Stage-dependent production and release of histidine-rich protein 2 by Plasmodium falciparum

Desakorn, Varunee; Dondorp, Arjen M.; Silamut, Kamolrat; Pongtavornpinyo, Wirichada; Sahassananda, Duangjai; Chotivanich, Kesinee; Pitisuttithum, Punnee; Smithyman, Anthony M.; Day, Nicholas P. J.; White, Nicholas J.

doi:10.1016/j.trstmh.2004.11.014

Cited by 100 publications

(106 citation statements)

References 16 publications

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“…2, inset graph). The results are linear across the range of the assay and correspond to an average value of 1.012 fg PfHRP2 per parasite, which is within the range of previously published reports (6).…”

Section: Figsupporting

confidence: 88%

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Enzyme-Linked Immunosorbent Assay for Detection of Plasmodium falciparum Histidine-Rich Protein 2 in Blood, Plasma, and Serum

Kifude

Rajasekariah

Sullivan

et al. 2008

Clin Vaccine Immunol

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Microscopy, the gold standard for the detection and quantification of malaria parasites in blood, is in many aspects deficient for this purpose. The method is poorly reproducible and can be inaccurate because Plasmodium falciparum parasites sequester for a portion of each asexual cycle. Due to these deficiencies, biomarkers such as P. falciparum histidine-rich protein 2 (PfHRP2) are increasingly being used. In this study, we evaluated the use of a commercial PfHRP2 enzyme-linked immunosorbent assay (ELISA) kit with some procedural modifications. We determined the linear range of the assay, including the lower limits of detection and quantitation, using recombinant PfHRP2 (rPfHRP2). In 10 repeat experiments, the linear range of optical densities (ODs) at 450 to 650 nm was from 0.05 ؎ 0.002 to 2.28 ؎ 0.042, corresponding to 3.91 to 250 ng/ml of rPfHRP2. The coefficient of variation (CV) at each target concentration ranged from 1.93 to 8.07%. Using cultured parasites, we confirmed the linear range of ODs as well as the association between the PfHRP2 ELISA results and the microscopic parasite densities. For whole-blood samples spiked with cultured, washed, ring-stage-infected red blood cells (iRBCs), the linear range was 11.7 to 750 iRBCs/l, with CVs of 0.29 to 7.56%. The same spiked samples evaluated by microscopists had similar sensitivities, but the CVs were unacceptably high (20.7 to 161.6%). Stock rPfHRP2 was stable through four freeze-thaw cycles (P < 0.05; paired t test). When different patient sample types at different concentrations within the linear range of the assay are compared, the recoveries of PfHRP2 from blood and serum were within ؎20%, whereas the recoveries from plasma ranged between ؉35 and ؊41%. We conclude that PfHRP2 ELISA using whole-blood and serum samples is a suitable adjunct to microscopy and could ultimately benefit malaria intervention trials.Efficacy assessment of malaria intervention studies still relies on microscopy for quantitation of malaria parasites in blood, despite increasing evidence that its reliability is questionable (1,10,18,21,22). The major attributes of malaria parasite microscopy are its cost effectiveness and simplicity, which in resource-poor countries are important considerations. The major disadvantages of microscopy for Plasmodium falciparum parasite quantitation include poor reproducibility, variable sensitivity, and unacceptably high false-positive rates. In addition, the sequestration of parasites for a portion of each asexual cycle makes mature trophozoite and schizont stages unavailable in the peripheral circulation (9).The parasite biomarkers of choice for quantitative estimates of the burden of infection would be those that are detectable in whole blood or in its separated components, i.e., serum and plasma, irrespective of the location of the parasite. Good candidates are histidine-rich protein 2 (HRP2), found only in P. falciparum, and glycolytic lactate dehydrogenase (LDH) and Plasmodium aldolase, both of which are found in all Plasmodium species (19)....

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Section: Figsupporting

confidence: 88%

“…Although the amount of PfHRP2 released continues to increase throughout the erythrocytic cycle, most of it is released during schizont rupture (6,12). In in vitro assays, the antigen can be detected in culture supernatants of synchronized parasites as early as 2 to 8 hours after ring development (12).…”

mentioning

confidence: 99%

Enzyme-Linked Immunosorbent Assay for Detection of Plasmodium falciparum Histidine-Rich Protein 2 in Blood, Plasma, and Serum

Kifude

Rajasekariah

Sullivan

et al. 2008

Clin Vaccine Immunol

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“…One such protein is the P falciparumspecific histidine-rich protein II (HRPII). 84 Although the specific purpose of HRPII is not well understood, recent studies indicate that it binds glycosaminoglycans (GAGs) with exceptionally high affinity in the presence of zinc or copper ions. 85 Consequently, HRPII-GAG binding significantly impedes GAG-mediated antithrombin inhibition of FXa and thrombin in plasma and reverses the anticoagulant activity of heparin.…”

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confidence: 99%

Emerging roles for hemostatic dysfunction in malaria pathogenesis

O’Sullivan

Preston

O’Regan

et al. 2016

Blood

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Severe Plasmodium falciparum malaria remains a leading cause of mortality, particularly in sub-Saharan Africa where it accounts for up to 1 million deaths per annum. In spite of the significant mortality and morbidity associated with cerebral malaria (CM), the molecular mechanisms involved in the pathophysiology of severe malaria remain surprisingly poorly understood. Previous studies have demonstrated that sequestration of P falciparum–infected erythrocytes within the microvasculature of the brain plays a key role in the development of CM. In addition, there is convincing evidence that both endothelial cell activation and platelets play critical roles in the modulating the pathogenesis of severe P falciparum malaria. In this review, we provide an overview of recent studies that have identified novel roles through which hemostatic dysfunction may directly influence malaria pathogenesis. In particular, we focus on emerging data suggesting that von Willebrand factor, coagulation cascade activation, and dysfunction of the protein C pathway may be of specific importance in this context. These collective insights underscore a growing appreciation of the important, but poorly understood, role of hemostatic dysfunction in malaria progression and, importantly, illuminate potential approaches for novel therapeutic strategies. Given that the mortality rate associated with CM remains on the order of 20% despite the availability of effective antimalarial therapy, development of adjunctive therapies that can attenuate CM progression clearly represents a major unmet need. These emerging data are thus not only of basic scientific interest, but also of direct clinical significance.

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“…13 Histidine-rich protein 2 is specific for P. falciparum , yet there is variability in HRP-2 among different P. falciparum strains, with some strains lacking HRP-2.…”

Section: Principles Of Hrp-2 and Pldhmentioning

confidence: 99%

Rapid Malaria Tests: Where Do We Go After 20 Years?

Makler¹,

Piper²

2009

The American Journal of Tropical Medicine and Hygiene

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Abstract. Great advances have been made in developing rapid diagnostic tests (RDTs) for diagnosing malaria. To date, RDTs present an exceedingly practical format for malaria diagnosis that outperforms traditional microscopy and more experimental next generation devices in the development pipeline. However, although use of such tests is accepted in principle, their actual use has lagged. Furthermore, study of how these tests perform, what their limitations are, and how to work with these limitations to still use them effectively has stagnated. We propose that the study and implementation of such RDTs should be aggressively advanced and propose a series of questions that can guide efforts.

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Stage-dependent production and release of histidine-rich protein 2 by Plasmodium falciparum

Cited by 100 publications

References 16 publications

Enzyme-Linked Immunosorbent Assay for Detection of Plasmodium falciparum Histidine-Rich Protein 2 in Blood, Plasma, and Serum

Enzyme-Linked Immunosorbent Assay for Detection of Plasmodium falciparum Histidine-Rich Protein 2 in Blood, Plasma, and Serum

Emerging roles for hemostatic dysfunction in malaria pathogenesis

Rapid Malaria Tests: Where Do We Go After 20 Years?

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