Complete in vitro maturation of Plasmodium falciparum gametocytes

Ifediba, Titus; Vanderberg, Jerome P.

doi:10.1038/294364a0

Cited by 288 publications

(175 citation statements)

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“…falciparum parasites. P. falciparum strain 3D7 parasites were maintained in culture, and gametocytogenesis was induced as described by Ifediba and Vanderberg (13). Cultures containing mature stage V gametocytes were incubated at 37°C in complete RPMI 1640 (Invitrogen, Carlsbad, CA) for the indicated time with or without protease inhibitors, 100 M E64d (Sigma, St Louis, MO), 10 M YA29 (generously provided by M. Bogyo and D. Greenbaum) (10), and 10 M morpholine urea-leucine-homophenylalanine-phenolvinylsulfone (Mu-Leu-hPheVSPh) and 10 M morpholine urea-leucine-homophenylalanine-fluoromethylketone (Mu-Leu-hPhe-FMK) (generously provided by P. Rosenthal) (29).…”

Section: Methodsmentioning

confidence: 99%

Inhibition of Plasmodium falciparum Oocyst Production by Membrane-Permeant Cysteine Protease Inhibitor E64d

Ekşi

Czesny

Gemert³

et al. 2007

Antimicrob Agents Chemother

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During asexual intraerythrocytic growth, Plasmodium falciparum utilizes hemoglobin obtained from the host red blood cell (RBC) as a nutrient source. Papain-like cysteine proteases, falcipains 2 and 3, have been reported to be involved in hemoglobin digestion and are targets of current antimalarial drug development efforts. However, their expression during gametocytogenesis, which is required for malaria parasite transmission, has not been studied. Many of the available antimalarials do not inhibit development of sexual stage parasites, and therefore, the persistence of gametocytes after drug treatment allows continued transmission of the disease. In the work reported here, incubation of stage V gametocytes with membrane-permeant cysteine protease inhibitor E64d significantly inhibited oocyst production (80 to 100%). The same conditions inhibited processing of gametocyte-surface antigen Pfs230 during gametogenesis but did not alter the morphology of the food vacuole in gametocytes, inhibit emergence, or block male exflagellation. E64d reduced the level of oocyst production more effectively than that reported previously for falcipain 1-knockout parasites, suggesting that falcipains 2 and 3 may also be involved in malaria parasite transmission. However, in this study only falcipain 3 and not falcipain 2 was found to be expressed in stage V gametocytes. Interestingly, during gametocytogenesis falcipain 3 was transported into the red blood cell and by stage V was localized in vesicles along the RBC surface, consistent with a role during gamete emergence. The ability of a membrane-permeant cysteine protease inhibitor to significantly reduce malaria parasite transmission suggests that future drug design should include evaluation of gametogenesis and sporogonic development.The clinical symptoms of malaria are caused by asexually replicating parasites, but malaria parasite transmission requires that a subpopulation of parasites undergo sexual differentiation. In the species of parasite responsible for the most virulent form of malaria, Plasmodium falciparum, complete maturation into mature stage V gametocytes takes 10 to 12 days in the human host. Once stage V gametocytes are taken up by a mosquito, gametogenesis is stimulated and, after fertilization, the zygote differentiates into an ookinete. The ookinete then migrates to the basal surface of the midgut and forms an oocyst, where tens of thousands of infectious sporozoites are produced.Both asexual and sexual stage parasites are present concurrently in an infected individual and therefore would both be exposed to antimalarial drugs. However, gametocytes have been found to be resistant to many of the commonly used antimalarials, such as the 4-aminoquinolines; and sulfadoxinepyrimethamine has been reported to increase the production of gametocytes, which could enhance transmission (2, 12, 21, 36). Consequently, even after successful treatment for clinical symptoms, an individual can still transmit the malaria parasite for at least a week. Therefore, it is important to d...

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Section: Methodsmentioning

confidence: 99%

Inhibition of Plasmodium falciparum Oocyst Production by Membrane-Permeant Cysteine Protease Inhibitor E64d

Ekşi

Czesny

Gemert³

et al. 2007

Antimicrob Agents Chemother

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“…The P. falciparum NF54 isolate [14] was cultivated in vitro using RPMI 1640 medium supplemented with 10% heat-inactivated human serum and human erythrocytes at a 5% haematocrit as described [15]. Parasite development was synchronized by the isolation of schizonts using a Percoll-Sorbitol gradient and these parasites were placed back in culture.…”

Section: Parasitesmentioning

confidence: 99%

Translational repression of the cpw-wpc gene family in the malaria parasite Plasmodium

Rao

Santos

Pain³

et al. 2016

Parasitology International

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Please cite this article as: Rao Pavitra N., Santos Jorge M., Pain Arnab, Templeton Thomas J., Mair Gunnar R., Translational repression of the cpw-wpc gene family in the malaria parasite Plasmodium, Parasitology International (2016), doi: 10.1016/j.parint.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…26 Human blood used for in vitro culture was freshly drawn from volunteers after informed consent according to a protocol approved by the University of California, San Diego Human Subjects Protection Program. Gametocytes were cultured as previously described 27 (Appendix), and the overall procedure is schematized in Figure 1 . Morphologically mature microgametocytes were seen as early as 12 days for microgametocytes and 14 days macrogametocytes and as late as 22 days for both.…”

Section: High-yield Ookinete Productionmentioning

confidence: 99%

“…To compensate for this lack of synchronization, gametocyte cultures were started 2-3 days apart to ensure that cultures containing mature microgametocytes could be mixed with cultures containing mature macrogametocytes. [26][27][28][29] On days 14-17 of culture, mature microgametocytes were tested for the ability to exflagellate and emerge under standard conditions (Appendix). 30 Two gametocyte cultures with microgametocytes confirmed to be functional (≥ 4 exflagellation centers per 40× field) were combined with two gametocyte cultures with emergence-competent macrogametocytes (≥ 80% macrogamete emergence).…”

Section: High-yield Ookinete Productionmentioning

confidence: 99%