A malarial cysteine protease is necessary for Plasmodium sporozoite egress from oocysts

Creative Commons License

Aly A. S. I., Matuschewski K.

JOURNAL OF EXPERIMENTAL MEDICINE, vol.202, no.2, pp.225-230, 2005 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 202 Issue: 2
  • Publication Date: 2005
  • Doi Number: 10.1084/jem.20050545
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.225-230
  • Bezmialem Vakıf University Affiliated: Yes


The Plasmodium life cycle is a sequence of alternating invasive and replicative stages within the vertebrate and invertebrate hosts. How malarial parasites exit their host cells after completion of reproduction remains largely unsolved. Inhibitor studies indicated a role of Plasmodium cysteine proteases in merozoite release from host erythrocytes. To validate a vital function of malarial cysteine proteases in active parasite egress, we searched for target genes that can be analyzed functionally by reverse genetics. Herein, we describe a complete arrest of Plasmodium sporozoite egress from Anopheles midgut oocysts by targeted disruption of a stage-specific cysteine protease. Our findings show that sporozoites exit oocysts by parasite-dependent proteolysis rather than by passive oocyst rupture resulting from parasite growth. We provide genetic proof that malarial cysteine proteases are necessary for egress of invasive stages from their intracellular compartment and propose that similar cysteine protease-dependent mechanisms occur during egress from liver-stage and blood-stage schizonts.