Malaria is a mosquito-borne disease affecting millions of people mainly in Sub-Saharan Africa, Asia and some South American countries. Drug resistance to first-line antimalarial drugs (e.g. chloroquine, sulfadoxine-pyrimethamine and artemisinin) is a major constrain in malaria control. Antimicrobial peptides (AMPs) have shown promising results in controlling Plasmodium spp. parasitemia in in vitro and in vivo models of infection. Defensins are AMPs that act primarily by disrupting the integrity of cell membranes of invasive microbes. We previously showed that defensins from the tick Ixodes ricinus inhibited significantly the growth of P. falciparum in vitro, a property that was conserved during evolution. Here, we tested the activity of three I. ricinus defensins against P. chabaudi in mice. A single dose of defensin (120 μl of 1 mg/ml solution) was administered intravenously to P. chabaudi-infected mice, and the parasitemia was followed for 24 h post-treatment. Defensin treatment inhibited significantly the replication (measured as increases in parasitemia) of P. chabaudi after 1 h and 12 h of treatment. Furthermore, defensin injection was not associated with toxicity. These results agreed with the previous report of antiplasmodial activity of tick defensins against P. falciparum in vitro and justify further studies for the use of tick defensins to control malaria.

Fraunhofer Institute for Molecular Biology and Applied Ecology Winchester Strasse 2 D 35394 Giessen Germany

Fraunhofer Institute for Molecular Biology and Applied Ecology Winchester Strasse 2 D 35394 Giessen Germany; Institute for Insect Biotechnology Justus Liebig University of Giessen Heinrich Buff Ring 26 32 35392 Giessen Germany

Global Health and Tropical Medicine Instituto de Higiene e Medicina Universidade Nova de Lisboa Rua da Junqueira 100 1349 008 Lisboa Portugal

SaBio Instituto de Investigación en Recursos Cinegéticos IREC 13005 Ciudad Real Spain; Department of Veterinary Pathobiology Center for Veterinary Health Sciences Oklahoma State University Stillwater OK 74078 USA

UMR BIPAR INRA ANSES Ecole Nationale Vétérinaire d'Alfort Université Paris Est Maisons Alfort 94700 France; Faculty of Science University of South Bohemia 37005 České Budějovice Czech Republic; Institute of Parasitology Biology Center Czech Academy of Sciences 37005 České Budějovice Czech Republic

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Tick defensin γ-core reduces Fusarium graminearum growth and abrogates mycotoxins production with high efficiency