C-type lectin 4 regulates broad-spectrum melanization-based refractoriness to malaria parasites

Anopheles gambiae melanization-based refractoriness to the human malaria parasite Plasmodium falciparum has rarely been observed in either laboratory or natural conditions, in contrast to the rodent model malaria parasite Plasmodium berghei that can become completely melanized by a TEP1 complement-like system-dependent mechanism. Multiple studies have shown that the rodent parasite evades this defense by recruiting the C-type lectins CTL4 and CTLMA2, while permissiveness to the human malaria parasite was not affected by partial depletion of these factors by RNAi silencing. Using CRISPR/Cas9-based CTL4 knockout, we show that A. gambiae can mount melanization-based refractoriness to the human malaria parasite, which is independent of the TEP1 complement-like system and the major anti-Plasmodium immune pathway Imd. Our study indicates a hierarchical specificity in the control of Plasmodium melanization and proves CTL4 as an essential host factor for P. falciparum transmission and one of the most potent mosquito-encoded malaria transmission-blocking targets.

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Genetic alteration of ferredoxin NADP+-reductase or cysteine desulfurase in piperaquine-resistant Plasmodium berghei restores susceptibility to lumefantrine and abolishes the impact of probenecid, verapamil, and cyproheptadine

10.1101/833145 ◽

2019 ◽

Author(s):

Fagdéba David Bara ◽

Loise Ndung’u ◽

Noah Machuki Onchieku ◽

Beatrice Irungu ◽

Simplice Damintoti Karou ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Plasmodium Berghei ◽

Malaria Parasite ◽

Drug Action ◽

Cysteine Desulfurase ◽

Human Malaria Parasite ◽

Human Malaria ◽

Essential Components ◽

The Impact

AbstractChemotherapy remains central in the control of malaria; however, resistance has consistently thwarted these efforts. Currently, lumefantrine (LM), and piperaquine (PQ) drugs, are essential components in the mainstay artemisinin-based therapies used for the treatment of malaria globally. Using LM and PQ-resistant Plasmodium berghei, we measured the effect of known chemosensitizers: probenecid, verapamil, or cyproheptadine on the activity of LM or PQ. Using PlasmoGEM vectors, we then evaluated the impact of deleting cysteine desulfurase (SufS) or over-expressing Ferredoxin NADP+ reductase (FNR), genes that mediate drug action. Our data showed that, only cyproheptadine at 5mgkg−1 restored LM activity by above 65% against the LM-resistant parasites (LMR) but failed to reinstate PQ activity against the PQ-resistant parasites (PQR). Whereas the PQR had lost significant susceptibility to LM, the three chemosensitizers; cyproheptadine, probenecid, and verapamil, restored LM potency against the PQR by above 70%, 60%, and 55% respectively. We thus focused on LM resistance in PQR. Deletion of the SufS or overexpression of the FNR genes in the PQR abolished the impact of the chemosensitizers on the LM activity, and restored the susceptibility of the PQR parasites to LM. Taken together, we demonstrate the association between SufS or FNR genes with the action of LM and chemosensitizers in PQR parasites. There is, however, need to interrogate the impact of the chemosensitizers and the role of SufS or FNR genes on LM action in the human malaria parasite, Plasmodium falciparum.

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