38935630
DOI: 10.1371/journal.ppat.1012309 -
ELife Jun 2024The Zanzibar archipelago of Tanzania has become a low-transmission area for . Despite being considered an area of pre-elimination for years, achieving elimination has...
BACKGROUND
The Zanzibar archipelago of Tanzania has become a low-transmission area for . Despite being considered an area of pre-elimination for years, achieving elimination has been difficult, likely due to a combination of imported infections from mainland Tanzania and continued local transmission.
METHODS
To shed light on these sources of transmission, we applied highly multiplexed genotyping utilizing molecular inversion probes to characterize the genetic relatedness of 282 isolates collected across Zanzibar and in Bagamoyo district on the coastal mainland from 2016 to 2018.
RESULTS
Overall, parasite populations on the coastal mainland and Zanzibar archipelago remain highly related. However, parasite isolates from Zanzibar exhibit population microstructure due to the rapid decay of parasite relatedness over very short distances. This, along with highly related pairs within , suggests ongoing low-level local transmission. We also identified highly related parasites across that reflect human mobility on the main island of Unguja and identified a cluster of highly related parasites, suggestive of an outbreak, in the Micheweni district on Pemba island. Parasites in asymptomatic infections demonstrated higher complexity of infection than those in symptomatic infections, but have similar core genomes.
CONCLUSIONS
Our data support importation as a main source of genetic diversity and contribution to the parasite population in Zanzibar, but they also show local outbreak clusters where targeted interventions are essential to block local transmission. These results highlight the need for preventive measures against imported malaria and enhanced control measures in areas that remain receptive to malaria reemergence due to susceptible hosts and competent vectors.
FUNDING
This research was funded by the National Institutes of Health, grants R01AI121558, R01AI137395, R01AI155730, F30AI143172, and K24AI134990. Funding was also contributed from the Swedish Research Council, Erling-Persson Family Foundation, and the Yang Fund. RV acknowledges funding from the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 program supported by the European Union. RV also acknowledges funding by Community Jameel.
Topics: Tanzania; Plasmodium falciparum; Malaria, Falciparum; Humans; Genotype
PubMed: 38935423
DOI: 10.7554/eLife.90173 -
Antibody Therapeutics Apr 2024The recent discovery of public antibodies targeting -encoded repetitive interspersed families of polypeptides (RIFINs), which contain extracellular immunoglobulin-like... (Review)
Review
The recent discovery of public antibodies targeting -encoded repetitive interspersed families of polypeptides (RIFINs), which contain extracellular immunoglobulin-like domains from LAIR1 or LILRB1, constitutes a significant step forward in comprehending the reactivity of the parasite. These antibodies arise from unique B cell clones and demonstrate extensive cross-reactivity through their interaction with RIFINs. LAIR1 and LILRBs are specialized type I transmembrane glycoproteins, classified as immune inhibitory receptors, restricted to primates and mainly found on hematopoietic cells. They are instrumental in modulating interactions within the tumor microenvironment and across the immune system, and are increasingly recognized as important in anti-cancer immunotherapy and pathogen defense. The presence of LAIR1/LILRB1-containing antibodies offers new insights into malaria parasite evasion strategies and the immune system's response. Additionally, the innovative method of integrating extra exons into the antibody switch region is a noteworthy advancement, enriching the strategies for the generation of a varied array of bispecific and multispecific antibodies.
PubMed: 38933531
DOI: 10.1093/abt/tbae008 -
Mini Reviews in Medicinal Chemistry Jun 2024Malaria has been one of the most lethal infectious diseases throughout history, claiming a high number of human lives. The genomic plasticity of Plasmodium falciparum,...
Malaria has been one of the most lethal infectious diseases throughout history, claiming a high number of human lives. The genomic plasticity of Plasmodium falciparum, the causative agent of the most severe and deadly form of malaria, gives the parasite a constant resistance to drugs developed for its control. Despite efforts to control and even eradicate the disease, these have largely been unsuccessful due to the parasite's continuous adaptations. This study aims to examine the key genes involved in parasite resistance and propose a shift in the combat strategy. Gene silencing techniques offer promise in combating malaria, yet further research is needed to harness their potential for disease control fully. Although there is still a long way to go for the implementation of gene silencing-based therapeutic strategies, this review addresses examples of the use of such techniques in various human diseases and how they could be extrapolated for malaria treatment.
PubMed: 38932611
DOI: 10.2174/0113895575306957240610102626