scholarly journals Febrile temperatures induce cytoadherence of ring-stage Plasmodium falciparum-infected erythrocytes

2002 ◽  
Vol 99 (18) ◽  
pp. 11825-11829 ◽  
Author(s):  
R. Udomsangpetch ◽  
B. Pipitaporn ◽  
K. Silamut ◽  
R. Pinches ◽  
S. Kyes ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Ring Stage

The ring-stage of Plasmodium falciparum observed in RBCs of hospitalized malaria patients

The Analyst ◽  
2015 ◽  
Vol 140 (23) ◽  
pp. 8007-8016 ◽  
Author(s):  
Mateusz Kozicki ◽  
Jacek Czepiel ◽  
Grażyna Biesiada ◽  
Piotr Nowak ◽  
Aleksander Garlicki ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Raman Spectra ◽  
Ring Stage ◽  
Blood Samples

Raman spectra of the blood samples obtained directly from hospitalized malaria patients withPlasmodium falciparum(P. falciparum) in the ring-stage were analyzed.

scholarly journals Tolerance of Gambian Plasmodium falciparum to Dihydroartemisinin and Lumefantrine Detected by Ex Vivo Parasite Survival Rate Assay

2020 ◽  
Vol 65 (1) ◽  
pp. e00720-20
Author(s):  
Haddijatou Mbye ◽  
Fatoumata Bojang ◽  
Aminata Seedy Jawara ◽  
Bekai Njie ◽  
Nuredin Ibrahim Mohammed ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Survival Rate ◽  
Drug Exposure ◽  
Ex Vivo ◽  
Ring Stage ◽  
Color Flow ◽  
Continuous Growth ◽  
Content Type ◽  
Parasite Survival ◽  
Survival Assay

ABSTRACTMonitoring of Plasmodium falciparum sensitivity to antimalarial drugs in Africa is vital for malaria elimination. However, the commonly used ex vivo/in vitro 50% inhibitory concentration (IC50) test gives inconsistent results for several antimalarials, while the alternative ring-stage survival assay (RSA) for artemisinin derivatives has not been widely adopted. Here, we applied an alternative two-color flow cytometry-based parasite survival rate assay (PSRA) to detect ex vivo antimalarial tolerance in P. falciparum isolates from The Gambia. The PSRA infers parasite viability by quantifying reinvasion of uninfected cells following 3 consecutive days of drug exposure (10-fold the IC50 of drug for field isolates). The drug survival rate is obtained for each isolate from the slope of the growth/death curve. We obtained parasite survival rates of 41 isolates for dihydroartemisinin (DHA) and lumefantrine (LUM) out of 51 infections tested by ring-stage survival assay (RSA) against DHA. We also determined the genotypes for known drug resistance genetic loci in the P. falciparum genes Pfdhfr, Pfdhps, Pfmdr, Pfcrt, and Pfk13. The PSRA results determined for 41 Gambian isolates showed faster killing and lower variance after treatment with DHA than after treatment with LUM, despite a strong correlation between the two drugs. Four and three isolates were tolerant to DHA and LUM, respectively, with continuous growth during drug exposure. Isolates with the PfMDR1-Y184F mutant variant showed increased LUM survival, though the results were not statistically significant. Sulfadoxine/pyrimethamine (SP) resistance markers were fixed, while all other antimalarial variants were prevalent in more than 50% of the population. The PSRA detected ex vivo antimalarial tolerance in Gambian P. falciparum. This calls for its wider application and for increased vigilance against resistance to artemisinin combination therapies (ACTs) in this population.

Adhesion of normal and Plasmodium falciparum ring–infected erythrocytes to endothelial cells and the placenta involves the rhoptry-derived ring surface protein-2

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 5025-5032 ◽  
Author(s):  
Jean-Bernard Lekana Douki ◽  
Yvon Sterkers ◽  
Catherine Lépolard ◽  
Boubacar Traoré ◽  
Fabio T. M. Costa ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Plasmodium Falciparum ◽  
Erythrocyte Membrane ◽  
Time Course ◽  
Surface Protein ◽  
Blood Stage ◽  
Current View ◽  
Ring Stage ◽  
Surface Fluorescence ◽  
Falciparum Erythrocyte Membrane Protein

Abstract Recent findings have challenged the current view of Plasmodium falciparum (P falciparum) blood-stage biology by demonstrating the cytoadhesion of early ring-stage–infected erythrocytes (rIEs) to host endothelial cells and placental syncytiotrophoblasts. The adhesion of rIEs was observed only in parasites that bind to the placenta via chondroitin sulfate A (CSA). In this work, a panel of mouse monoclonal antibodies (mAbs) that specifically inhibit cytoadhesion of rIEs but not of mature IEs was generated The previously described ring surface protein 2 (RSP-2), a 42-kDa protein, was identified as the target of the ring-stage–specific mAbs. Time course surface fluorescence experiments revealed a short overlap (approximately 4 hours) of expression between RSP-2 and P falciparum erythrocyte membrane protein 1 (PfEMP1). Their consecutive expression enables IEs to adhere to endothelial cells during the entire blood-stage cycle. During this study, a new phenotype was detected in parasite cultures, the adhesion of normal erythrocytes (nEs) to endothelial cells. All adherent nEs were coated with RSP-2. Immunolocalization studies show that RSP-2 is a rhoptry-derived protein that is discharged onto the erythrocyte membrane during contact with merozoites. Our results identify RSP-2 as a key molecule in sequestration of young blood-stage forms and nEs to endothelial cells.

Cytoadhesion of Plasmodium falciparum ring-stage-infected erythrocytes

10.1038/81374 ◽  
2000 ◽  
Vol 6 (11) ◽  
pp. 1264-1268 ◽  
Author(s):  
B. Pouvelle ◽  
P.A. Buffet ◽  
C. Lépolard ◽  
A. Scherf ◽  
J. Gysin
Keyword(s):  
Plasmodium Falciparum ◽  
Ring Stage

Optimal assay design for determining the in vitro sensitivity of ring stage Plasmodium falciparum to artemisinins

2014 ◽  
Vol 44 (12) ◽  
pp. 893-899 ◽  
Author(s):  
Stanley C. Xie ◽  
Con Dogovski ◽  
Shannon Kenny ◽  
Leann Tilley ◽  
Nectarios Klonis
Keyword(s):  
Plasmodium Falciparum ◽  
Ring Stage ◽  
In Vitro Sensitivity ◽  
Assay Design

A novel Plasmodium falciparum ring stage protein, REX, is located in Maurer’s clefts

2004 ◽  
Vol 136 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Paula L. Hawthorne ◽  
Katharine R. Trenholme ◽  
Tina S. Skinner-Adams ◽  
Tobias Spielmann ◽  
Katja Fischer ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Ring Stage ◽  
Maurer's Clefts

scholarly journals Kelch Mutations in Plasmodium falciparum Protein K13 Do Not Modulate Dormancy after Artemisinin Exposure and Sorbitol Selection In Vitro

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Kimberly F. Breglio ◽  
Rifat S. Rahman ◽  
Juliana M. SÃ ◽  
Amanda Hott ◽  
David J. Roberts ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Single Site ◽  
Ring Stage ◽  
Content Type ◽  
Isogenic Lines ◽  
Falciparum Protein

ABSTRACT Some Kelch mutations of the Plasmodium falciparum K13 protein confer increased survival to dihydroartemisinin (DHA)-treated ring-stage parasites. Here, we asked if K13 mutations affect a dormancy phenotype allowing parasites to survive DHA exposure and then sorbitol selection. Although recrudescence from dormancy differed between two distinct parasite lines, it was similar for isogenic lines carrying single-site substitutions in K13. Therefore, K13 mutations do not alter the DHA-sorbitol combined dormancy phenotype; rather, traits from other loci likely determine this phenotype.

scholarly journals The Plasmodium PI(4)K inhibitor KDU691 selectively inhibits dihydroartemisinin-pretreated Plasmodium falciparum ring-stage parasites

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
L. Dembele ◽  
X. Ang ◽  
M. Chavchich ◽  
G. M. C. Bonamy ◽  
J. J. Selva ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Ring Stage

scholarly journals Plasmodium falciparum Founder Populations in Western Cambodia Have Reduced Artemisinin SensitivityIn Vitro

2014 ◽  
Vol 58 (8) ◽  
pp. 4935-4937 ◽  
Author(s):  
Chanaki Amaratunga ◽  
Benoit Witkowski ◽  
Dalin Dek ◽  
Vorleak Try ◽  
Nimol Khim ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Clearance ◽  
Parasite Development ◽  
Ring Stage ◽  
Content Type ◽  
Short Course ◽  
Founder Populations ◽  
Admixed Population ◽  
Survival Assay

ABSTRACTReducedPlasmodium falciparumsensitivity to short-course artemisinin (ART) monotherapy manifests as a long parasite clearance half-life. We recently defined three parasite founder populations with long half-lives in Pursat, western Cambodia, where reduced ART sensitivity is prevalent. Using the ring-stage survival assay, we show that these founder populations have reduced ART sensitivityin vitroat the early ring stage of parasite development and that a genetically admixed population contains subsets of parasites with normal or reduced ART sensitivity.

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