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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 -
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 -
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 -
Pathogens and Disease Jul 2022In order to survive and establish infection, the Plasmodium parasite employs various strategies to evade the host immune response. The var genes family, a repertoire of...
In order to survive and establish infection, the Plasmodium parasite employs various strategies to evade the host immune response. The var genes family, a repertoire of 60 genes, expresses parasite-specific protein PfEMP1, a variable surface antigen, on the membrane of infected erythrocytes, and by continuously switching the variants of PfEMP1, help the parasite to avoid detection and destruction by the host immune system during the intra-erythrocytic developmental cycle. Although chromatin modifications are recognised to be a prominent phenomenon in regulation of mono-allelic expression of these var genes, the precise histone codes and molecular players and mechanisms guiding these modifications have yet to be unravelled in depth. In this study, we have functionally characterised RUVBL proteins of Plasmodium falciparum and shown that PfMYST (an essential lysine acetyl transferase) and PfRUVBL protein complex occupy the TARE region and var gene promoter in the ring stage of the parasite. Further, we have demonstrated that the PfMYST/PfRUVBL complex interacts with core histones, H3 and H4. Overall the findings of this study add further information by identifying the potential role of epigenetic regulators, PfMYST and PfRUVBL, in the regulation of monoallelic expression of var genes in the malaria parasite.
Topics: Erythrocytes; Histones; Plasmodium falciparum; Protozoan Proteins
PubMed: 35640888
DOI: 10.1093/femspd/ftac018 -
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 -
Scientific Reports Nov 2020A variety of post-translational modifications of Plasmodium falciparum proteins, including phosphorylation and ubiquitination, are shown to have key regulatory roles...
A variety of post-translational modifications of Plasmodium falciparum proteins, including phosphorylation and ubiquitination, are shown to have key regulatory roles during parasite development. NEDD8 is a ubiquitin-like modifier of cullin-RING E3 ubiquitin ligases, which regulates diverse cellular processes. Although neddylation is conserved in eukaryotes, it is yet to be characterized in Plasmodium and related apicomplexan parasites. We characterized P. falciparum NEDD8 (PfNEDD8) and identified cullins as its physiological substrates. PfNEDD8 is a 76 amino acid residue protein without the C-terminal tail, indicating that it can be readily conjugated. The wild type and mutant (Gly75Ala/Gly76Ala) PfNEDD8 were expressed in P. falciparum. Western blot of wild type PfNEDD8-expressing parasites indicated multiple high molecular weight conjugates, which were absent in the parasites expressing the mutant, indicating conjugation of NEDD8 through Gly76. Immunoprecipitation followed by mass spectrometry of wild type PfNEDD8-expressing parasites identified two putative cullins. Furthermore, we expressed PfNEDD8 in mutant S. cerevisiae strains that lacked endogenous NEDD8 (rub1Δ) or NEDD8 conjugating E2 enzyme (ubc12Δ). The PfNEDD8 immunoprecipitate also contained S. cerevisiae cullin cdc53, further substantiating cullins as physiological substrates of PfNEDD8. Our findings lay ground for investigation of specific roles and drug target potential of neddylation in malaria parasites.
Topics: Cullin Proteins; Databases, Genetic; NEDD8 Protein; Plasmodium falciparum; Protozoan Proteins
PubMed: 33214620
DOI: 10.1038/s41598-020-77001-5 -
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 -
Current Opinion in Microbiology Feb 2023The apicoplast of Plasmodium falciparum is the only source of essential isoprenoid precursors and Coenzyme A (CoA) in the parasite. Isoprenoid precursor synthesis relies... (Review)
Review
The apicoplast of Plasmodium falciparum is the only source of essential isoprenoid precursors and Coenzyme A (CoA) in the parasite. Isoprenoid precursor synthesis relies on the iron-sulfur cluster (FeS) cofactors produced within the apicoplast, rendering FeS synthesis an essential function of this organelle. Recent reports provide important insights into the roles of FeS cofactors and the use of isoprenoid precursors and CoA both inside and outside the apicoplast. Here, we review the recent insights into the roles of these metabolites in blood-stage malaria parasites and discuss new questions that have been raised in light of these discoveries.
Topics: Animals; Humans; Apicoplasts; Parasites; Malaria; Plasmodium falciparum; Terpenes; Protozoan Proteins
PubMed: 36563485
DOI: 10.1016/j.mib.2022.102255 -
Tropical Biomedicine Sep 2020Malaria is one of the most dangerous infectious diseases due to its high infection and mortality rates, especially in the tropical belt. Plasmodium falciparum (P.... (Review)
Review
Malaria is one of the most dangerous infectious diseases due to its high infection and mortality rates, especially in the tropical belt. Plasmodium falciparum (P. falciparum), the most virulent malaria parasite in humans, was recently reported to develop resistance against the final efficient antimalarial drug, artemisinin. Little is known about the resistance mechanisms, which further complicates the problem as a proper counteraction is unable to be taken. Hence, the understanding of drug mode of action and its molecular target is valuable knowledge that needs to be considered to develop the next generation of antimalarial drugs. P. falciparum protein kinase (Pf PK) is an attractive target for antimalarial chemotherapy due to its vital roles in all P. falciparum life stages. Moreover, overall structural differences and the presence of unique Pf PKs that are absent in human kinome, suggesting specific inhibition of Pf PK without affecting human cells is achievable. To date, at least 86 eukaryotic protein kinases have been identified in P. falciparum kinome, by which less than 40 were validated as potential targets at the erythrocytes stage. In this review, recent progress of the furthest validated Pf PKs; Pf Nek-1, Pf CDPK1, Pf CDPK4, Pf PKG, and Pf CLK-3 will be briefly discussed.
Topics: Antimalarials; Humans; Malaria, Falciparum; Plasmodium falciparum; Protein Kinase Inhibitors; Protein Kinases
PubMed: 33612795
DOI: 10.47665/tb.37.3.822