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Bulletin of the World Health... Aug 2020To calculate prevalence estimates and evaluate the quality of studies reporting lacking histidine-rich proteins 2 and 3, to inform an international response plan.
OBJECTIVE
To calculate prevalence estimates and evaluate the quality of studies reporting lacking histidine-rich proteins 2 and 3, to inform an international response plan.
METHODS
We searched five online databases, without language restriction, for articles reporting original data on -infected patients with deletions of the and/or genes (). We calculated prevalence estimates of deletions and mapped the data by country. The denominator was all -positive samples testing positive by microscopy and confirmed positive by species-specific polymerase chain reaction testing (PCR). If microscopy was not performed, we used the number of samples based on a different diagnostic method or PCR alone. We scored studies for risk of bias and the quality of laboratory methods using a standardized scoring system.
FINDINGS
A total of 38 articles reporting 55 studies from 32 countries and one territory worldwide were included in the review. We found considerable heterogeneity in the populations studied, methods used and estimated prevalence of parasites with deletions. The derived prevalence of deletions ranged from 0% to 100%, including focal areas in South America and Africa. Only three studies (5%) fulfilled all seven criteria for study quality.
CONCLUSION
The lack of representative surveys or consistency in study design impairs evaluations of the risk of false-negative results in malaria diagnosis due to deletions. Accurate mapping and strengthened monitoring of the prevalence of deletions is needed, along with harmonized methods that facilitate comparisons across studies.
Topics: Antigens, Protozoan; Humans; Malaria, Falciparum; Plasmodium falciparum; Polymerase Chain Reaction; Prevalence; Proteins; Protozoan Proteins
PubMed: 32773901
DOI: 10.2471/BLT.20.250621 -
Protoplasma Jul 2020Malaria is one of the major causes of mortality as well as morbidity in many tropical and subtropical countries around the world. Although artemisinin combination...
Malaria is one of the major causes of mortality as well as morbidity in many tropical and subtropical countries around the world. Although artemisinin combination therapies (ACTs) are contributing to substantial decline in the worldwide malaria burden, it is becoming vulnerable by the emergence of artemisinin resistance in Plasmodium falciparum leading to clinical failure of ACTs in Southeast Asia. Helicases play important role in nucleic acid metabolic processes and have been also identified as therapeutic drug target for different diseases. Previously, it has been reported that P. falciparum contains a group of DEAD-box family of helicases which are homologous to Has1 family of yeast. Here, we present the characterization of a member of Has1 family (PlasmoDB number PF3D7_1419100) named as PfDDX55. The biochemical characterization of PfDDX55C revealed that it contains both DNA- and RNA-dependent ATPase activity. PfDDX55C unwinds partially duplex DNA in 3' to 5' direction and utilizes mainly ATP or dATP for its activity. The immunofluorescence assay and q-RT PCR analysis show that PfDDX55 is a nucleocytoplasmic protein expressed in all the intraerythrocytic development of P. falciparum 3D7 strain with maximum expression level in trophozoite stage. The LC-MS/MS experiment results and STRING analysis show that PfDDX55 interacts with AAA-ATPase which has been shown to be involved in ribosomal biogenesis.
Topics: Animals; Anopheles; DNA Helicases; Humans; Mice; Plasmodium falciparum; Rabbits
PubMed: 32125511
DOI: 10.1007/s00709-020-01495-z -
Journal of Biomolecular Structure &... May 2022Prefoldin (PFD) is a heterohexameric molecular chaperone which bind unfolded proteins and subsequently deliver them to a group II chaperonin for correct folding.... (Comparative Study)
Comparative Study Review
Prefoldin (PFD) is a heterohexameric molecular chaperone which bind unfolded proteins and subsequently deliver them to a group II chaperonin for correct folding. Although there is structural and functional information available for humans and archaea PFDs, their existence and functions in malaria parasite remains uncharacterized. In the present review, we have collected the available information on prefoldin family members of archaea and humans and attempted to analyze unexplored PFD subunits of (). Our review enhances the understanding of probable functions, structure and mechanism of substrate binding of prefoldin by comparing with the available information of its homologs in archaea and . Three PFD out of six and a prefoldin-like protein are reported to be essential for parasite survival that signifies their importance in malaria parasite biology. Transcriptome analyses suggest that PFD subunits are up-regulated at the mRNA level during asexual and sexual stages of parasite life cycle. Our analysis suggested several pivotal proteins like myosin E, cytoskeletal protein (tubulin), merozoite surface protein and ring exported protein 3 as their interacting partners. Based on structural information of archaeal and PFDs, counterparts have been modelled and key interface residues were identified that are critical for oligomerization of PFD subunits. We collated information on PFD-substrate binding and PFD-chaperonin interaction in detail to understand the mechanism of substrate delivery in archaea and humans. Overall, our review enables readers to view the PFD family comprehensively. Communicated by Ramaswamy H. Sarma HSP: Heat shock proteins; CCT: Chaperonin containing TCP-1; PFD: Prefoldin; PFLP: Prefoldin like protein; PfPFD: Plasmodium falciparum prefoldin; Pf: Plasmodium falciparum; H. sapiens: Homo sapiens; M. thermoautotrophicus: Methanobacterium thermoautotrophicus; P. horikoshii: Pyrococcus horikoshii.
Topics: Archaea; Chaperonins; Eukaryota; Humans; Malaria; Molecular Chaperones; Plasmodium falciparum
PubMed: 33272134
DOI: 10.1080/07391102.2020.1850527 -
Methods in Molecular Biology (Clifton,... 2019Malaria continues to be a global health burden, threatening over 40% of the world's population. Drug resistance in Plasmodium falciparum, the etiological agent of the...
Malaria continues to be a global health burden, threatening over 40% of the world's population. Drug resistance in Plasmodium falciparum, the etiological agent of the majority of human malaria cases, is compromising elimination efforts. New approaches to treating drug-resistant malaria benefit from defining resistance liabilities of known antimalarial agents and compounds in development and defining genetic changes that mediate loss of parasite susceptibility. Here, we present protocols for in vitro selection of drug-resistant parasites and for site-directed gene editing of candidate resistance mediators to test for causality.
Topics: Animals; Antimalarials; CRISPR-Cas Systems; Gene Editing; Humans; Malaria, Falciparum; Plasmodium falciparum
PubMed: 31267498
DOI: 10.1007/978-1-4939-9550-9_9 -
Molecular and Biochemical Parasitology Jun 2024Malaria poses a significant global health threat particularly due to the prevalence of Plasmodium falciparum infection. With the emergence of parasite resistance to... (Review)
Review
Malaria poses a significant global health threat particularly due to the prevalence of Plasmodium falciparum infection. With the emergence of parasite resistance to existing drugs including the recently discovered artemisinin, ongoing research seeks novel therapeutic avenues within the malaria parasite. Proteases are promising drug targets due to their essential roles in parasite biology, including hemoglobin digestion, merozoite invasion, and egress. While exploring the genomic landscape of Plasmodium falciparum, it has been revealed that there are 92 predicted proteases, with only approximately 14 of them having been characterized. These proteases are further distributed among 26 families grouped into five clans: aspartic proteases, cysteine proteases, metalloproteases, serine proteases, and threonine proteases. Focus on metalloprotease class shows further role in organelle processing for mitochondria and apicoplasts suggesting the potential of metalloproteases as viable drug targets. Holistic understanding of the parasite intricate life cycle and identification of potential drug targets are essential for developing effective therapeutic strategies against malaria and mitigating its devastating global impact.
Topics: Plasmodium falciparum; Antimalarials; Metalloproteases; Humans; Protozoan Proteins; Malaria, Falciparum; Protease Inhibitors; Peptide Hydrolases
PubMed: 38554736
DOI: 10.1016/j.molbiopara.2024.111617 -
MBio Apr 2017The emergence and spread in Southeast Asia of resistance to artemisinin (ART) derivatives, the cornerstone of first-line artemisinin-based combination therapies (ACTs),...
The emergence and spread in Southeast Asia of resistance to artemisinin (ART) derivatives, the cornerstone of first-line artemisinin-based combination therapies (ACTs), underscore the urgent need to identify suitable replacement drugs. Discovery and development efforts have identified a series of ozonides with attractive chemical and pharmacological properties that are being touted as suitable replacements. Partial resistance to ART, defined as delayed parasite clearance in malaria patients treated with an ART derivative or an ACT, has been associated with mutations in the gene. In light of reports showing that ART derivatives and ozonides share similar modes of action, we have investigated whether parasites expressing mutant K13 are cross-resistant to the ozonides OZ439 (artefenomel) and OZ227 (arterolane). This work used a panel of culture-adapted clinical isolates from Cambodia that were genetically edited to express variant forms of K13. Phenotypic analyses employed ring-stage survival assays (ring-stage survival assay from 0 to 3 h [RSA]), whose results have earlier been shown to correlate with parasite clearance rates in patients. Our results document cross-resistance between OZ277 and dihydroartemisinin (DHA), a semisynthetic derivative of ART, in parasites carrying the K13 mutations C580Y, R539T, and I543T. For OZ439, we observed cross-resistance only for parasites that carried the rare K13 I543T mutation, with no evidence of cross-resistance afforded by the prevalent C580Y mutation. Mixed-culture competition experiments with isogenic lines carrying modified revealed variable growth deficits depending on the K13 mutation and parasite strain and provide a rationale for the broad dissemination of the fitness-neutral K13 C580Y mutation throughout strains currently circulating in Southeast Asia. ACTs have helped halve the malaria disease burden in recent years; however, emerging resistance to ART derivatives threatens to reverse this substantial progress. Resistance is driven primarily by mutations in the gene. These mutations pose a threat to ozonides, touted as promising alternatives to ARTs that share a similar mode of action. We report that DHA was considerably more potent than OZ439 and OZ277 against ART-sensitive asexual blood-stage parasites cultured We also document that mutant K13 significantly compromised the activity of the registered drug OZ277. In contrast, OZ439 remained effective against most parasite lines expressing mutant K13, with the exception of I543T that merits further monitoring in field-based OZ439 efficacy studies. K13 mutations differed considerably in their impact on parasite growth rates, in a strain-dependent context, with the most prevalent C580Y mutation being fitness neutral in recently culture-adapted strains from Cambodia, the epicenter of emerging ART resistance.
Topics: Antimalarials; Artemisinins; Cambodia; Cell Survival; Drug Resistance; Heterocyclic Compounds; Humans; Malaria, Falciparum; Mutation, Missense; Plasmodium falciparum; Protozoan Proteins; Virulence
PubMed: 28400526
DOI: 10.1128/mBio.00172-17 -
Scientific Reports Feb 2019Plasmodium falciparum histidine-rich proteins 2 (PfHRP2) based RDTs are advocated in falciparum malaria-endemic regions, particularly when quality microscopy is not...
Plasmodium falciparum histidine-rich proteins 2 (PfHRP2) based RDTs are advocated in falciparum malaria-endemic regions, particularly when quality microscopy is not available. However, diversity and any deletion in the pfhrp2 and pfhrp3 genes can affect the performance of PfHRP2-based RDTs. A total of 400 samples collected from uncomplicated malaria cases from Kenya were investigated for the amino acid repeat profiles in exon 2 of pfhrp2 and pfhrp3 genes. In addition, PfHRP2 levels were measured in 96 individuals with uncomplicated malaria. We observed a unique distribution pattern of amino acid repeats both in the PfHRP2 and PfHRP3. 228 PfHRP2 and 124 PfHRP3 different amino acid sequences were identified. Of this, 214 (94%) PfHRP2 and 81 (65%) PfHRP3 amino acid sequences occurred only once. Thirty-nine new PfHRP2 and 20 new PfHRP3 amino acid repeat types were identified. PfHRP2 levels were not correlated with parasitemia or the number of PfHRP2 repeat types. This study shows the variability of PfHRP2, PfHRP3 and PfHRP2 concentration among uncomplicated malaria cases. These findings will be useful to understand the performance of PfHRP2-based RDTs in Kenya.
Topics: Amino Acid Sequence; Antigens, Protozoan; Diagnostic Tests, Routine; Evolution, Molecular; Exons; Humans; Kenya; Malaria, Falciparum; Plasmodium falciparum; Protozoan Proteins
PubMed: 30737461
DOI: 10.1038/s41598-018-38175-1 -
Current Topics in Microbiology and... 2019The global spread of artemisinin resistance brings with it the threat of incurable malaria. Already, this disease threatens over 219 million lives per year and causes... (Review)
Review
The global spread of artemisinin resistance brings with it the threat of incurable malaria. Already, this disease threatens over 219 million lives per year and causes 5-6% losses in GDP in endemic areas, even with current advances in prevention and treatment. This chapter discusses the currently tenuous position we are in globally, and the impact that could be seen if artemisinin treatment is lost, whether due to the unchecked spread of K13 mutations or poor global investment in treatment and prevention advances. Artemisinin is the backbone of current ACT treatment programs and severe malarial treatment; without it, the success of future malaria eradication programs will be in jeopardy.
Topics: Antimalarials; Artemisinins; Drug Resistance; Epidemiological Monitoring; Humans; Malaria, Falciparum; Plasmodium falciparum
PubMed: 31218504
DOI: 10.1007/82_2019_163 -
Nature Communications Feb 2024Ribonucleoprotein complexes are composed of RNA, RNA-dependent proteins (RDPs) and RNA-binding proteins (RBPs), and play fundamental roles in RNA regulation. However, in...
Ribonucleoprotein complexes are composed of RNA, RNA-dependent proteins (RDPs) and RNA-binding proteins (RBPs), and play fundamental roles in RNA regulation. However, in the human malaria parasite, Plasmodium falciparum, identification and characterization of these proteins are particularly limited. In this study, we use an unbiased proteome-wide approach, called R-DeeP, a method based on sucrose density gradient ultracentrifugation, to identify RDPs. Quantitative analysis by mass spectrometry identifies 898 RDPs, including 545 proteins not yet associated with RNA. Results are further validated using a combination of computational and molecular approaches. Overall, this method provides the first snapshot of the Plasmodium protein-protein interaction network in the presence and absence of RNA. R-DeeP also helps to reconstruct Plasmodium multiprotein complexes based on co-segregation and deciphers their RNA-dependence. One RDP candidate, PF3D7_0823200, is functionally characterized and validated as a true RBP. Using enhanced crosslinking and immunoprecipitation followed by high-throughput sequencing (eCLIP-seq), we demonstrate that this protein interacts with various Plasmodium non-coding transcripts, including the var genes and ap2 transcription factors.
Topics: Humans; RNA; Plasmodium falciparum; Proteome; RNA-Binding Proteins; Plasmodium
PubMed: 38355719
DOI: 10.1038/s41467-024-45519-1 -
Proceedings of the National Academy of... Mar 2017Artemisinin-resistant falciparum malaria, defined by a slow-clearance phenotype and the presence of mutants, has emerged in the Greater Mekong Subregion. Naturally...
Artemisinin-resistant falciparum malaria, defined by a slow-clearance phenotype and the presence of mutants, has emerged in the Greater Mekong Subregion. Naturally acquired immunity to malaria clears parasites independent of antimalarial drugs. We hypothesized that between- and within-population variations in host immunity influence parasite clearance after artemisinin treatment and the interpretation of emerging artemisinin resistance. Antibodies specific to 12 sporozoite and blood-stage antigens were determined in 959 patients (from 11 sites in Southeast Asia) participating in a multinational cohort study assessing parasite clearance half-life (PCt) after artesunate treatment and mutations. Linear mixed-effects modeling of pooled individual patient data assessed the association between antibody responses and PCt antibodies were lowest in areas where the prevalence of mutations and slow PCt were highest [Spearman ρ = -0.90 (95% confidence interval, -0.97, -0.65), and Spearman ρ = -0.94 (95% confidence interval, -0.98, -0.77), respectively]. antibodies were associated with faster PCt (mean difference in PCt according to seropositivity, -0.16 to -0.65 h, depending on antigen); antibodies have a greater effect on the clearance of mutant compared with wild-type parasites (mean difference in PCt according to seropositivity, -0.22 to -0.61 h faster in mutants compared with wild-type parasites). Naturally acquired immunity accelerates the clearance of artemisinin-resistant parasites in patients with falciparum malaria and may confound the current working definition of artemisinin resistance. Immunity may also play an important role in the emergence and transmission potential of artemisinin-resistant parasites.
Topics: Adolescent; Adult; Aged; Antimalarials; Artemisinins; Asia; Child; Child, Preschool; Cohort Studies; Drug Resistance; Female; Humans; Infant; Malaria, Falciparum; Male; Middle Aged; Phenotype; Plasmodium falciparum; Young Adult
PubMed: 28289193
DOI: 10.1073/pnas.1615875114