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Journal of Vector Borne Diseases 2019The alarming failure in malaria treatment using conventional drugs calls for urgent search of alternatives; one of which is to exploit natural products such as plants....
BACKGROUND & OBJECTIVES
The alarming failure in malaria treatment using conventional drugs calls for urgent search of alternatives; one of which is to exploit natural products such as plants. This study evaluated the effects of three selected commercial herbal preparations on albino mice infected with Plasmodium berghei NK65, a lethal strain of rodent malaria.
METHODS
This study was conducted in the University of Nigeria, Nsukka between February and September 2017. A total of 30 adult albino mice were randomized into six groups of five mice each. Group 1 served as normal control. Mice in Groups 2-6 were parasitized with P. berghei. Group 2 mice were untreated while mice in Groups 3, 4, 5 and 6 were treated with 20 mg/kg body weight of artesunate; and 5 ml/kg body weight of the seleceted commercial herbal preparations designated as HA, HB and HC, respectively. The percent malaria parasitaemia, haematological parameters, lipid profile, liver function markers, antioxidant status and lipid peroxidation index were evaluated using standard protocol.
RESULTS
It was observed that mice in Group 2 had significantly higher percentage of malaria parasitaemia when compared to mice in parasitized and treated groups. Also, haematological dysfunctions, dyslipidaemia, oxidative stress and hepatotoxicity seen in parasitized and untreated mice were restored in parasitized and artesunate- and herbal preparations-treated mice.
INTERPRETATION & CONCLUSION
Findings from the present study revealed that oxidative stress, characterized by low antioxidant status and high lipid peroxidation, contributes to complications in malaria. The results also indicate that the studied commercial herbal preparations possess good antimalarial and ameliorative effects on malaria-induced haematological, lipid, antioxidant and liver aberrations in mice. The acute toxicity profiles of the commercial herbal preparations suggested that they are tolerable and safe at the doses administered.
Topics: Albinism; Animals; Antimalarials; Artesunate; Lipid Peroxidation; Liver; Mice; Oxidative Stress; Parasitemia; Plant Extracts; Plant Leaves; Plasmodium berghei
PubMed: 31397390
DOI: 10.4103/0972-9062.263722 -
Parasites & Vectors Jul 2021Plasmodium sp., which causes malaria, must first develop in mosquitoes before being transmitted. Upon ingesting infected blood, gametes form in the mosquito lumen,...
BACKGROUND
Plasmodium sp., which causes malaria, must first develop in mosquitoes before being transmitted. Upon ingesting infected blood, gametes form in the mosquito lumen, followed by fertilization and differentiation of the resulting zygotes into motile ookinetes. Within 24 h of blood ingestion, these ookinetes traverse mosquito epithelial cells and lodge below the midgut basal lamina, where they differentiate into sessile oocysts that are protected by a capsule.
METHODS
We identified an ookinete surface and oocyst capsule protein (OSCP) that is involved in ookinete motility as well as oocyst capsule formation.
RESULTS
We found that knockout of OSCP in parasite decreases ookinete gliding motility and gradually reduces the number of oocysts. On day 15 after blood ingestion, the oocyst wall was significantly thinner. Moreover, adding anti-OSCP antibodies decreased the gliding speed of wild-type ookinetes in vitro. Adding anti-OSCP antibodies to an infected blood meal also resulted in decreased oocyst formation.
CONCLUSION
These findings may be useful for the development of a transmission-blocking tool for malaria.
Topics: Animals; Antibodies, Protozoan; Culicidae; Female; Malaria; Male; Mice; Mice, Inbred BALB C; Microscopy, Electron, Transmission; Mosquito Vectors; Oocysts; Plasmodium berghei; Protozoan Proteins
PubMed: 34289894
DOI: 10.1186/s13071-021-04868-2 -
PloS One 2013Plasmodium Calcium Dependent Protein Kinase (CDPK1) is required for the development of sexual stages in the mosquito. In addition, it is proposed to play an essential...
Plasmodium Calcium Dependent Protein Kinase (CDPK1) is required for the development of sexual stages in the mosquito. In addition, it is proposed to play an essential role in the parasite's invasive stages possibly through the regulation of the actinomyosin motor and micronemal secretion. We demonstrate that Plasmodium berghei CDPK1 is dispensable in the parasite's erythrocytic and pre-erythrocytic stages. We successfully disrupted P. berghei CDPK1 (PbCDPK1) by homologous recombination. The recovery of erythrocytic stage parasites lacking PbCDPK1 (PbCDPK1-) demonstrated that PbCDPK1 is not essential for erythrocytic invasion or intra-erythrocytic development. To study PbCDPK1's role in sporozoites and liver stage parasites, we generated a conditional mutant (CDPK1 cKO). Phenotypic characterization of CDPK1 cKO sporozoites demonstrated that CDPK1 is redundant or dispensable for the invasion of mammalian hepatocytes, the egress of parasites from infected hepatocytes and through the subsequent erythrocytic cycle. We conclude that P. berghei CDPK1 plays an essential role only in the mosquito sexual stages.
Topics: Animals; Anopheles; Erythrocytes; Gene Knockout Techniques; Hep G2 Cells; Host-Parasite Interactions; Humans; Life Cycle Stages; Plasmodium berghei; Protein Kinases
PubMed: 24265753
DOI: 10.1371/journal.pone.0079171 -
Molecular and Biochemical Parasitology Oct 2014T-protein, an aminomethyltransferase, represents one of the four components of glycine cleavage system (GCS) and catalyzes the transfer of methylene group from H-protein...
T-protein, an aminomethyltransferase, represents one of the four components of glycine cleavage system (GCS) and catalyzes the transfer of methylene group from H-protein intermediate to tetrahydrofolate (THF) forming N(5), N(10)-methylene THF (CH2-THF) with the release of ammonia. The malaria parasite genome encodes T-, H- and L-proteins, but not P-protein which is a glycine decarboxylase generating the aminomethylene group. A putative GCS has been considered to be functional in the parasite mitochondrion despite the absence of a detectable P-protein homologue. In the present study, the mitochondrial localization of T-protein in the malaria parasite was confirmed by immunofluorescence and its essentiality in the entire parasite life cycle was studied by targeting the T-protein locus in Plasmodium berghei (Pb). PbT knock out parasites did not show any growth defect in asexual, sexual and liver stages indicating that the T-protein is dispensable for parasite survival in vertebrate and invertebrate hosts. The absence of P-protein homologue and the non-essentiality of T protein suggest the possible redundancy of GCS activity in the malaria parasite. Nevertheless, the H- and L-proteins of GCS could be essential for malaria parasite because of their involvement in α-ketoacid dehydrogenase reactions.
Topics: Aminomethyltransferase; Animals; Gene Knockout Techniques; Gene Targeting; Genes, Essential; Life Cycle Stages; Mice; Phenotype; Plasmodium berghei; Protein Transport
PubMed: 25454081
DOI: 10.1016/j.molbiopara.2014.10.003 -
Antimicrobial Agents and Chemotherapy May 2016Glutathione plays a central role in maintaining cellular redox homeostasis, and modulations to this status may affect malaria parasite sensitivity to certain types of...
Glutathione plays a central role in maintaining cellular redox homeostasis, and modulations to this status may affect malaria parasite sensitivity to certain types of antimalarials. In this study, we demonstrate that inhibition of glutathione biosynthesis in the Plasmodium berghei ANKA strain through disruption of the γ-glutamylcysteine synthetase (γ-GCS) gene, which encodes the first and rate-limiting enzyme in the glutathione biosynthetic pathway, significantly sensitizes parasites in vivo to pyrimethamine and sulfadoxine, but not to chloroquine, artesunate, or primaquine, compared with control parasites containing the same pyrimethamine-resistant marker cassette. Treatment of mice infected with an antifolate-resistant P. berghei control line with a γ-GCS inhibitor, buthionine sulfoximine, could partially abrogate pyrimethamine and sulfadoxine resistance. The role of glutathione in modulating the malaria parasite's response to antifolates suggests that development of specific inhibitors against Plasmodium γ-GCS may offer a new approach to counter Plasmodium antifolate resistance.
Topics: Animals; Antimalarials; Artemisinins; Artesunate; Chloroquine; Drug Resistance; Female; Glutamate-Cysteine Ligase; Glutathione; Malaria; Mice; Mice, Inbred BALB C; Plasmodium berghei; Pyrimethamine; Sulfadoxine
PubMed: 26953195
DOI: 10.1128/AAC.01836-15 -
Cellular Microbiology May 2014Calcium is a key signalling molecule in apicomplexan parasites and plays an important role in diverse processes including gliding motility. Gliding is essential for the...
Calcium is a key signalling molecule in apicomplexan parasites and plays an important role in diverse processes including gliding motility. Gliding is essential for the malaria parasite to migrate from the skin to the liver as well as to invade host tissues and cells. Here we investigated the dynamics of intracellular Ca(2+) in the motility of Plasmodium berghei sporozoites by live imaging and flow cytometry. We found that cytosolic levels of Ca(2+) increase when sporozoites are activated in suspension, which is sufficient to induce the secretion of integrin-like adhesins that are essential for gliding motility. By increasing intracellular Ca(2+) levels artificially with an ionophore, these adhesins are secreted onto the sporozoite surface, however, the parasite is not capable of gliding. A second level of Ca(2+) modulation was observed during attachment to and detachment from a solid substrate, leading to a further increase or a decrease in the cytoplasmic levels of Ca(2+) respectively. We also observed oscillations in the intracellular Ca(2+) level during gliding. Finally, an intracellular Ca(2+) chelator, an inhibitor of phosphoinositide-specific phospholipase C (PI-PLC), and an inhibitor of the inositol triphosphate (IP3) receptor blocked the rise in intracellular Ca(2+) , adhesin secretion, and motility of activated sporozoites, indicating that intracellular stores supply Ca(2+) during sporozoite gliding. Our study indicates that a rise in intracellular Ca(2+) is necessary but not sufficient to activate gliding, that Ca(2+) levels are modulated in several ways during motility, and that a PI-PLC/IP3 pathway regulates Ca(2+) release during the process of sporozoite locomotion.
Topics: Calcium; Cell Adhesion; Cytosol; Flow Cytometry; Locomotion; Optical Imaging; Plasmodium berghei; Sporozoites
PubMed: 24617597
DOI: 10.1111/cmi.12289 -
Experimental Parasitology Jan 1999Amplification, mutations, or overexpression of the pfmdr1 gene have been associated with multiple drug resistance in some strains of Plasmodium falciparum. In order to...
Amplification, mutations, or overexpression of the pfmdr1 gene have been associated with multiple drug resistance in some strains of Plasmodium falciparum. In order to better understand this potential mechanism of drug resistance, we are currently investigating putative mdr homologues in vivo in the rodent malaria Plasmodium berghei. We have identified and partially sequenced a gene that is amplified in a MFQ-resistant (MFQr) line. Using degenerate primers, a 579-bp fragment was amplified by PCR using P. berghei genomic DNA as template. The predicted amino acid sequence shares 66% identity with the previously reported pfmdr1 gene product (Pgh1) of P. falciparum. Southern blots and slot blots of genomic DNA suggest that this gene is amplified two- to threefold in a MFQr line (N/1100), as has been previously reported in some MFQr strains of P. falciparum. The P. berghei gene was mapped to chromosome 12 in all of the lines analyzed. Furthermore, the cloned PCR product also hybridizes to chromosome 5 of the MFQr strain.
Topics: ATP-Binding Cassette Transporters; Amino Acid Sequence; Animals; Antimalarials; Chromosome Mapping; Cloning, Molecular; Drug Resistance, Multiple; Gene Amplification; Gene Dosage; Genes, Protozoan; Mefloquine; Molecular Sequence Data; Plasmodium berghei; Polymerase Chain Reaction; Protozoan Proteins; Sequence Alignment
PubMed: 9920046
DOI: 10.1006/expr.1999.4344 -
Parasites & Vectors Jan 2017Plasmodium ookinete surface proteins as post-fertilization target antigens are potential malaria transmission-blocking vaccine (TBV) candidates. Putative secreted...
BACKGROUND
Plasmodium ookinete surface proteins as post-fertilization target antigens are potential malaria transmission-blocking vaccine (TBV) candidates. Putative secreted ookinete protein 25 (PSOP25) is a highly conserved ookinete surface protein, and has been shown to be a promising novel TBV target. Here, we further investigated the TBV activities of the full-length recombinant PSOP25 (rPSOP25) protein in Plasmodium berghei, and characterized the potential functions of PSOP25 during the P. berghei life-cycle.
METHODS
We expressed the full-length P. berghei PSOP25 protein in a prokaryotic expression system, and developed polyclonal mouse antisera and a monoclonal antibody (mAb) against the recombinant protein. Indirect immunofluorescence assay (IFA) and Western blot were used to test the specificity of antibodies. The transmission-blocking (TB) activities of antibodies were evaluated by the in vitro ookinete conversion assay and by direct mosquito feeding assay (DFA). Finally, the function of PSOP25 during Plasmodium development was studied by deleting the psop25 gene.
RESULTS
Both polyclonal mouse antisera and anti-rPSOP25 mAb recognized the PSOP25 proteins in the parasites, and IFA showed the preferential expression of PSOP25 on the surface of zygotes, retorts and mature ookinetes. In vitro, these antibodies significantly inhibited ookinetes formation in an antibody concentration-dependent manner. In DFA, mice immunized with the rPSOP25 and those receiving passive transfer of the anti-rPSOP25 mAb reduced the prevalence of mosquito infection by 31.2 and 26.1%, and oocyst density by 66.3 and 63.3%, respectively. Genetic knockout of the psop25 gene did not have a detectable impact on the asexual growth of P. berghei, but significantly affected the maturation of ookinetes and the formation of midgut oocysts.
CONCLUSIONS
The full-length rPSOP25 could elicit strong antibody response in mice. Polyclonal and monoclonal antibodies against PSOP25 could effectively block the formation of ookinetes in vitro and transmission of the parasites to mosquitoes. Genetic manipulation study indicated that PSOP25 is required for ookinete maturation in P. berghei. These results support further testing of the PSOP25 orthologs in human malaria parasites as promising TBV candidates.
Topics: Animals; Antibodies, Protozoan; Antigens, Protozoan; Disease Models, Animal; Disease Transmission, Infectious; Gene Deletion; Immunization, Passive; Malaria; Malaria Vaccines; Mice; Plasmodium berghei; Protozoan Proteins
PubMed: 28057055
DOI: 10.1186/s13071-016-1932-4 -
Cellular Microbiology Apr 2015Plasmodium spp., which causes malaria, produces a histamine-releasing factor (HRF), an orthologue of mammalian HRF. Histamine-releasing factor produced by erythrocytic...
Plasmodium spp., which causes malaria, produces a histamine-releasing factor (HRF), an orthologue of mammalian HRF. Histamine-releasing factor produced by erythrocytic stages of the parasite is thought to play a role in the pathogenesis of severe malaria. Here, we show in a rodent model that HRF is not important during the erythrocytic but pre-erythrocytic phase of infection, which mainly consists in the transformation in the liver of the mosquito-injected parasite form into the erythrocyte-infecting form. Development of P. berghei ANKA cl15cy1 liver stages lacking HRF is impaired and associated with an early rise in systemic IL-6, a cytokine that strongly suppresses development of Plasmodium liver stages. The defect is rescued by injection of anti-IL-6 antibodies or infection in IL-6-deficient mice and parasite HRF is sufficient to decrease IL-6 synthesis, indicating a direct role of parasite HRF in reducing host IL-6. The target cells modulated by HRF for IL-6 production at early time points during liver infection are neutrophils. Parasite HRF is thus used to down-regulate a cytokine with anti-parasite activity. Our data also highlight the link between a prolonged transition from liver to blood-stage infection and reduced incidence of experimental cerebral malaria.
Topics: Animals; Biomarkers, Tumor; Disease Models, Animal; Host-Pathogen Interactions; Interleukin-6; Liver; Malaria; Mice; Mice, Knockout; Plasmodium berghei; Treatment Outcome; Tumor Protein, Translationally-Controlled 1
PubMed: 25329441
DOI: 10.1111/cmi.12382 -
Pathogens and Global Health May 2023sporozoites associated with the midgut and in the hemolymph of mosquitoes differ from sporozoites in the secretory cavities and ducts of the insects' salivary glands in...
sporozoites associated with the midgut and in the hemolymph of mosquitoes differ from sporozoites in the secretory cavities and ducts of the insects' salivary glands in their transcriptome, proteome, motility, and infectivity. Using an salivary gland culture system incorporating simple microfluidics and transgenic with the fluorescent protein gene under the transcriptional control of the promoter whose expression served as a proxy for parasite maturation, we observed rapid parasite maturation in the absence of salivary gland invasion. While expression was only detectable in sporozoites within the salivary glands (mature parasites) as expected, the simple exposure of sporozoites to dissected salivary glands led to rapid parasite maturation as indicated by mCherry expression. These results suggest that previous efforts to develop and systems for investigating sporozoite interactions with mosquito salivary glands have likely been unsuccessful in part because the maturation of sporozoites leads to a loss in the ability to invade salivary glands.
Topics: Animals; Anopheles; Plasmodium berghei; Sporozoites; Gene Expression Regulation; Salivary Glands
PubMed: 35993325
DOI: 10.1080/20477724.2022.2108647