Imaging movement of malaria parasites during transmission by Anopheles mosquitoes

Authors

  • Friedrich Frischknecht,

    Corresponding author
    1. Unité de Biologie et Génétique du Paludisme, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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  • Patricia Baldacci,

    1. Unité de Biologie et Génétique du Paludisme, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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    • These authors contributed equally to this work.

  • Béatrice Martin,

    1. Unité de Biologie et Génétique du Paludisme, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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    • These authors contributed equally to this work.

  • Christophe Zimmer,

    1. Unité d’Analyse d’Images Quantitative, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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    • These authors contributed equally to this work.

  • Sabine Thiberge,

    1. Unité de Biologie et Génétique du Paludisme, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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  • Jean-Christophe Olivo-Marin,

    1. Unité d’Analyse d’Images Quantitative, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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  • Spencer L. Shorte,

    1. Plate-Forme d’Imagerie Dynamique, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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  • Robert Ménard

    Corresponding author
    1. Unité de Biologie et Génétique du Paludisme, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
    2. Grand Programme Horizontal Anopheles, Institut Pasteur, 25 Rue du Dr Roux, 75015 Paris, France.
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E-mail freddy@pasteur.fr or rmenard@pasteur.fr; Tel. (+33) 1 44389580; Fax (+33) 1 40613089.

Summary

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.

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