Differential transcriptome profiling identifies Plasmodium genes encoding pre-erythrocytic stage-specific proteins

Authors

  • Karine Kaiser,

    1. Michael Heidelberger Division, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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    • These authors contributed equally to this work.

  • Kai Matuschewski,

    1. Department of Parasitology, Heidelberg University School of Medicine, Heidelberg, Germany.
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    • These authors contributed equally to this work.

  • Nelly Camargo,

    1. Michael Heidelberger Division, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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    • Present address: Seattle Biomedical Research Institute, 4 Nickerson Street, Suite 200, Seattle, WA 98109, USA.

  • Jessica Ross,

    1. Michael Heidelberger Division, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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  • Stefan H. I. Kappe

    Corresponding author
    1. Michael Heidelberger Division, Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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    • Present address: Seattle Biomedical Research Institute, 4 Nickerson Street, Suite 200, Seattle, WA 98109, USA.


E-mail stefan.kappe@sbri.org; Tel. (+1) 206 284 8846, Ext. 505; Fax (+1) 206 284 0313.

Summary

Invasive sporozoite and merozoite stages of malaria parasites that infect mammals enter and subsequently reside in hepatocytes and red blood cells respectively. Each invasive stage may exhibit unique adaptations that allow it to interact with and survive in its distinct host cell environment, and these adaptations are likely to be controlled by differential gene expression. We used suppression subtractive hybridization (SSH) of Plasmodium yoelii salivary gland sporozoites versus merozoites to identify stage-specific pre-erythrocytic transcripts. Sequencing of the SSH library and matching the cDNA sequences to the P. yoelii genome yielded 25 redundantly tagged genes including the only two previously characterized sporozoite-specific genes encoding the circumsporozoite protein (CSP) and thrombospondin-related anonymous protein (TRAP). Twelve novel genes encode predicted proteins with signal peptides, indicating that they enter the secretory pathway of the sporozoite. We show that one novel protein bearing a thrombospondin type 1 repeat (TSR) exhibits an expression pattern that suggests localization in the sporozoite secretory rhoptry organelles. In addition, we identified a group of four genes encoding putative low-molecular-mass proteins. Two proteins in this group exhibit an expression pattern similar to TRAP, and thus possibly localize in the sporozoite secretory micronemes. Proteins encoded by the differentially expressed genes identified here probably mediate specific interactions of the sporozoite with the mosquito vector salivary glands or the mammalian host hepatocyte and are not used during merozoite–red blood cell interactions.

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