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The Journal of Infectious Diseases May 2021Artemisinin monotherapy of Plasmodium falciparum infection is frequently ineffective due to recrudescence. Artemisinin-induced dormancy, shown in vitro and in animal...
BACKGROUND
Artemisinin monotherapy of Plasmodium falciparum infection is frequently ineffective due to recrudescence. Artemisinin-induced dormancy, shown in vitro and in animal models, provides a plausible explanation. To date, direct evidence of artemisinin-induced dormancy in humans is lacking.
METHODS
Blood samples were collected from Plasmodium falciparum 3D7- or K13-infected participants before and 48-72 hours after single-dose artesunate (AS) treatment. Parasite morphology, molecular signature of dormancy, capability and dynamics of seeding in vitro cultures, and genetic mutations in the K13 gene were investigated.
RESULTS
Dormant parasites were observed in post-AS blood samples of 3D7- and K13-infected participants. The molecular signature of dormancy, an up-regulation of acetyl CoA carboxylase, was detected in 3D7 and K13 samples post-AS, but not in pre-AS samples. Posttreatment samples successfully seeded in vitro cultures, with a significant delay in time to reach 2% parasitemia compared to pretreatment samples.
CONCLUSIONS
This study provides strong evidence for the presence of artemisinin-induced dormant parasites in P. falciparum infections. These parasites are a likely reservoir for recrudescent infection following artemisinin monotherapy and artemisinin combination therapy (ACT). Combination regimens that target dormant parasites or remain at therapeutic levels for a sufficient time to kill recovering parasites will likely improve efficacy of ACTs.
Topics: Antimalarials; Artesunate; Drug Resistance; Humans; Malaria, Falciparum; Plasmodium falciparum; Protozoan Proteins
PubMed: 32901248
DOI: 10.1093/infdis/jiaa562 -
Current Opinion in Microbiology Jun 2023Fever is a part of the human innate immune response that contributes to limiting microbial growth and development in many infectious diseases. For the parasite... (Review)
Review
Fever is a part of the human innate immune response that contributes to limiting microbial growth and development in many infectious diseases. For the parasite Plasmodium falciparum, survival of febrile temperatures is crucial for its successful propagation in human populations as well as a fundamental aspect of malaria pathogenesis. This review discusses recent insights into the biological complexity of the malaria parasite's heat-shock response, which involves many cellular compartments and essential metabolic processes to alleviate oxidative stress and accumulation of damaged and unfolded proteins. We highlight the overlap between heat-shock and artemisinin resistance responses, while also explaining how the malaria parasite adapts its fever response to fight artemisinin treatment. Additionally, we discuss how this systemic and essential fight for survival can also contribute to parasite transmission to mosquitoes.
Topics: Animals; Humans; Parasites; Plasmodium falciparum; Artemisinins; Malaria; Heat-Shock Response; Malaria, Falciparum; Protozoan Proteins
PubMed: 37130502
DOI: 10.1016/j.mib.2023.102322 -
Turkiye Parazitolojii Dergisi Dec 2020is a protozoan parasite that causes many deaths worldwide. It's cultivation in an in vitro culture setting contributes significantly to scientific studies. However,...
OBJECTIVE
is a protozoan parasite that causes many deaths worldwide. It's cultivation in an in vitro culture setting contributes significantly to scientific studies. However, there are no laboratories in Turkey that cultivate . Hence, the purpose of this study was to cultivate .
METHODS
Five strains were used in our study and were kept frozen in liquid nitrogen tanks. These parasite strains were then thawed in a 37 °C water bath and transferred to the Albumax-complete medium that was previously prepared. After that, the petri dishes were placed in the chamber. For 30 seconds, a special gas mixture containing 5% CO, 5% O and 90% N was added into the chamber which was placed in a 37 °C oven and left for incubation for 2 days. At the end of the incubation period, thin smear preparations were prepared from the medium, stained with Giemsa and examined using an immersion lens.
RESULTS
Examination of the smears revealed that trophozoite and schizont forms of all isolates were present at a rate of 2% in culture medium.
CONCLUSION
As a result of our study, the culture of was successfully developed. With this, several projects such as biological and chemical characteristics, pathogenicity, phenotypic and molecular-level drug sensitivities and parasite vaccination studies can be carried out more easily in our country.
Topics: Animals; Culture Media; Humans; In Vitro Techniques; Plasmodium falciparum; Schizonts; Trophozoites; Turkey
PubMed: 33269565
DOI: 10.4274/tpd.galenos.2020.7148 -
Protein Science : a Publication of the... Nov 2020PfSERA5, a significantly abundant protein present within the parasitophorous vacuole (PV) and essential for normal growth during the blood-stage life cycle of the...
PfSERA5, a significantly abundant protein present within the parasitophorous vacuole (PV) and essential for normal growth during the blood-stage life cycle of the malaria parasite Plasmodium falciparum, displays structural similarity to many other cysteine proteases. However, PfSERA5 does not exhibit any detectable protease activity and therefore the role of the PfSERA5 papain-like domain (PfSERA5E), thought to remain bound to its cognate prodomain, remains unknown. In this study, we present a revised structure of the central PfSERA5E domain at a resolution of 1.2 Å, and the first structure of the "zymogen" of this papain-like domain including its cognate prodomain (PfSERA5PE) to 2.2 Å resolution. PfSERA5PE is somewhat structurally similar to that of other known proenzymes, retaining the conserved overall folding and orientation of the prodomain through, and occluding, the archetypal papain-like catalytic triad "active-site" cleft, in the same reverse direction as conventional prodomains. Our findings are congruent with previously identified structures of PfSERA5E and of similar "zymogens" and provide a foundation for further investigation into the function of PfSERA5.
Topics: Antigens, Protozoan; Crystallography, X-Ray; Enzyme Precursors; Plasmodium falciparum; Protein Domains
PubMed: 32955133
DOI: 10.1002/pro.3956 -
Journal of Proteome Research Feb 2021is the main causative agent of human malaria. During the intraerythrocytic development cycle, the morphology changes dramatically from circulating young rings to...
is the main causative agent of human malaria. During the intraerythrocytic development cycle, the morphology changes dramatically from circulating young rings to sequestered mature trophozoites and schizonts. Sequestered forms contribute to the pathophysiology of severe malaria as the infected erythrocytes obstruct the microvascular flow in deep organs and induce local inflammation. However, the sequestration mechanism limits the access to the corresponding parasitic form in the clinical samples from patients infected with . To complement this deficiency, we aimed to evaluate the relevance of mRNA study as a proxy of protein expression in sequestered parasites. To do so, we conducted a proteotranscriptomic analysis using five independent laboratory strain samples. RNA sequencing was performed, and the mRNA expression level was assessed on circulating ring-stage parasites. The level of protein expression were measured by LC-MS/MS on the corresponding sequestered mature forms after 18-24 h of maturation. Overall, our results showed a strong transcriptome/transcriptome and a very strong proteome/proteome correlation between samples. Moreover, positive correlations of mRNA and protein expression levels were found between ring-stage transcriptomes and mature form proteomes. However, twice more transcripts were identified at the ring stage than proteins at the mature trophozoite stage. A high level of transcript expression did not guarantee the detection of the corresponding protein. Finally, we pointed out discrepancies at the individual gene level. Taken together, our results show that transcript and protein expressions are overall correlated. However, mRNA abundance is not a perfect proxy of protein expression at the individual level. Importantly, our study shows limitations of the "blind" use of RNA-seq and the importance of multiomics approaches for blood stage study in clinical samples.
Topics: Chromatography, Liquid; Erythrocytes; Humans; Malaria, Falciparum; Plasmodium falciparum; Tandem Mass Spectrometry
PubMed: 33475364
DOI: 10.1021/acs.jproteome.0c00496 -
Malaria Journal Jul 2021Early malaria diagnosis and its profiling require the development of new sensing platforms enabling rapid and early analysis of parasites in blood or saliva, aside the...
BACKGROUND
Early malaria diagnosis and its profiling require the development of new sensing platforms enabling rapid and early analysis of parasites in blood or saliva, aside the widespread rapid diagnostic tests (RDTs).
METHODS
This study shows the performance of a cost-effective optical fiber-based solution to target the presence of Plasmodium falciparum histidine-rich protein 2 (PfHRP2). Unclad multimode optical fiber probes are coated with a thin gold film to excite Surface Plasmon Resonance (SPR) yielding high sensitivity to bio-interactions between targets and bioreceptors grafted on the metal surface.
RESULTS
Their performances are presented in laboratory conditions using PBS spiked with growing concentrations of purified target proteins and within in vitro cultures. Two probe configurations are studied through label-free detection and amplification using secondary antibodies to show the possibility to lower the intrisic limit of detection.
CONCLUSIONS
As malaria hits millions of people worldwide, the improvement and multiplexing of this optical fiber technique can be of great interest, especially for a future purpose of using multiple receptors on the fiber surface or several coated-nanoparticles as amplifiers.
Topics: Antigens, Protozoan; Biosensing Techniques; Humans; Optical Fibers; Plasmodium falciparum; Protozoan Proteins
PubMed: 34320995
DOI: 10.1186/s12936-021-03863-3 -
Parasitology International Dec 2021Malaria is a haemato-protozoan disease which causes thousands of deaths every year. Due to the alarming increase of drug resistant strains of P. falciparum, malaria is...
Malaria is a haemato-protozoan disease which causes thousands of deaths every year. Due to the alarming increase of drug resistant strains of P. falciparum, malaria is now becoming more deadly. Helicases are the most important components of the cellular machinery without which cells are unable to survive. The importance of helicases has been proven in variety of organisms. In this study we have reported detailed biochemical characterization of human homologue of DDX3X from Plasmodium falciparum (PfDDX3X). Our study revealed that PfDDX3X is ATP- dependent DNA helicase whereas in human host it is ATP-dependent RNA helicase. We show that N-terminal is essential for its activity and it is present in nucleus and cytoplasm in intraerythrocytic developmental stages of P. falciparum 3D7 strain. Also, it is highly expressed in the schizont stage of P. falciparum 3D7strain. The present study suggests that a protein can perform different functions in different systems. The present study will help to understand the basic biology of malaria parasite P. falciparum.
Topics: Amino Acid Sequence; DNA Helicases; Malaria, Falciparum; Phylogeny; Plasmodium falciparum; Protozoan Proteins; Schizonts; Sequence Alignment
PubMed: 34265466
DOI: 10.1016/j.parint.2021.102420 -
Plasmodium falciparum Cysteine Rich Secretory Protein uniquely localizes to one end of male gametes.Molecular and Biochemical Parasitology Mar 2022Fertilization is a central event during the life cycle of most eukaryotic organisms and involves gamete recognition and fusion, ultimately resulting in zygote formation....
Fertilization is a central event during the life cycle of most eukaryotic organisms and involves gamete recognition and fusion, ultimately resulting in zygote formation. Gamete fertilization in the malaria-causing Plasmodium parasites occurs inside the mosquito midgut and represents a major bottleneck in the life cycle. Cysteine Rich Secretory Proteins (CRISPs) are key molecules involved in fertilization in vertebrates and the presence of a CRISP ortholog in human malaria infective Plasmodium falciparum suggested a possible role in fertilization. Strikingly, P. falciparum CRISP exhibited a unique terminal localization in the male microgamete. Parasites with a CRISP gene deletion (P. falciparum crisp) proliferated asexually similar to wildtype NF54 parasites and differentiated into gametocytes. Further analysis showed that Plasmodium falciparum crisp gametocytes underwent exflagellation to form male gametes and no apparent defect in transmission to the mosquito vector was observed. These data show that P. falciparum CRISP is a marker for the apical end of the microgamete and that it might only have an ancillary or redundant function in the male sexual stages.
Topics: Animals; Cysteine; Germ Cells; Humans; Life Cycle Stages; Malaria; Malaria, Falciparum; Male; Mosquito Vectors; Parasites; Plasmodium falciparum
PubMed: 34998927
DOI: 10.1016/j.molbiopara.2022.111447 -
Nature Communications Jun 2021Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The... (Comparative Study)
Comparative Study
Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The unusual mitochondrion of malaria parasites is a validated drug target but remains poorly understood. Here, we apply complexome profiling to map the inventory of protein complexes across the pathogenic asexual blood stages and the transmissible gametocyte stages of Plasmodium falciparum. We identify remarkably divergent composition and clade-specific additions of all respiratory chain complexes. Furthermore, we show that respiratory chain complex components and linked metabolic pathways are up to 40-fold more prevalent in gametocytes, while glycolytic enzymes are substantially reduced. Underlining this functional switch, we find that cristae are exclusively present in gametocytes. Leveraging these divergent properties and stage dynamics for drug development presents an attractive opportunity to discover novel classes of antimalarials and increase our repertoire of gametocytocidal drugs.
Topics: Electron Transport Chain Complex Proteins; Evolution, Molecular; Life Cycle Stages; Mitochondria; Mitochondrial Proteins; Multiprotein Complexes; Oxidative Phosphorylation; Plasmodium falciparum; Protozoan Proteins; Species Specificity
PubMed: 34155201
DOI: 10.1038/s41467-021-23919-x -
Trends in Genetics : TIG Jan 2021Multiple hosts and various life cycle stages prompt the human malaria parasite, Plasmodium falciparum, to acquire sophisticated molecular mechanisms to ensure its... (Review)
Review
Multiple hosts and various life cycle stages prompt the human malaria parasite, Plasmodium falciparum, to acquire sophisticated molecular mechanisms to ensure its survival, spread, and transmission to its next host. To face these environmental challenges, increasing evidence suggests that the parasite has developed complex and complementary layers of regulatory mechanisms controlling gene expression. Here, we discuss the recent developments in the discovery of molecular components that contribute to cell replication and differentiation and highlight the major contributions of epigenetics, transcription factors, and nuclear architecture in controlling gene regulation and life cycle progression in Plasmodium spp.
Topics: Animals; Chromatin; Epigenesis, Genetic; Gene Expression Regulation; Host-Parasite Interactions; Humans; Malaria, Falciparum; Plasmodium falciparum; Transcription Factors
PubMed: 32988634
DOI: 10.1016/j.tig.2020.09.003