Characterisation of Plasmodium falciparum RESA-like protein peptides that bind specifically to erythrocytes and inhibit invasion

2007 ◽  
Vol 388 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Luis Eduardo Rodriguez ◽  
Ricardo Vera ◽  
John Valbuena ◽  
Hernando Curtidor ◽  
Javier Garcia ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Surface ◽  
Binding Assays ◽  
Gene Encoding ◽  
Trophozoite Stage ◽  
Rbc Membrane ◽  
Erythrocyte Invasion ◽  
Erythrocyte Surface ◽  
Maurer's Clefts

Abstract The Plasmodium falciparum ring-erythrocyte surface antigen (RESA)-like putative protein was identified and characterised. PCR and RT-PCR assays revealed that the gene encoding this protein was both present and being transcribed in P. falciparum strain FCB-2 16 h after erythrocyte invasion. Indirect immunofluorescence studies detected this protein in infected erythrocyte (IE) cytosol in dense fluorescent granules similar to Maurer's clefts at 16–20 h (parasites in ring and trophozoite stages) and very strongly on IE membranes at 22 h, suggesting that it is synthesised during early ring stages (16 h) and transported to the infected red blood cell (RBC) membrane surface during the trophozoite stage (22 h). Western blotting showed that antisera produced against polymerised synthetic peptides of this protein recognised a 72-kDa band in P. falciparum schizont lysate. P. falciparum RESA-like peptides used in normal RBC binding assays revealed that peptides 30326 (101NAEKI LGFDD KNILE ALDLFY120), 30334 (281RVTWK KLRTK MIKAL KKSLTY300) and 30342 (431SSPQR LKFTA GGGFC GKLRNY450) bind with high activity and saturability, presenting nM affinity constants. These peptides contain α-helical structural elements, as determined by circular dichroism, and inhibit P. falciparum in vitro invasion of normal RBCs by up to 91%, suggesting that some RESA-like protein regions are involved in intra-erythrocyte stage P. falciparum invasion.

scholarly journals A new method for the capture of surface proteins in Plasmodium falciparum parasitized erythrocyte

2012 ◽  
Vol 6 (06) ◽  
pp. 536-541 ◽  
Author(s):  
Emanuela Ferru ◽  
Anntonella Pantaleo ◽  
Francesco Turrini
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Surface ◽  
Electrophoretic Analysis ◽  
Cytoskeletal Proteins ◽  
Surface Proteins ◽  
New Method ◽  
Major Drawback ◽  
Rbc Membrane ◽  
Wide Range ◽  
Erythrocyte Surface

Introduction: We propose a new method for the selective labeling, isolation and electrophoretic analysis of the Plasmodium falciparum protein exposed on the erythrocyte cell surface. Historically, membrane surface proteins have been isolated using a surface biotinylation followed by capture of biotin-conjugated protein via an avidin/streptavidin-coated solid support. The major drawback of the standard methods has been the labeling of internal proteins due to fast internalization of biotin. Methodology: To solve this problem, we used a biotin label that does not permeate through the membrane. As a further precaution to avoid the purification of non surface exposed proteins, we directly challenged whole labeled cells with avidin coated beads and then solubilized them using non ionic detergents. Results: A marked enrichment of most of the RBC membrane proteins known to face the external surface of the membrane validated the specificity of the method; furthermore, only small amounts of haemoglobin and cytoskeletal proteins were detected. A wide range of P. falciparum proteins were additionally described to be exposed on the erythrocyte surface. Some of them have been previously observed and used as vaccine candidates while a number of newly described antigens have been presently identified. Those antigens require further characterization and validation with additional methods. Conclusion: Surface proteins preparations were very reproducible and identification of proteins by mass spectrometry has been demonstrated to be feasible and effective.

scholarly journals Plasmodium falciparum Line-Dependent Association ofIn VitroGrowth-Inhibitory Activity and Risk of Malaria

2012 ◽  
Vol 80 (5) ◽  
pp. 1900-1908 ◽  
Author(s):  
Josea Rono ◽  
Anna Färnert ◽  
Daniel Olsson ◽  
Faith Osier ◽  
Ingegerd Rooth ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Inhibitory Activity ◽  
Content Type ◽  
Phenotypic Differences ◽  
Erythrocyte Invasion ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Control Study

ABSTRACTPlasmodium falciparum's ability to invade erythrocytes is essential for its survival within the human host. Immune mechanisms that impair this ability are therefore expected to contribute to immunity against the parasite. Plasma of humans who are naturally exposed to malaria has been shown to have growth-inhibitory activity (GIA)in vitro. However, the importance of GIA in relation to protection from malaria has been unclear. In a case-control study nested within a longitudinally followed population in Tanzania, plasma samples collected at baseline from 171 individuals (55 cases and 116 age-matched controls) were assayed for GIA using threeP. falciparumlines (3D7, K1, and W2mef) chosen based on their erythrocyte invasion phenotypes. Distribution of GIA differed between the lines, with most samples inhibiting the growth of 3D7 and K1 and enhancing the growth of W2mef. GIA to 3D7 was associated with a reduced risk of malaria within 40 weeks of follow-up (odds ratio, 0.45; 95% confidence interval [CI], 0.21 to 0.96;P= 0.04), whereas GIA to K1 and W2mef was not. These results show that GIA, as well as its association with protection from malaria, is dependent on theP. falciparumline and can be explained by differences in erythrocyte invasion phenotypes between parasite lines. Our study contributes knowledge on the biological importance of growth inhibition and the potential influence ofP. falciparumerythrocyte invasion phenotypic differences on its relationship to protective immunity against malaria.

scholarly journals Strain-Dependent Inhibition of Erythrocyte Invasion by Monoclonal Antibodies Against Plasmodium falciparum CyRPA

2021 ◽  
Vol 12 ◽  
Author(s):  
Anne S. Knudsen ◽  
Kasper H. Björnsson ◽  
Maria R. Bassi ◽  
Melanie R. Walker ◽  
Andreas Kok ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Monoclonal Antibodies ◽  
Protective Antigen ◽  
Blood Stage ◽  
Merozoite Invasion ◽  
Interacting Protein ◽  
Erythrocyte Invasion ◽  
Dependent Inhibition ◽  
Strain Dependent

The highly conserved Plasmodium falciparum cysteine-rich protective antigen (PfCyRPA) is a key target for next-generation vaccines against blood-stage malaria. PfCyRPA constitute the core of a ternary complex, including the reticulocyte binding-like homologous protein 5 (PfRh5) and the Rh5-interacting protein (PfRipr), and is fundamental for merozoite invasion of erythrocytes. In this study, we show that monoclonal antibodies (mAbs) specific to PfCyRPA neutralize the in vitro growth of Ghanaian field isolates as well as numerous laboratory-adapted parasite lines. We identified subsets of mAbs with neutralizing activity that bind to distinct sites on PfCyRPA and that in combination potentiate the neutralizing effect. As antibody responses against multiple merozoite invasion proteins are thought to improve the efficacy of blood-stage vaccines, we also demonstrated that combinations of PfCyRPA- and PfRh5 specific mAbs act synergistically to neutralize parasite growth. Yet, we identified prominent strain-dependent neutralization potencies, which our results suggest is independent of PfCyRPA expression level and polymorphism, demonstrating the importance of addressing functional converseness when evaluating blood-stage vaccine candidates. Finally, our results suggest that blood-stage vaccine efficacy can be improved by directing the antibody response towards defined protective epitopes on multiple parasite antigens.

scholarly journals Cyclic di-GMP Positively Regulates DNA Repair in Vibrio cholerae

2018 ◽  
Vol 200 (15) ◽  
Author(s):  
Nicolas L. Fernandez ◽  
Disha Srivastava ◽  
Amanda L. Ngouajio ◽  
Christopher M. Waters
Keyword(s):  
Dna Repair ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Binding Assays ◽  
Gene Encoding ◽  
Repair Gene ◽  
Content Type ◽  
Dna Repair Gene ◽  
High Concentrations

ABSTRACT In Vibrio cholerae, high intracellular cyclic di-GMP (c-di-GMP) concentration are associated with a biofilm lifestyle, while low intracellular c-di-GMP concentrations are associated with a motile lifestyle. c-di-GMP also regulates other behaviors, such as acetoin production and type II secretion; however, the extent of phenotypes regulated by c-di-GMP is not fully understood. We recently determined that the sequence upstream of the DNA repair gene encoding 3-methyladenine glycosylase (tag) was positively induced by c-di-GMP, suggesting that this signaling system might impact DNA repair pathways. We identified a DNA region upstream of tag that is required for transcriptional induction by c-di-GMP. We further showed that c-di-GMP induction of tag expression was dependent on the c-di-GMP-dependent biofilm regulators VpsT and VpsR. In vitro binding assays and heterologous host expression studies show that VpsT acts directly at the tag promoter in response to c-di-GMP to induce tag expression. Last, we determined that strains with high c-di-GMP concentrations are more tolerant of the DNA-damaging agent methyl methanesulfonate. Our results indicate that the regulatory network of c-di-GMP in V. cholerae extends beyond biofilm formation and motility to regulate DNA repair through the VpsR/VpsT c-di-GMP-dependent cascade. IMPORTANCE Vibrio cholerae is a prominent human pathogen that is currently causing a pandemic outbreak in Haiti, Yemen, and Ethiopia. The second messenger molecule cyclic di-GMP (c-di-GMP) mediates the transitions in V. cholerae between a sessile biofilm-forming state and a motile lifestyle, both of which are important during V. cholerae environmental persistence and human infections. Here, we report that in V. cholerae c-di-GMP also controls DNA repair. We elucidate the regulatory pathway by which c-di-GMP increases DNA repair, allowing this bacterium to tolerate high concentrations of mutagens at high intracellular levels of c-di-GMP. Our work suggests that DNA repair and biofilm formation may be linked in V. cholerae.

scholarly journals Functional Analysis of the Exported Type IV HSP40 Protein PfGECO in Plasmodium falciparum Gametocytes

2011 ◽  
Vol 10 (11) ◽  
pp. 1492-1503 ◽  
Author(s):  
Belinda J. Morahan ◽  
Carolyn Strobel ◽  
Uzma Hasan ◽  
Beata Czesny ◽  
Pierre-Yves Mantel ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Heat Shock ◽  
Protective Role ◽  
Targeted Disruption ◽  
Content Type ◽  
Type Iv ◽  
Rbc Membrane ◽  
Host Defense Response ◽  
Hsp40 Protein

ABSTRACTDuringPlasmodium falciparuminfection, host red blood cell (RBC) remodeling is required for the parasite's survival. Such modifications are mediated by the export of parasite proteins into the RBC that alter the architecture of the RBC membrane and enable cytoadherence. It is probable that some exported proteins also play a protective role against the host defense response. This may be of particular importance for the gametocyte stage of the life cycle that is responsible for malaria transmission, since the gametocyte remains in contact with blood as it proceeds through five morphological stages (I to V) during its 12-day maturation. Using microarray analysis, we identified several genes with encoded secretory or export sequences that were differentially expressed during early gametocytogenesis. One of these,PfGECO, encodes a predicted type IV heat shock protein 40 (HSP40) that we show is expressed in gametocyte stages I to IV and is exported to the RBC cytoplasm. HSPs are traditionally induced under stressful conditions to maintain homeostasis, butPfGECOexpression was not increased upon heat shock, suggesting an alternate function. Targeted disruption ofPfGECOindicated that the gene is not essential for gametocytogenesisin vitro, and quantitative reverse transcriptase PCR (RT-PCR) showed that there was no compensatory expression of the other type IV HSP40 genes. AlthoughP. falciparumHSP40 members are implicated in the trafficking of proteins to the RBC surface, removal of PfGECO did not affect the targeting of other exported gametocyte proteins. This work has expanded the repertoire of known gametocyte-exported proteins to include a type IV HSP40, PfGECO.

scholarly journals In Vitro Activity of Pyronaridine against Multidrug-Resistant Plasmodium falciparum and Plasmodium vivax

2010 ◽  
Vol 54 (12) ◽  
pp. 5146-5150 ◽  
Author(s):  
R. N. Price ◽  
J. Marfurt ◽  
F. Chalfein ◽  
E. Kenangalem ◽  
K. A. Piera ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Combination Therapy ◽  
Plasmodium Vivax ◽  
Artemisinin Combination Therapy ◽  
Rank Correlation ◽  
Multidrug Resistant ◽  
Trophozoite Stage ◽  
Nm Range

ABSTRACT Pyronaridine, a Mannich base antimalarial, has demonstrated high in vivo and in vitro efficacy against chloroquine-resistant Plasmodium falciparum. Although this drug has the potential to become a prominent artemisinin combination therapy, little is known about its efficacy against drug-resistant Plasmodium vivax. The in vitro antimalarial susceptibility of pyronaridine was assessed in multidrug-resistant P. vivax (n = 99) and P. falciparum (n = 90) isolates from Papua, Indonesia, using a schizont maturation assay. The median 50% inhibitory concentration (IC50) of pyronaridine was 1.92 nM (range, 0.24 to 13.8 nM) against P. falciparum and 2.58 nM (range, 0.13 to 43.6 nM) against P. vivax, with in vitro susceptibility correlating significantly with chloroquine, amodiaquine, and piperaquine (rs [Spearman's rank correlation coefficient] = 0.45 to 0.62; P < 0.001). P. falciparum parasites initially at trophozoite stage had higher IC50s of pyronaridine than those exposed at the ring stage (8.9 nM [range, 0.6 to 8.9 nM] versus 1.6 nM [range, 0.6 to 8.9 nM], respectively; P = 0.015), although this did not reach significance for P. vivax (4.7 nM [range, 1.4 to 18.7 nM] versus 2.5 nM [range, 1.4 to 15.6 nM], respectively; P = 0.085). The excellent in vitro efficacy of pyronaridine against both chloroquine-resistant P. vivax and P. falciparum highlights the suitability of the drug as a novel partner for artemisinin-based combination therapy in regions where the two species are coendemic.

Aberrant development of Plasmodium falciparum in hemoglobin CC red cells: implications for the malaria protective effect of the homozygous state

Blood ◽  
2003 ◽  
Vol 101 (8) ◽  
pp. 3309-3315 ◽  
Author(s):  
Rick M. Fairhurst ◽  
Hisashi Fujioka ◽  
Karen Hayton ◽  
Kathleen F. Collins ◽  
Thomas E. Wellems
Keyword(s):  
Plasmodium Falciparum ◽  
Epidemiologic Studies ◽  
Red Cells ◽  
Replication Capacity ◽  
Multiplication Rate ◽  
Hemoglobin C ◽  
Erythrocyte Surface ◽  
Parasite Multiplication ◽  
Parasite Replication

Abstract Although selection of hemoglobin C (HbC) by malaria has been speculated for decades, only recently have epidemiologic studies provided support for HbC protection against malaria in West Africa. A reduced risk of malaria associated with the homozygous CC state has been attributed to the inability of CC cells to support parasite multiplication in vitro. However, there have been conflicting data and conclusions regarding the ability of CC red cells to support parasite replication. Reports that parasites cannot multiply in CC cells in vitro contrast with detection of substantial parasite densities in CC patients with malaria. We have therefore investigated Plasmodium falciparum growth in CC cells in vitro. Our data show that the multiplication rate of several P falciparum lines is measurable in CC cells, but lower than that in AA (HbA-normal) cells. A high proportion of ring forms and trophozoites disintegrates within a subset of CC cells, an observation that accounts for the overall lower replication rate. In addition, knobs present on the surface of infected CC cells are fewer in number and morphologically aberrant when compared with those on AA cells. Events in malaria pathogenesis that involve remodeling of the erythrocyte surface and the display of parasite antigens may be affected by these knob abnormalities. Our data suggest that only a subset of CC cells supports normal parasite replication and that components of malaria protection associated with the CC state may affect the parasite's replication capacity and involve aberrant knob formation on CC cells.

scholarly journals Delivery of the Malaria Virulence Protein PfEMP1 to the Erythrocyte Surface Requires Cholesterol-Rich Domains

2006 ◽  
Vol 5 (5) ◽  
pp. 849-860 ◽  
Author(s):  
Sarah Frankland ◽  
Akinola Adisa ◽  
Paul Horrocks ◽  
Theodore F. Taraschi ◽  
Timothy Schneider ◽  
...  
Keyword(s):  
Erythrocyte Membrane ◽  
Infected Erythrocyte ◽  
Membrane Microdomains ◽  
Human Malaria Parasite ◽  
Vesicle Budding ◽  
Erythrocyte Invasion ◽  
Major Virulence Factor ◽  
Erythrocyte Surface ◽  
Virulence Protein ◽  
Maurer's Clefts

ABSTRACT The particular virulence of the human malaria parasite Plasmodium falciparum derives from export of parasite-encoded proteins to the surface of the mature erythrocytes in which it resides. The mechanisms and machinery for the export of proteins to the erythrocyte membrane are largely unknown. In other eukaryotic cells, cholesterol-rich membrane microdomains or “rafts” have been shown to play an important role in the export of proteins to the cell surface. Our data suggest that depletion of cholesterol from the erythrocyte membrane with methyl-β-cyclodextrin significantly inhibits the delivery of the major virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). The trafficking defect appears to lie at the level of transfer of PfEMP1 from parasite-derived membranous structures within the infected erythrocyte cytoplasm, known as the Maurer's clefts, to the erythrocyte membrane. Thus our data suggest that delivery of this key cytoadherence-mediating protein to the host erythrocyte membrane involves insertion of PfEMP1 at cholesterol-rich microdomains. GTP-dependent vesicle budding and fusion events are also involved in many trafficking processes. To determine whether GTP-dependent events are involved in PfEMP1 trafficking, we have incorporated non-membrane-permeating GTP analogs inside resealed erythrocytes. Although these nonhydrolyzable GTP analogs reduced erythrocyte invasion efficiency and partially retarded growth of the intracellular parasite, they appeared to have little direct effect on PfEMP1 trafficking.

scholarly journals Plasmodium falciparum-infected erythrocyte receptor(s) for CD36 and thrombospondin are restricted to knobs on the erythrocyte surface.

1992 ◽  
Vol 40 (9) ◽  
pp. 1419-1422 ◽  
Author(s):  
K Nakamura ◽  
T Hasler ◽  
K Morehead ◽  
R J Howard ◽  
M Aikawa
Keyword(s):  
Endothelial Cells ◽  
Plasmodium Falciparum ◽  
Cerebral Malaria ◽  
Vascular Occlusion ◽  
Cerebral Microvessels ◽  
Erythrocyte Surface ◽  
Infected Rbcs ◽  
First Time

Adherence of Plasmodium falciparum-infected RBCs (PRBC) to endothelial cells causes PRBC sequestration in cerebral microvessels and is considered to be a major contributor to the pathogenesis of cerebral malaria. Both CD36 and thrombospondin (TSP) are glycoproteins that mediate PRBC adherence to endothelial cells in vitro. Because they are both expressed on the surface of endothelial cells, they probably contribute to PRBC sequestration and vascular occlusion in vivo. By applying affinity labeling of receptor binding sites with purified ligands, we showed for the first time that both CD36 and TSP can bind independently to the PRBC surface and that the PRBC receptor(s) for CD36 and TSP are localized specifically to the electron-dense knob protrusions of the PRBC surface. These findings may help in efforts to develop a malaria vaccine to prevent cerebral malaria.

scholarly journals Novel Antimalarial Aminoquinolines: Heme Binding and Effects on Normal or Plasmodium falciparum-Parasitized Human Erythrocytes

2009 ◽  
Vol 53 (10) ◽  
pp. 4339-4344 ◽  
Author(s):  
Fausta Omodeo-Salè ◽  
Lucia Cortelezzi ◽  
Nicoletta Basilico ◽  
Manolo Casagrande ◽  
Anna Sparatore ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Heme Binding ◽  
Human Red Blood Cells ◽  
Rbc Membrane ◽  
Alkyl Derivatives ◽  
Resistant Strains ◽  
Dose Dependent

ABSTRACT Two new quinolizidinyl-alkyl derivatives of 7-chloro-4-aminoquinoline, named AM-1 and AP4b, which are highly effective in vitro against both the D10 (chloroquine [CQ] susceptible) and W2 (CQ resistant) strains of Plasmodium falciparum and in vivo in the rodent malaria model, have been studied for their ability to bind to and be internalized by normal or parasitized human red blood cells (RBC) and for their effects on RBC membrane stability. In addition, an analysis of the heme binding properties of these compounds and of their ability to inhibit beta-hematin formation in vitro has been performed. Binding of AM1 or AP4b to RBC is rapid, dose dependent, and linearly related to RBC density. Their accumulation in parasitized RBC (pRBC) is increased twofold compared to levels in normal RBC. Binding of AM1 or AP4b to both normal and pRBC is higher than that of CQ, in agreement with the lower pKa and higher lipophilicity of the compounds. AM1 or AP4b is not hemolytic per se and is less hemolytic than CQ when hemolysis is accelerated (induced) by hematin. Moreover, AM-1 and AP4b bind heme with a stoichiometry of interaction similar to that of CQ (about 1:1.7) but with a lower affinity. They both inhibit dose dependently the formation of beta-hematin in vitro with a 50% inhibitory concentration comparable to that of CQ. Taken together, these results suggest that the antimalarial activity of AM1 or AP4b is likely due to inhibition of hemozoin formation and that the efficacy of these compounds against the CQ-resistant strains can be ascribed to their hydrophobicity and capacity to accumulate in the vacuolar lipid (elevated lipid accumulation ratios).

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