Anopheles gambiae eicosanoids modulate Plasmodium berghei survival from oocyst to salivary gland invasion

Eicosanoids affect the immunity of several pathogen/insect models, but their role onthe Anopheles gambiae response to Plasmodium isstill unknown. Plasmodium berghei-infected mosquitoes were injectedwith an eicosanoid biosynthesis inhibitor, indomethacin (IN), or a substrate,arachidonic acid (AA), at day 7 or day 12 post-infection (p.i.). Salivary glandinvasion was evaluated by sporozoite counts at day 21 p.i. IN promoted infection uponsporozoite release from oocysts, but inhibited infection when sporozoites were stillmaturing within the oocysts, as observed by a reduction in the number of sporozoitesreaching the salivary glands. AA treatment had the opposite effect. We show for thefirst time that An. gambiae can modulate parasite survival througheicosanoids by exerting an antagonistic or agonistic effect on the parasite,depending on its stage of development.