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BioRxiv : the Preprint Server For... May 2024parasite resistance to antimalarial drugs is a serious threat to public health in malaria-endemic areas. Compounds that target core cellular processes like translation...
parasite resistance to antimalarial drugs is a serious threat to public health in malaria-endemic areas. Compounds that target core cellular processes like translation are highly desirable, as they should be multistage actives, capable of killing parasites in the liver and blood, regardless of molecular target or mechanism. Assays that can identify these compounds are thus needed. Recently, specific quantification of native liver stage protein synthesis as well as that of the hepatoma cells supporting parasite growth, was achieved via automated confocal feedback microscopy of the o-propargyl puromycin (OPP)-labeled nascent proteome, but this imaging modality is limited in throughput. Here, we developed and validated a miniaturized high content imaging (HCI) version of the OPP assay that increases throughput, before deploying this approach to screen the Pathogen Box. We identified only two hits, both of which are parasite-specific quinoline-4-carboxamides, and analogues of the clinical candidate and known inhibitor of blood and liver stage protein synthesis, DDD107498/cabamiquine. We further show that these compounds have strikingly distinct relationships between their antiplasmodial and translation inhibition efficacies. These results demonstrate the utility and reliability of the liver stage OPP HCI assay for specific, single-well quantification of and human protein synthesis in the native cellular context, allowing identification of selective translation inhibitors with the highest potential for multistage activity.
PubMed: 38854116
DOI: 10.1101/2024.05.29.596519 -
BioRxiv : the Preprint Server For... May 2024The malaria-causing parasites have to complete a complex infection cycle in the mosquito vector that also involves attack by the insect's innate immune system,...
The malaria-causing parasites have to complete a complex infection cycle in the mosquito vector that also involves attack by the insect's innate immune system, especially at the early stages of midgut infection. However, immunity to the late sporogonic stages, such as oocysts, has received little attention as they are considered to be concealed from immune factors due to their location under the midgut basal lamina and for harboring an elaborate cell wall comprising an external layer derived from the basal lamina that confers self-properties to an otherwise foreign structure. Here, we investigated whether oocysts and sporozoites are susceptible to melanization-based immunity in . Silencing of the negative regulator of melanization response, CLIPA14, increased melanization prevalence without significantly increasing the numbers of melanized oocysts, while co-silencing CLIPA14 with CLIPA2, a second negative regulator of melanization, resulted in a significant increase in melanized oocysts and melanization prevalence. Only late-stage oocysts were found to be melanized, suggesting that oocyst rupture was a prerequisite for melanization-based immune attack, presumably due to the loss of the immune-evasive features of their wall. We also found melanized sporozoites inside oocysts and in the hemocoel, suggesting that sporozoites at different maturation stages are susceptible to melanization. Silencing the melanization promoting factors TEP1 and CLIPA28 rescued oocyst melanization in CLIPA2/CLIPA14 co-silenced mosquitoes. Interestingly, silencing of CTL4, that protects early stage ookinetes from melanization, had no effect on oocysts and sporozoites, indicating differential regulation of immunity to early and late sporogonic stages. Similar to previous studies addressing ookinete stage melanization, the melanization of oocysts was significantly lower than that observed for . In summary, our results provide conclusive evidence that late sporogonic malaria parasite stages are susceptible to melanization, and we reveal distinct regulatory mechanisms for ookinete and oocyst melanization.
PubMed: 38853990
DOI: 10.1101/2024.05.31.596773 -
Parasites, Hosts and Diseases May 2024Malaria is a global disease affecting a large portion of the world's population. Although vaccines have recently become available, their efficacies are suboptimal. We...
Malaria is a global disease affecting a large portion of the world's population. Although vaccines have recently become available, their efficacies are suboptimal. We generated virus-like particles (VLPs) that expressed either apical membrane antigen 1 (AMA1) or microneme-associated antigen (MIC) of Plasmodium berghei and compared their efficacy in BALB/c mice. We found that immune sera acquired from AMA1 VLP- or MIC VLP-immunized mice specifically interacted with the antigen of choice and the whole P. berghei lysate antigen, indicating that the antibodies were highly parasite-specific. Both VLP vaccines significantly enhanced germinal center B cell frequencies in the inguinal lymph nodes of mice compared with the control, but only the mice that received MIC VLPs showed significantly enhanced CD4+ T cell responses in the blood following P. berghei challenge infection. AMA1 and MIC VLPs significantly suppressed TNF-α and interleukin-10 production but had a negligible effect on interferon-γ. Both VLPs prevented excessive parasitemia buildup in immunized mice, although parasite burden reduction induced by MIC VLPs was slightly more effective than that induced by AMA1. Both VLPs were equally effective at preventing body weight loss. Our findings demonstrated that the MIC VLP was an effective inducer of protection against murine experimental malaria and should be the focus of further development.
Topics: Animals; Plasmodium berghei; Mice, Inbred BALB C; Vaccines, Virus-Like Particle; Malaria Vaccines; Malaria; Membrane Proteins; Mice; Protozoan Proteins; Antigens, Protozoan; Female; Antibodies, Protozoan; Parasitemia; CD4-Positive T-Lymphocytes; B-Lymphocytes
PubMed: 38835260
DOI: 10.3347/PHD.24017 -
Journal of Cell Science Jun 2024Plasmodium sporozoites are the infective forms of the malaria parasite in the mosquito and vertebrate host. Gliding motility allows sporozoites to migrate and invade...
Plasmodium sporozoites are the infective forms of the malaria parasite in the mosquito and vertebrate host. Gliding motility allows sporozoites to migrate and invade mosquito salivary glands and mammalian hosts. Motility and invasion are powered by an actin-myosin motor complex linked to the glideosome, which contains glideosome-associated proteins (GAPs), MyoA and the myosin A tail-interacting protein (MTIP). However, the role of several proteins involved in gliding motility remains unknown. We identified that the S14 gene is upregulated in sporozoite from transcriptome data of Plasmodium yoelii and further confirmed its transcription in P. berghei sporozoites using real-time PCR. C-terminal 3×HA-mCherry tagging revealed that S14 is expressed and localized on the inner membrane complex of the sporozoites. We disrupted S14 in P. berghei and demonstrated that it is essential for sporozoite gliding motility, and salivary gland and hepatocyte invasion. The gliding and invasion-deficient S14 knockout sporozoites showed normal expression and organization of inner membrane complex and surface proteins. Taken together, our data show that S14 plays a role in the function of the glideosome and is essential for malaria transmission.
Topics: Sporozoites; Plasmodium berghei; Protozoan Proteins; Animals; Mice; Malaria; Salivary Glands; Anopheles
PubMed: 38832798
DOI: 10.1242/jcs.261857 -
Journal of Experimental Pharmacology 2024Malaria is causing high mortality and morbidity due to resistance to currently available anti-malarial drugs and mosquito's resistance to insecticides. Thus, there is a...
BACKGROUND
Malaria is causing high mortality and morbidity due to resistance to currently available anti-malarial drugs and mosquito's resistance to insecticides. Thus, there is a critical need to search for novel anti-malarial drugs from natural sources. Therefore, this study investigated in vivo antimalarial activities of two Ethiopian medicinal plants, Pax and Thonn, in infected Swiss albino mice.
METHODS
Soxhlet extraction method using 80% methanol as a solvent was used to prepare crude extracts of the two plants. Acute oral toxicity and 4-day suppressive in vivo antimalarial activity tests were performed on healthy female mice and infected male mice, respectively. Antimalarial activity of the crude extracts at doses of 100, 200, and 400 mg/kg and the standard drug, chloroquine were used to assesse in infected Swiss albino mice. Parasitemia level, packed cell volume, body weight, and rectal temperature of the mice were determined before infection (day 0) and after treatment (day 4). Survival time was determined by recording the date on which the mice died, considering the date of infection as day 0. The recorded data were analyzed using ANOVA and SPSS version 24.
RESULTS
The result of the acute toxicity study revealed that the crude extracts were non-toxic at doses up to 2 g/kg. The extract of suppressed parasitemia level by 66.28, 63.44 and 63.14% at 400, 200, and 100mg/kg, levels while extract suppressed parasitemia level by 45.29% at a dose of 400mg/kg. The remaining two dose levels of extract suppressed parasitemia level by < 30%.
CONCLUSION
and showed anti-plasmodial activities. exhibited a more pronounced anti-plasmodial effect than . The activities of both plants observed in this study support their traditional use as antimalarial drugs. Further studies on these plants using solvent fractions are required to identify their active ingredients.
PubMed: 38826847
DOI: 10.2147/JEP.S457659 -
Journal of Ethnopharmacology May 2024Novel drugs are needed to address the issue of malarial infection resistance; natural items can be a different source of these medications. Albizia malacophylla (A....
ETHNOPHARMACOLOGICAL RELEVANCE
Novel drugs are needed to address the issue of malarial infection resistance; natural items can be a different source of these medications. Albizia malacophylla (A. Rich.) Walp. (Leguminosae) is listed as one of the antimalarial medicinal plants in Ethiopian folk medicine. However, there are no reports regarding the biological activity or phytochemistry of the plant.
AIM OF THE STUDY
Thus, this study aimed to evaluate the A. malacophylla crude extract and solvent fractions' in vivo antimalarial activity utilizing 4-day suppressive, preventative, and curative tests in mice infected with P. berghei.
MATERIALS AND METHODS
The parasite Plasmodium berghei, which causes rodent malaria, was used to infect healthy male Swiss Albino mice, weighing 23-28 g and aged 6-8 weeks. Solvent fractions such as methanol, water, and chloroform were given in addition to an 80% methanolic extract at 100, 200, and 400 mg/kg doses. A Conventional test such as parasitemia, survival time, body weight, temperature, and packed cell capacity were employed to ascertain factors such as the suppressive, curative, and preventive tests.
RESULTS
Every test substance dramatically reduced the number of parasites in every experiment. Crude extract (with the highest percentage suppression of 67.78%) performs better antimalarial effect than the methanol fraction, which is the most efficient solvent fraction with a percentage suppression of 55.74%. With a suppression value of 64.83% parasitemia level, the therapeutic effects of 80% methanolic crude extract were greater than its curative and preventative effects in a four-day suppressive test. The survival period (17 days) was longer with the hydroalcoholic crude extract dose of 400 mg/kg than with other doses of the materials under investigation.
CONCLUSIONS
The results of this investigation validate the antimalarial characteristics of A. malacophylla leaf extract. The crude extract prevented weight loss, a decline in temperature, and a reduction in PCV. The results demonstrate that the plant has a promising antimalarial effect against P. berghei, hence supporting the traditional use of the plant. Therefore, it could serve as a foundation for the development of new antimalarial drugs.
PubMed: 38824975
DOI: 10.1016/j.jep.2024.118413 -
Nature Communications Jun 2024Differentiation of male gametocytes into flagellated fertile male gametes relies on the assembly of axoneme, a major component of male development for mosquito...
Differentiation of male gametocytes into flagellated fertile male gametes relies on the assembly of axoneme, a major component of male development for mosquito transmission of the malaria parasite. RNA-binding protein (RBP)-mediated post-transcriptional regulation of mRNA plays important roles in eukaryotic sexual development, including the development of female Plasmodium. However, the role of RBP in defining the Plasmodium male transcriptome and its function in male gametogenesis remains incompletely understood. Here, we performed genome-wide screening for gender-specific RBPs and identified an undescribed male-specific RBP gene Rbpm1 in the Plasmodium. RBPm1 is localized in the nucleus of male gametocytes. RBPm1-deficient parasites fail to assemble the axoneme for male gametogenesis and thus mosquito transmission. RBPm1 interacts with the spliceosome E complex and regulates the splicing initiation of certain introns in a group of 26 axonemal genes. RBPm1 deficiency results in intron retention and protein loss of these axonemal genes. Intron deletion restores axonemal protein expression and partially rectifies axonemal defects in RBPm1-null gametocytes. Further splicing assays in both reporter and endogenous genes exhibit stringent recognition of the axonemal introns by RBPm1. The splicing activator RBPm1 and its target introns constitute an axonemal intron splicing program in the post-transcriptional regulation essential for Plasmodium male development.
Topics: Introns; RNA Splicing; RNA-Binding Proteins; Animals; Protozoan Proteins; Male; Axoneme; Female; Gametogenesis; Spliceosomes; Plasmodium berghei; Malaria; Plasmodium
PubMed: 38824128
DOI: 10.1038/s41467-024-49002-9 -
ACS Infectious Diseases Jun 2024Our previous work identified a series of 12 xanthoquinodin analogues and 2 emodin-dianthrones with broad-spectrum activities against , , , and . Analyses conducted in...
Our previous work identified a series of 12 xanthoquinodin analogues and 2 emodin-dianthrones with broad-spectrum activities against , , , and . Analyses conducted in this study revealed that the most active analogue, xanthoquinodin A1, also inhibits tachyzoites and the liver stage of , with no cross-resistance to the known antimalarial targets PfACS, PfCARL, PfPI4K, or DHODH. In , inhibition occurs prior to multinucleation and induces parasite death following 12 h of compound exposure. This moderately fast activity has impeded resistance line generation, with xanthoquinodin A1 demonstrating an irresistible phenotype in both and .
Topics: Plasmodium falciparum; Antimalarials; Toxoplasma; Drug Resistance; Plasmodium berghei; Animals; Anthraquinones; Humans
PubMed: 38810215
DOI: 10.1021/acsinfecdis.4c00232 -
Narra J Apr 2024In Indonesia, malaria remains a problem, with 94,610 active cases in 2021 and its current therapy includes chloroquine and artemisinin; however, resistance has been...
In Indonesia, malaria remains a problem, with 94,610 active cases in 2021 and its current therapy includes chloroquine and artemisinin; however, resistance has been commonly reported. To overcome this problem, studies about potential medicinal plants that can be used as antimalaria, such as moringa () started to receive more attention. The aim of this study was to investigate the effects of moringa in parasitemia, monocyte activation, and organomegaly on animal model malaria. This experimental study used male , infected by ANKA, as an animal malaria model. The extract was made by maceration of dry moringa leaves, which were then divided into three concentrations: 25%, 50%, and 75%. Dihydroartemisinin-piperazine was used as a positive control treatment, and distilled water as a negative control treatment. The animals were observed for six days to assess the parasitemia count and the number of monocyte activation. On day 7, the animals were terminated, and the liver, spleen, and kidney were weighed. The results showed that the effective concentrations in reducing parasitemia and inducing monocyte activation were 50% and 25% of moringa leaf extract, respectively. The smallest liver and spleen enlargement was observed among animals within the group treated with a 50% concentration of extract. In contrast, the smallest kidney enlargement was observed in the group treated with 25% of extract. Further analysis is recommended to isolate compounds with antimalarial properties in moringa leaves.
Topics: Animals; Mice; Plasmodium berghei; Plant Extracts; Male; Malaria; Monocytes; Parasitemia; Disease Models, Animal; Antimalarials; Moringa; Moringa oleifera; Plant Leaves; Spleen; Organ Size
PubMed: 38798832
DOI: 10.52225/narra.v4i1.653 -
Pathogens (Basel, Switzerland) May 2024The murine model of experimental cerebral malaria (ECM) induced by ANKA was used to investigate the relationship among pro-inflammatory cytokines, alterations in renal...
The murine model of experimental cerebral malaria (ECM) induced by ANKA was used to investigate the relationship among pro-inflammatory cytokines, alterations in renal function biomarkers, and the induction of the TRAIL apoptosis pathway during malaria-associated acute kidney injury (AKI). Renal function was evaluated through the measurement of plasma creatinine and blood urea nitrogen (BUN). The mRNA expression of several cytokines and NaPi-IIa was quantified. Kidney sections were examined and cytokine levels were assessed using cytometric bead array (CBA) assays. The presence of glomerular IgG deposits and apoptosis-related proteins were investigated using in situ immunofluorescence assays and quantitative real-time PCR, respectively. NaPi-IIa downregulation in the kidneys provided novel insights into the pathogenesis of hypophosphatemia during CM. Histopathological analysis revealed characteristic features of severe malaria-associated nephritis, including glomerular collapse and tubular alterations. Pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, were upregulated. The TRAIL apoptosis pathway was significantly activated, implicating its role in renal apoptosis. The observed alterations in renal biomarkers and the downregulation of NaPi-IIa shed light on potential mechanisms contributing to renal dysfunction in ECM. The intricate balance between pro- and anti-inflammatory cytokines, along with the activation of the TRAIL apoptosis pathway, highlights the complexity of malaria-associated AKI and provides new therapeutic targets.
PubMed: 38787228
DOI: 10.3390/pathogens13050376