title: Imaging movement of malaria parasites during transmission by Anopheles mosquitoes.
abstract: Malaria is contracted when Plasmodium sporozoites are inoculated into the vertebrate host during the blood meal of a mosquito. In infected mosquitoes, sporozoites are present in large numbers in the secretory cavities of the salivary glands at the most distal site of the salivary system. However, how sporozoites move through the salivary system of the mosquito, both in resting and feeding mosquitoes, is unknown. Here, we observed fluorescent Plasmodium berghei sporozoites within live Anopheles stephensi mosquitoes and their salivary glands and ducts. We show that sporozoites move in the mosquito by gliding, a type of motility associated with their capacity to invade host cells. Unlike in vitro, sporozoite gliding inside salivary cavities and ducts is modulated in speed and motion pattern. Imaging of sporozoite discharge through the proboscis of salivating mosquitoes indicates that sporozoites need to locomote from cavities into ducts to be ejected and that their progression inside ducts favours their early ejection. These observations suggest that sporozoite gliding allows not only for cell invasion but also for parasite locomotion in host tissues, and that it may control parasite transmission.
authors.affiliation: Unité de Biologie et Génétique du Paludisme and Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France. freddy@pasteur.fr
authors.forename: Friedrich
authors.initials: F
authors.lastname: Frischknecht
authors.forename: Patricia
authors.initials: P
authors.lastname: Baldacci
authors.forename: Béatrice
authors.initials: B
authors.lastname: Martin
authors.forename: Christophe
authors.initials: C
authors.lastname: Zimmer
authors.forename: Sabine
authors.initials: S
authors.lastname: Thiberge
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Olivo-Marin
authors.forename: Spencer L
authors.initials: SL
authors.lastname: Shorte
authors.forename: Robert
authors.initials: R
authors.lastname: Ménard
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology* / Q000502:physiology; D005247:Feeding Behavior; D049452:Green Fluorescent Proteins; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007303:Insect Vectors / Q000469:parasitology / Q000502:physiology; D008164:Luminescent Proteins / Q000378:metabolism; D008288:Malaria / Q000469:parasitology / Q000635:transmission*; D051379:Mice; D008853:Microscopy / Q000295:instrumentation / Q000379:methods; D009068:Movement; D010962:Plasmodium berghei / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D051381:Rats; D012469:Salivary Glands / Q000469:parasitology*
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins