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Journal of Natural Products Apr 2024Three new antiplasmodial compounds, named akedanones A (), B (), and C (), were discovered from the cultured material of sp. K20-0187 isolated from a soil sample...
Three new antiplasmodial compounds, named akedanones A (), B (), and C (), were discovered from the cultured material of sp. K20-0187 isolated from a soil sample collected at Takeda, Kofu, Yamanashi prefecture in Japan. The structures of compounds - were elucidated as new 2,3-dihydronaphthoquinones having prenyl and reverse prenyl groups by mass spectrometry and nuclear magnetic resonance analyses. Compound and the known furanonaphthoquinone I () showed potent antiplasmodial activity against chloroquine-sensitive and chloroquine-resistant strains, with half-maximal inhibitory concentration values ranging from 0.06 to 0.3 μM. Compounds and also displayed potent antiplasmodial activity against drug-sensitive rodent malaria N strain, with inhibition rates of 47.6 and 43.1%, respectively, on intraperitoneal administration at a dose of 5 mg kg day for 4 days.
Topics: Antimalarials; Plasmodium falciparum; Streptomyces; Naphthoquinones; Molecular Structure; Plasmodium berghei; Animals; Japan; Mice; Chloroquine; Soil Microbiology
PubMed: 38421618
DOI: 10.1021/acs.jnatprod.3c01285 -
Molecular Microbiology May 2024Plasmodium is an obligate intracellular parasite that requires intense lipid synthesis for membrane biogenesis and survival. One of the principal membrane components is...
Plasmodium is an obligate intracellular parasite that requires intense lipid synthesis for membrane biogenesis and survival. One of the principal membrane components is oleic acid, which is needed to maintain the membrane's biophysical properties and fluidity. The malaria parasite can modify fatty acids, and stearoyl-CoA Δ9-desaturase (Scd) is an enzyme that catalyzes the synthesis of oleic acid by desaturation of stearic acid. Scd is dispensable in P. falciparum blood stages; however, its role in mosquito and liver stages remains unknown. We show that P. berghei Scd localizes to the ER in the blood and liver stages. Disruption of Scd in the rodent malaria parasite P. berghei did not affect parasite blood stage propagation, mosquito stage development, or early liver-stage development. However, when Scd KO sporozoites were inoculated intravenously or by mosquito bite into mice, they failed to initiate blood-stage infection. Immunofluorescence analysis revealed that organelle biogenesis was impaired and merozoite formation was abolished, which initiates blood-stage infections. Genetic complementation of the KO parasites restored merozoite formation to a level similar to that of WT parasites. Mice immunized with Scd KO sporozoites confer long-lasting sterile protection against infectious sporozoite challenge. Thus, the Scd KO parasite is an appealing candidate for inducing protective pre-erythrocytic immunity and hence its utility as a GAP.
Topics: Plasmodium berghei; Animals; Mice; Organelle Biogenesis; Liver; Merozoites; Malaria; Stearoyl-CoA Desaturase; Sporozoites; Protozoan Proteins; Anopheles; Female; Endoplasmic Reticulum
PubMed: 38419272
DOI: 10.1111/mmi.15246 -
MBio Apr 2024Neddylation is a type of posttranslational modification known to regulate a wide range of cellular processes by covalently conjugating the ubiquitin-like protein Nedd8...
Neddylation is a type of posttranslational modification known to regulate a wide range of cellular processes by covalently conjugating the ubiquitin-like protein Nedd8 to target proteins at lysine residues. However, the role of neddylation in malaria parasites has not been determined. Here, for the first time, we showed that neddylation plays an essential role in malaria transmission in . We found that disruption of Nedd8 did not affect blood-stage propagation, gametocyte development, gamete formation, or zygote formation while abolishing the formation of ookinetes and further transmission of the parasites in mosquitoes. These phenotypic defects in Nedd8 knockout parasites were complemented by reintroducing the gene that restored mosquito transmission to wild-type levels. Our data establish the role of Nedd8 in malaria parasite transmission.IMPORTANCENeddylation is a process by which Nedd8 is covalently attached to target proteins through three-step enzymatic cascades. The attachment of Nedd8 residues results in a range of diverse functions, such as cell cycle regulation, metabolism, immunity, and tumorigenesis. The potential neddylation substrates are cullin (CUL) family members, which are implicated in controlling the cell cycle. Cullin neddylation leads to the activation of cullin-RING ubiquitin ligases, which regulate a myriad of biological processes through target-specific ubiquitylation. Neddylation possibly regulates meiosis in zygotes, which subsequently develop into ookinetes. Our findings point to an essential function of this neddylation pathway and highlight its possible importance in designing novel intervention strategies.
Topics: Animals; Ubiquitins; Plasmodium berghei; Cullin Proteins; Ubiquitin; Ubiquitin-Protein Ligases
PubMed: 38411954
DOI: 10.1128/mbio.00232-24 -
Scientific Reports Feb 2024Malaria can have severe long-term effects. Even after treatment with antimalarial drugs eliminates the parasite, survivors of cerebral malaria may suffer from...
Malaria can have severe long-term effects. Even after treatment with antimalarial drugs eliminates the parasite, survivors of cerebral malaria may suffer from irreversible brain damage, leading to cognitive deficits. Angiotensin II, a natural human peptide hormone that regulates blood pressure, has been shown to be active against Plasmodium spp., the etiologic agent of malaria. Here, we tested two Ang II derivatives that do not elicit vasoconstriction in mice: VIPF, a linear tetrapeptide, which constitutes part of the hydrophobic portion of Ang II; and Ang II-SS, a disulfide-bridged derivative. The antiplasmodial potential of both peptides was evaluated with two mouse models: an experimental cerebral malaria model and a mouse model of non-cerebral malaria. The latter consisted of BALB/c mice infected with Plasmodium berghei ANKA. The peptides had no effect on mean blood pressure and significantly reduced parasitemia in both mouse models. Both peptides reduced the SHIRPA score, an assay used to assess murine health and behavior. However, only the constrained derivative (Ang II-SS), which was also resistant to proteolytic degradation, significantly increased mouse survival. Here, we show that synthetic peptides derived from Ang II are capable of conferring protection against severe manifestations of malaria in mouse models while overcoming the vasoconstrictive side effects of the parent peptide.
Topics: Animals; Mice; Humans; Malaria, Cerebral; Angiotensin II; Disease Models, Animal; Antimalarials; Peptides; Plasmodium berghei; Mice, Inbred C57BL
PubMed: 38409185
DOI: 10.1038/s41598-024-51267-5 -
The Journal of Infectious Diseases Jun 2024Plasmodium falciparum and Plasmodium vivax account for >90% global malaria burden. Transmission intervention strategies encompassing transmission-blocking vaccines (TBV)...
BACKGROUND
Plasmodium falciparum and Plasmodium vivax account for >90% global malaria burden. Transmission intervention strategies encompassing transmission-blocking vaccines (TBV) and drugs represent ideal public health tools to eliminate malaria at the population level. The availability of mature P. falciparum gametocytes through in vitro culture has facilitated development of a standard membrane feeding assay to assess efficacy of transmission interventions against P. falciparum. The lack of in vitro culture for P. vivax has significantly hampered similar progress on P. vivax and limited studies have been possible using blood from infected patients in endemic areas. The ethical and logistical limitations of on-time access to blood from patients have impeded the development of P. vivax TBVs.
METHODS
Transgenic murine malaria parasites (Plasmodium berghei) expressing TBV candidates offer a promising alternative for evaluation of P. vivax TBVs through in vivo studies in mice, and ex vivo membrane feeding assay (MFA).
RESULTS
We describe the development of transmission-competent transgenic TgPbvs25 parasites and optimization of parameters to establish an ex vivo MFA to evaluate P. vivax TBV based on Pvs25 antigen.
CONCLUSIONS
The MFA is expected to expedite Pvs25-based TBV development without dependence on blood from P. vivax-infected patients in endemic areas for evaluation.
Topics: Animals; Malaria Vaccines; Plasmodium vivax; Malaria, Vivax; Plasmodium berghei; Mice; Antigens, Protozoan; Humans; Female; Antigens, Surface
PubMed: 38408353
DOI: 10.1093/infdis/jiae102 -
BioRxiv : the Preprint Server For... Feb 2024Plasmodium parasites, which are the causative agents of malaria, undergo closed mitosis without breakdown of the nuclear envelope. Unlike the closed mitosis in yeast, P....
Plasmodium parasites, which are the causative agents of malaria, undergo closed mitosis without breakdown of the nuclear envelope. Unlike the closed mitosis in yeast, P. berghei parasites undergo multiple rounds of asynchronous nuclear divisions in a shared cytoplasm result in a multinucleated (8-24) organism prior to formation of daughter cells within an infected red blood cell. During this replication process, intact nuclear pore complexes (NPCs) and their component nucleoporins are likely to play critical roles in parasite growth, facilitating selective bi-directional nucleocytoplasmic transport and genome organization. Here we utilize ultrastructure expansion microscopy (U-ExM) to investigate P. berghei Nup138, Nup221, and Nup313 at the single nucleus level throughout the 24 hour blood-stage replication cycle. Our findings reveal that these Nups are evenly distributed around the nuclei and organized in a rosette structure previously undescribed around the centriolar plaque, which is responsible for intranuclear microtubule nucleation during mitosis. We also detect an increased number of NPCs compared with previously reported, highlighting the power of U-ExM. By adapting the recombination-induced tag exchange (RITE) system to P. berghei, we provide evidence of NPC maintenance, demonstrating Nup221 turnover during parasite asexual replication. Our data shed light on the distribution of NPCs and their homeostasis during the blood-stage replication of P. berghei parasites. Further studies into the nuclear surface of these parasites will allow for a better understanding of parasites nuclear mechanics and organization.
PubMed: 38405843
DOI: 10.1101/2024.02.16.580747 -
Microorganisms Jan 2024Multi-protein complexes are crucial for various essential biological processes of the malaria parasite , such as protein synthesis, host cell invasion and adhesion.... (Review)
Review
Multi-protein complexes are crucial for various essential biological processes of the malaria parasite , such as protein synthesis, host cell invasion and adhesion. Especially during the sexual phase of the parasite, which takes place in the midgut of the mosquito vector, protein complexes are required for fertilization, sporulation and ultimately for the successful transmission of the parasite. Among the most noticeable protein complexes of the transmission stages are the ones formed by the LCCL domain-containing protein family that play critical roles in the generation of infective sporozoites. The six members of this protein family are characterized by numerous adhesive modules and domains typically found in secreted proteins. This review summarizes the findings of expression and functional studies on the LCCL domain-containing proteins of the human pathogenic and the rodent-infecting and discusses the common features and differences of the homologous proteins.
PubMed: 38399683
DOI: 10.3390/microorganisms12020279 -
Molecular Microbiology Mar 2024Plasmodium sporozoites are the highly motile and invasive forms of the malaria parasite transmitted by mosquitoes. Sporozoites form within oocysts at the midgut wall of...
Plasmodium sporozoites are the highly motile and invasive forms of the malaria parasite transmitted by mosquitoes. Sporozoites form within oocysts at the midgut wall of the mosquito, egress from oocysts and enter salivary glands prior to transmission. The GPI-anchored major surface protein, the circumsporozoite protein (CSP) is important for Plasmodium sporozoite formation, egress, migration and invasion. To visualize CSP, we previously generated full-length versions of CSP internally tagged with the green fluorescent protein, GFP. However, while these allowed for imaging of sporogony in oocysts, sporozoites failed to egress. Here, we explore different strategies to overcome this block in egress and obtain salivary gland resident sporozoites that express CSP-GFP. Replacing the N-terminal and repeat region with GFP did not allow sporozoite formation. Lowering expression of CSP-GFP at the endogenous locus allowed sporozoite formation but did not overcome egress block. Crossing of CSP-GFP expressing parasites that are blocked in egress with wild-type parasites yielded a small fraction of parasites that entered salivary glands and expressed various levels of CSP-GFP. Expressing CSP-GFP constructs from a silent chromosome region from promoters that are active only post salivary gland invasion yielded normal numbers of fluorescent salivary gland sporozoites, albeit with low levels of fluorescence. We also show that lowering CSP expression by 50% allowed egress from oocysts but not salivary gland entry. In conclusion, Plasmodium berghei parasites with normal CSP expression tolerate a certain level of CSP-GFP without disruption of oocyst egress and salivary gland invasion.
Topics: Animals; Sporozoites; Protozoan Proteins; Anopheles; Oocysts; Plasmodium berghei
PubMed: 38396332
DOI: 10.1111/mmi.15230 -
RSC Medicinal Chemistry Feb 2024The emergence of drug resistance against the frontline antimalarials is a major challenge in the treatment of malaria. In view of emerging reports on drug-resistant...
The emergence of drug resistance against the frontline antimalarials is a major challenge in the treatment of malaria. In view of emerging reports on drug-resistant strains of against artemisinin combination therapy, a dire need is felt for the discovery of novel compounds acting against novel targets in the parasite. In this study, we identified a novel series of quinolinepiperazinyl-aryltetrazoles (QPTs) targeting the blood stage of . anti-plasmodial activity screening revealed that most of the compounds showed IC < 10 μM against chloroquine-resistant INDO strain, with the most promising lead compounds 66 and 75 showing IC values of 2.25 and 1.79 μM, respectively. Further, compounds 64-66, 68, 75-77 and 84 were found to be selective (selectivity index >50) in their action against over a mammalian cell line, with compounds 66 and 75 offering the highest selectivity indexes of 178 and 223, respectively. Explorations into the action of lead compounds 66 and 75 revealed their selective cidal activity towards trophozoites and schizonts. In a ring-stage survival assay, 75 showed cidal activity against the early rings of artemisinin-resistant Cam3.1. Further, 66 and 75 in combination with artemisinin and pyrimethamine showed additive to weak synergistic interactions. Of these two lead molecules, only 66 restricted rise in the percentage of parasitemia to about 10% in -infected mice with a median survival time of 28 days as compared to the untreated control, which showed the percentage of parasitemia >30%, and a median survival of 20 days. Promising antimalarial activity, high selectivity, and additive interaction with artemisinin and pyrimethamine indicate the potential of these compounds to be further optimized chemically as future drug candidates against malaria.
PubMed: 38389888
DOI: 10.1039/d3md00417a -
Malaria Journal Feb 2024The infection of the liver by Plasmodium parasites is an obligatory step leading to malaria disease. Following hepatocyte invasion, parasites differentiate into...
BACKGROUND
The infection of the liver by Plasmodium parasites is an obligatory step leading to malaria disease. Following hepatocyte invasion, parasites differentiate into replicative liver stage schizonts and, in the case of Plasmodium species causing relapsing malaria, into hypnozoites that can lie dormant for extended periods of time before activating. The liver stages of Plasmodium remain elusive because of technical challenges, including low infection rate. This has been hindering experimentations with well-established technologies, such as electron microscopy. A deeper understanding of hypnozoite biology could prove essential in the development of radical cure therapeutics against malaria.
RESULTS
The liver stages of the rodent parasite Plasmodium berghei, causing non-relapsing malaria, and the simian parasite Plasmodium cynomolgi, causing relapsing malaria, were characterized in human Huh7 cells or primary non-human primate hepatocytes using Correlative Light-Electron Microscopy (CLEM). Specifically, CLEM approaches that rely on GFP-expressing parasites (GFP-CLEM) or on an immunofluorescence assay (IFA-CLEM) were used for imaging liver stages. The results from P. berghei showed that host and parasite organelles can be identified and imaged at high resolution using both CLEM approaches. While IFA-CLEM was associated with more pronounced extraction of cellular content, samples' features were generally well preserved. Using IFA-CLEM, a collection of micrographs was acquired for P. cynomolgi liver stage schizonts and hypnozoites, demonstrating the potential of this approach for characterizing the liver stages of Plasmodium species causing relapsing malaria.
CONCLUSIONS
A CLEM approach that does not rely on parasites expressing genetically encoded tags was developed, therefore suitable for imaging the liver stages of Plasmodium species that lack established protocols to perform genetic engineering. This study also provides a dataset that characterizes the ultrastructural features of liver stage schizonts and hypnozoites from the simian parasite species P. cynomolgi.
Topics: Animals; Humans; Parasites; Liver; Malaria; Plasmodium berghei; Microscopy, Electron
PubMed: 38383417
DOI: 10.1186/s12936-024-04862-w