scholarly journals Function and essentiality of Plasmodium falciparum plasmepsin V

2018 ◽  
Author(s):  
Nonlawat Boonyalai ◽  
Christine R. Collins ◽  
Fiona Hackett ◽  
Chrislaine Withers-Martinez ◽  
Michael J. Blackman
Keyword(s):  
Plasmodium Falciparum ◽  
Gene Disruption ◽  
Clinical Malaria ◽  
Protein Export ◽  
Growth Defect ◽  
Phenotypic Analysis ◽  
Adhesive Properties ◽  
Erythrocytic Cycle ◽  
Severe Growth Defect ◽  
Gene Excision

AbstractThe malaria parasite replicates within erythrocytes. The pathogenesis of clinical malaria is in large part due to the capacity of the parasite to remodel its host cell. To do this, intraerythrocytic stages of Plasmodium falciparum export more than 300 proteins that dramatically alter the morphology of the infected erythrocyte as well as its mechanical and adhesive properties. P. falciparum plasmepsin V (PfPMV) is an aspartic protease that processes proteins for export into the host erythrocyte and is thought to play a key role in parasite virulence and survival. However, although standard techniques for gene disruption as well as conditional protein knockdown have been previously attempted with the pfpmv gene, complete gene removal or knockdown was not achieved so direct genetic proof that PMV is an essential protein has not yet been established. Here we have used a conditional gene excision approach combining CRISPR-Cas9 gene editing and DiCre-mediated recombination to functionally inactivate the pfpmv gene. The resulting mutant parasites displayed a severe growth defect. Detailed phenotypic analysis showed that development of the mutant parasites was arrested at the ring-to-trophozoite transition in the erythrocytic cycle following gene excision, likely due to a defect in protein export. Our findings are the first to elucidate the effects of PMV gene disruption, showing that it is essential for parasite viability in asexual blood stages. The mutant parasites can now be used as a platform to further dissect the Plasmodium protein export pathway.

DDB1 gene disruption causes a severe growth defect and apoptosis in chicken DT40 cells

2007 ◽  
Vol 364 (4) ◽  
pp. 771-777 ◽  
Author(s):  
Mitsuo Wakasugi ◽  
Kenkyo Matsuura ◽  
Atsushi Nagasawa ◽  
DongTao Fu ◽  
Hiroko Shimizu ◽  
...  
Keyword(s):  
Gene Disruption ◽  
Growth Defect ◽  
Severe Growth Defect ◽  
Dt40 Cells ◽  
Severe Growth

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

scholarly journals Changes in Antigen-Specific Cytokine and Chemokine Responses to Plasmodium falciparum Antigens in a Highland Area of Kenya after a Prolonged Absence of Malaria Exposure

2014 ◽  
Vol 82 (9) ◽  
pp. 3775-3782 ◽  
Author(s):  
Lyticia A. Ochola ◽  
Cyrus Ayieko ◽  
Lily Kisia ◽  
Ng'wena G. Magak ◽  
Estela Shabani ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Severe Disease ◽  
Clinical Malaria ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Highland Area ◽  
Cytokine Responses ◽  
Increased Risk ◽  
Tnf Α ◽  
Ifn Γ

ABSTRACTIndividuals naturally exposed toPlasmodium falciparumlose clinical immunity after a prolonged lack of exposure.P. falciparumantigen-specific cytokine responses have been associated with protection from clinical malaria, but the longevity ofP. falciparumantigen-specific cytokine responses in the absence of exposure is not well characterized. A highland area of Kenya with low and unstable malaria transmission provided an opportunity to study this question. The levels of antigen-specific cytokines and chemokines associated in previous studies with protection from clinical malaria (gamma interferon [IFN-γ], interleukin-10 [IL-10], and tumor necrosis factor alpha [TNF-α]), with increased risk of clinical malaria (IL-6), or with pathogenesis of severe disease in malaria (IL-5 and RANTES) were assessed by cytometric bead assay in April 2008, October 2008, and April 2009 in 100 children and adults. During the 1-year study period, none had an episode of clinicalP. falciparummalaria. Two patterns of cytokine responses emerged, with some variation by antigen: a decrease at 6 months (IFN-γ and IL-5) or at both 6 and 12 months (IL-10 and TNF-α) or no change over time (IL-6 and RANTES). These findings document thatP. falciparumantigen-specific cytokine responses associated in prior studies with protection from malaria (IFN-γ, TNF-α, and IL-10) decrease significantly in the absence ofP. falciparumexposure, whereas those associated with increased risk of malaria (IL-6) do not. The study findings provide a strong rationale for future studies of antigen-specific IFN-γ, TNF-α, and IL-10 responses as biomarkers of increased population-level susceptibility to malaria after prolonged lack ofP. falciparumexposure.

scholarly journals Treatment of Chronic Asymptomatic Plasmodium falciparum Infection Does Not Increase the Risk of Clinical Malaria Upon Reinfection

2016 ◽  
Vol 64 (5) ◽  
pp. 645-653 ◽  
Author(s):  
Silvia Portugal ◽  
Tuan M. Tran ◽  
Aissata Ongoiba ◽  
Aboudramane Bathily ◽  
Shanping Li ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clinical Malaria ◽  
Falciparum Infection ◽  
Plasmodium Falciparum Infection

scholarly journals Knockdown of the translocon protein EXP2 in Plasmodium falciparum reduces growth and protein export

PLoS ONE ◽  
2018 ◽  
Vol 13 (11) ◽  
pp. e0204785 ◽  
Author(s):  
Sarah C. Charnaud ◽  
Rasika Kumarasingha ◽  
Hayley E. Bullen ◽  
Brendan S. Crabb ◽  
Paul R. Gilson
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Export

scholarly journals Overexpression of Plasmodium falciparum M1 Aminopeptidase Promotes an Increase in Intracellular Proteolysis and Modifies the Asexual Erythrocytic Cycle Development

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1452
Author(s):  
Carolina C. Hoff ◽  
Mauro F. Azevedo ◽  
Adriana B. Thurler ◽  
Sarah El Chamy Maluf ◽  
Pollyana M. S. Melo ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Fold Increase ◽  
Cysteine Proteases ◽  
Aminopeptidase Activity ◽  
Lower Sensitivity ◽  
Wild Type ◽  
Erythrocytic Cycle ◽  
Transgenic Parasite

Plasmodium falciparum, the most virulent of the human malaria parasite, is responsible for high mortality rates worldwide. We studied the M1 alanyl-aminopeptidase of this protozoan (PfA-M1), which is involved in the final stages of hemoglobin cleavage, an essential process for parasite survival. Aiming to help in the rational development of drugs against this target, we developed a new strain of P. falciparum overexpressing PfA-M1 without the signal peptide (overPfA-M1). The overPfA-M1 parasites showed a 2.5-fold increase in proteolytic activity toward the fluorogenic substrate alanyl-7-amido-4-methylcoumarin, in relation to the wild-type group. Inhibition studies showed that overPfA-M1 presented a lower sensitivity against the metalloaminopeptidase inhibitor bestatin and to other recombinant PfA-M1 inhibitors, in comparison with the wild-type strain, indicating that PfA-M1 is a target for the in vitro antimalarial activity of these compounds. Moreover, overPfA-M1 parasites present a decreased in vitro growth, showing a reduced number of merozoites per schizont, and also a decrease in the iRBC area occupied by the parasite in trophozoite and schizont forms when compared to the controls. Interestingly, the transgenic parasite displays an increase in the aminopeptidase activity toward Met-, Ala-, Leu- and Arg-7-amido-4-methylcoumarin. We also investigated the potential role of calmodulin and cysteine proteases in PfA-M1 activity. Taken together, our data show that the overexpression of PfA-M1 in the parasite cytosol can be a suitable tool for the screening of antimalarials in specific high-throughput assays and may be used for the identification of intracellular molecular partners that modulate their activity in P. falciparum.

scholarly journals PfAP2-EXP2, an Essential Transcription Factor for the Intraerythrocytic Development of Plasmodium falciparum

2022 ◽  
Vol 9 ◽  
Author(s):  
Xiaomin Shang ◽  
Changhong Wang ◽  
Li Shen ◽  
Fei Sheng ◽  
Xiaohui He ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Transcription Factor ◽  
Dna Sequences ◽  
Transcriptome Profiling ◽  
Growth Defect ◽  
Developmental Cycle ◽  
Appreciable Effect ◽  
Expression Of Genes ◽  
Cell Remodeling ◽  
New Perspective

Plasmodium falciparum undergoes a series of asexual replications in human erythrocytes after infection, which are effective targets for combatting malaria. Here, we report roles of an ApiAP2 transcription factor PfAP2-EXP2 (PF3D7_0611200) in the intraerythrocytic developmental cycle of P. falciparum. PfAP2-EXP2 conditional knockdown resulted in an asexual growth defect but without an appreciable effect on parasite morphology. Further ChIP-seq analysis revealed that PfAP2-EXP2 targeted genes related to virulence and interaction between erythrocytes and parasites. Especially, PfAP2-EXP2 regulation of euchromatic genes does not depend on recognizing specific DNA sequences, while a CCCTAAACCC motif is found in its heterochromatic binding sites. Combined with transcriptome profiling, we suggest that PfAP2-EXP2 is participated in the intraerythrocytic development by affecting the expression of genes related to cell remodeling at the schizont stage. In summary, this study explores an ApiAP2 member plays an important role for the P. falciparum blood-stage replication, which suggests a new perspective for malaria elimination.

scholarly journals Gene Disruption of Plasmodium falciparum p52 Results in Attenuation of Malaria Liver Stage Development in Cultured Primary Human Hepatocytes

PLoS ONE ◽  
2008 ◽  
Vol 3 (10) ◽  
pp. e3549 ◽  
Author(s):  
Ben C. L. van Schaijk ◽  
Chris J. Janse ◽  
Geert-Jan van Gemert ◽  
Melissa R. van Dijk ◽  
Audrey Gego ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Gene Disruption ◽  
Human Hepatocytes ◽  
Liver Stage ◽  
Primary Human Hepatocytes ◽  
Stage Development
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