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Parasitology International Feb 2023Malaria is a life-threatening disease caused by infection with Plasmodium parasites. The goal of developing an effective malaria vaccine is yet to be reached despite...
Malaria is a life-threatening disease caused by infection with Plasmodium parasites. The goal of developing an effective malaria vaccine is yet to be reached despite decades of massive research efforts. CD4 helper T cells, CD8 cytotoxic T cells, and γδ T cells are associated with immune responses to both liver-stage and blood-stage Plasmodium infection. The immune responses of T cell-lineages to Plasmodium infection are associated with both protection and immunopathology. Studies with mouse model of malaria contribute to our understanding of host immune response. In this paper, we focus primarily on mouse malaria model with blood-stage Plasmodium berghei infection and review our knowledge of T cell immune responses against Plasmodium infection. Moreover, we also discuss findings of experimental human studies. Uncovering the precise mechanisms of T cell-mediated immunity to Plasmodium infection can be accomplished through further investigations using mouse models of malaria with rodent Plasmodium parasites. Those findings would be invaluable to advance the efforts for development of an effective malaria vaccine.
Topics: Humans; Animals; Mice; Plasmodium berghei; T-Lymphocytes; Malaria Vaccines; Malaria; Immunity, Cellular; Disease Models, Animal
PubMed: 35998816
DOI: 10.1016/j.parint.2022.102646 -
Mammalian Genome : Official Journal of... Aug 2018Malaria is a common and sometimes fatal disease caused by infection with Plasmodium parasites. Cerebral malaria (CM) is a most severe complication of infection with... (Review)
Review
Malaria is a common and sometimes fatal disease caused by infection with Plasmodium parasites. Cerebral malaria (CM) is a most severe complication of infection with Plasmodium falciparum parasites which features a complex immunopathology that includes a prominent neuroinflammation. The experimental mouse model of cerebral malaria (ECM) induced by infection with Plasmodium berghei ANKA has been used abundantly to study the role of single genes, proteins and pathways in the pathogenesis of CM, including a possible contribution to neuroinflammation. In this review, we discuss the Plasmodium berghei ANKA infection model to study human CM, and we provide a summary of all host genetic effects (mapped loci, single genes) whose role in CM pathogenesis has been assessed in this model. Taken together, the reviewed studies document the many aspects of the immune system that are required for pathological inflammation in ECM, but also identify novel avenues for potential therapeutic intervention in CM and in diseases which feature neuroinflammation.
Topics: Animals; Disease Models, Animal; Humans; Malaria, Cerebral; Mice; Plasmodium berghei
PubMed: 29922917
DOI: 10.1007/s00335-018-9752-9 -
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 -
Phytotherapy Research : PTR Sep 2018Due to the challenges in the control, prevention, and eradication of parasitic diseases like malaria, there is an urgent need to discover new therapeutic agents....
Due to the challenges in the control, prevention, and eradication of parasitic diseases like malaria, there is an urgent need to discover new therapeutic agents. Plant-derived medicines may open new ways in the field of antiplasmodial therapy. This study is aimed to investigate the toxicity and in vivo antiplasmodial activity of apigenin, a dietary flavonoid. Apigenin cytotoxicity was investigated on Huh7 cell line, brine shrimp (Artemia salina) larva, and human red blood cells. In vivo toxicity of apigenin was assessed by metabolomics approaches. Apigenin exhibited significant suppression of parasitemia in a dose-dependent manner; it suppressed Plasmodium berghei growth by 69.74%, 50.3%, and 49.23% at concentrations of 70, 35, and 15 mg/kg/day, respectively. The IC value for apigenin after 24 hr exposure to Huh7 cells was 225 μg/ml. Apigenin did not show noticeable toxicity on A. salina and also on the membrane integrity of red blood cells. After 24 hr exposure of mice to apigenin, alterations were seen in the metabolism of glucocorticoids and mineralocorticoids, bile acid metabolism (alternative pathway), sulfur metabolism, bile acid metabolism, metabolism of estrogens and androgens, cholesterol catabolism, and biosynthesis of cholesterol. These findings indicate that apigenin has potential in vivo antiplasmodial activity against P. berghei infected mice with high selectivity against malaria, but it can disrupt some metabolic pathways in mice.
Topics: Animals; Antimalarials; Apigenin; Artemia; Cell Line; Erythrocytes; Humans; Malaria; Male; Metabolic Networks and Pathways; Metabolome; Mice; Plants, Medicinal; Plasmodium berghei; Toxicity Tests
PubMed: 29748995
DOI: 10.1002/ptr.6113 -
Infection and Immunity Jan 2023In the acidic lysosome-like digestive vacuole, parasites crystallize heme from hemoglobin into hemozoin, or malaria pigment. Upon release of progeny merozoites, the...
In the acidic lysosome-like digestive vacuole, parasites crystallize heme from hemoglobin into hemozoin, or malaria pigment. Upon release of progeny merozoites, the residual hemozoin is phagocytized by macrophages principally in the liver and spleen where the heme crystals can persist for months to years, as heme oxygenase does not readily degrade the crystal. Previous studies demonstrated hemozoin modulation of monocytes and macrophages. Hemozoin modulates immune function activity of monocytes/macrophages. Here, we used purified/washed hemozoin (W-Hz) isolated from murine Plasmodium berghei infections and intravenously (i.v.) injected it back into naive mice. We characterized the modulating effect of W-Hz on liver-stage replication. Purified washed hemozoin decreases P. berghei liver levels both at 1 week and 1 month after i.v. injection in a dose and time dependent fashion. The injected hemozoin fully protected in nine out of 10 mice given a 50 sporozoite inoculum, and in 10 out of 10 mice against 2,000 sporozoites when they were infected an hour or a day after hemozoin inoculation. DNase treatment at the hemozoin reversed the observed liver load reduction. The liver load reduction was similar in mature B- and T-cell-deficient RAG-1 knockout (KO) mice suggesting an innate immune protection mechanism. This work indicates a role for residual hemozoin in down modulation of liver stages.
Topics: Mice; Animals; Malaria; Mice, Inbred BALB C; Plasmodium berghei; Sporozoites; Liver; Heme; DNA
PubMed: 36622216
DOI: 10.1128/iai.00304-22 -
Emerging Microbes & Infections Dec 2022The family of apicomplexan specific proteins contains caspases-like proteins called "metacaspases". These enzymes are present in the malaria parasite but absent in...
The family of apicomplexan specific proteins contains caspases-like proteins called "metacaspases". These enzymes are present in the malaria parasite but absent in human; therefore, these can be explored as potential drug targets. We deleted the MCA-2 gene from genome using a gene knockout strategy to decipher its precise function. This study has identified that MCA-2 plays an important role in parasite transmission since it is critical for the formation of gametocytes and for maintaining an appropriate number of infectious sporozoites required for sporogony. It is noticeable that a significant reduction in gametocyte, oocysts, ookinete and sporozoites load along with a delay in hepatocytes invasion were observed in the MCA-2 knockout parasite. Furthermore, a study found the two MCA-2 inhibitory molecules known as C-532 and C-533, which remarkably inhibited the MCA-2 activity, abolished the parasite growth, and also impaired the transmission cycle of and in . Our findings indicate that the deletion of MCA-2 hampers the development during erythrocytic and exo-erythrocytic stages, and its inhibition by C-532 and C-533 critically affects the malaria transmission biology.
Topics: Animals; Gametogenesis; Humans; Malaria; Plasmodium berghei; Protozoan Proteins; Sporozoites
PubMed: 35264080
DOI: 10.1080/22221751.2022.2052357 -
Pathogens and Global Health Mar 2015Plasmodium berghei was identified as a parasite of thicket rats (Grammomys dolichurus) and Anopheles dureni mosquitoes in African highland forests. Successful adaptation... (Review)
Review
Plasmodium berghei was identified as a parasite of thicket rats (Grammomys dolichurus) and Anopheles dureni mosquitoes in African highland forests. Successful adaptation to a range of rodent and mosquito species established P. berghei as a malaria model parasite. The introduction of stable transfection technology, permitted classical reverse genetics strategies and thus systematic functional profiling of the gene repertoire. In the past 10 years following the publication of the P. berghei genome sequence, many new tools for experimental genetics approaches have been developed and existing ones have been improved. The infection of mice is the principal limitation towards a genome-wide repository of mutant parasite lines. In the past few years, there have been some promising and most welcome developments that allow rapid selection and isolation of recombinant parasites while simultaneously minimising animal usage. Here, we provide an overview of all the currently available tools and methods.
Topics: Animals; Anopheles; Disease Models, Animal; Genetic Vectors; Genome-Wide Association Study; Host-Parasite Interactions; Life Cycle Stages; Malaria; Mice; Molecular Sequence Data; Organisms, Genetically Modified; Plasmodium berghei; Rats; Transfection
PubMed: 25789828
DOI: 10.1179/2047773215Y.0000000006 -
Malaria Journal Feb 2021Evidence of Plasmodium resistance to some of the current anti-malarial agents makes it imperative to search for newer and effective drugs to combat malaria. Therefore,...
BACKGROUND
Evidence of Plasmodium resistance to some of the current anti-malarial agents makes it imperative to search for newer and effective drugs to combat malaria. Therefore, this study evaluated whether the co-administrations of xylopic acid-amodiaquine and xylopic acid-artesunate combinations will produce a synergistic anti-malarial effect.
METHODS
Antiplasmodial effect of xylopic acid (XA: 3, 10, 30, 100, 150 mg kg), artesunate (ART: 1, 2, 4, 8, 16 mg kg), and amodiaquine (AQ: 1.25, 2.5, 5, 10, 20 mg kg) were evaluated in Plasmodium berghei (strain ANKA)-infected mice to determine respective EDs. Artemether/lumefantrine was used as the positive control. XA/ART and XA/AQ were subsequently administered in a fixed-dose combination of their EDs (1:1) and the combination fractions of their EDs (1/2, 1/4, 1/8, 1/16, and 1/32) to determine the experimental EDs (Z). An isobologram was constructed to determine the nature of the interaction between XA/ART, and XA/AQ combinations by comparing Z with the theoretical ED (Z). Bodyweight and 30-day survival post-treatment were additionally recorded.
RESULTS
EDs for XA, ART, and AQ were 9.0 ± 3.2, 1.61 ± 0.6, and 3.1 ± 0.8 mg kg, respectively. The Z, Z and interaction index for XA/ART co-administration was 5.3 ± 2.61, 1.98 ± 0.25, and 0.37, respectively while that of XA/AQ were 6.05 ± 2.0, 1.69 ± 0.42, and 0.28, respectively. The Z for both combination therapies lay significantly (p < 0.001) below the additive isoboles showing XA acts synergistically with both ART and AQ in clearing the parasites. High doses of XA/ART combination significantly (p < 0.05) increased the survival days of infected mice with a mean hazard ratio of 0.40 while all the XA/AQ combination doses showed a significant (p < 0.05) increase in the survival days of infected mice with a mean hazard ratio of 0.27 similar to AL. Both XA/ART and XA/AQ combined treatments significantly (p < 0.05) reduced weight loss.
CONCLUSION
Xylopic acid co-administration with either artesunate or amodiaquine produces a synergistic anti-plasmodial effect in mice infected with P. berghei.
Topics: Amodiaquine; Animals; Antimalarials; Artesunate; Diterpenes, Kaurane; Dose-Response Relationship, Drug; Drug Combinations; Female; Malaria; Mice; Mice, Inbred ICR; Plasmodium berghei
PubMed: 33632233
DOI: 10.1186/s12936-021-03658-6 -
Nucleic Acids Research Jan 2020The lack of endogenous RNAi machinery in the malaria parasite Plasmodium hampers gene annotation and hence antimalarial drug and vaccine development. Here, we engineered...
The lack of endogenous RNAi machinery in the malaria parasite Plasmodium hampers gene annotation and hence antimalarial drug and vaccine development. Here, we engineered rodent Plasmodium berghei to express a minimal, non-canonical RNAi machinery that solely requires Argonaute 2 (Ago2) and a modified short hairpin RNA, so-called AgoshRNA. Using this strategy, we achieved robust and specific gene knockdown throughout the entire parasite life cycle. We also successfully silenced the endogenous gene perforin-like protein 2, phenocopying a full gene knockout. Transcriptionally restricting Ago2 expression to the liver stage further enabled us to perform a stage-specific gene knockout. The RNAi-competent Plasmodium lines reported here will be a valuable resource for loss-of-function phenotyping of the many uncharacterized genes of Plasmodium in low or high throughput, without the need to engineer the target gene locus. Thereby, our new strategy and transgenic Plasmodium lines will ultimately benefit the discovery of urgently needed antimalarial drug and vaccine candidates. Generally, the ability to render RNAi-negative organisms RNAi-competent by mere introduction of two components, Ago2 and AgoshRNA, is a unique paradigm that should find broad applicability in other species.
Topics: Animals; Anopheles; Argonaute Proteins; Female; Genes, Reporter; Genetic Engineering; Green Fluorescent Proteins; Life Cycle Stages; Mice; Mice, Inbred C57BL; Mosquito Vectors; Organisms, Genetically Modified; Perforin; Plasmodium berghei; Protozoan Proteins; RNA Interference; RNA, Small Interfering; Transgenes
PubMed: 31680162
DOI: 10.1093/nar/gkz927 -
Molecular Microbiology Jul 2016Multidrug resistance (MDR) proteins belong to the B subfamily of the ATP Binding Cassette (ABC) transporters, which export a wide range of compounds including...
Multidrug resistance (MDR) proteins belong to the B subfamily of the ATP Binding Cassette (ABC) transporters, which export a wide range of compounds including pharmaceuticals. In this study, we used reverse genetics to study the role of all seven Plasmodium MDR proteins during the life cycle of malaria parasites. Four P. berghei genes (encoding MDR1, 4, 6 and 7) were refractory to deletion, indicating a vital role during blood stage multiplication and validating them as potential targets for antimalarial drugs. Mutants lacking expression of MDR2, MDR3 and MDR5 were generated in both P. berghei and P. falciparum, indicating a dispensable role for blood stage development. Whereas P. berghei mutants lacking MDR3 and MDR5 had a reduced blood stage multiplication in vivo, blood stage growth of P. falciparum mutants in vitro was not significantly different. Oocyst maturation and sporozoite formation in Plasmodium mutants lacking MDR2 or MDR5 was reduced. Sporozoites of these P. berghei mutants were capable of infecting mice and life cycle completion, indicating the absence of vital roles during liver stage development. Our results demonstrate vital and dispensable roles of MDR proteins during blood stages and an important function in sporogony for MDR2 and MDR5 in both Plasmodium species.
Topics: Animals; Antimalarials; Culicidae; Drug Resistance, Multiple; Female; Life Cycle Stages; Malaria; Malaria, Falciparum; Male; Membrane Transport Proteins; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Multidrug Resistance-Associated Proteins; Oocytes; Plasmodium berghei; Plasmodium falciparum; Sporozoites
PubMed: 26991313
DOI: 10.1111/mmi.13373