title: A cysteine protease inhibitor of plasmodium berghei is essential for exo-erythrocytic development.
abstract: Plasmodium parasites express a potent inhibitor of cysteine proteases (ICP) throughout their life cycle. To analyze the role of ICP in different life cycle stages, we generated a stage-specific knockout of the Plasmodium berghei ICP (PbICP). Excision of the pbicb gene occurred in infective sporozoites and resulted in impaired sporozoite invasion of hepatocytes, despite residual PbICP protein being detectable in sporozoites. The vast majority of these parasites invading a cultured hepatocyte cell line did not develop to mature liver stages, but the few that successfully developed hepatic merozoites were able to initiate a blood stage infection in mice. These blood stage parasites, now completely lacking PbICP, exhibited an attenuated phenotype but were able to infect mosquitoes and develop to the oocyst stage. However, PbICP-negative sporozoites liberated from oocysts exhibited defective motility and invaded mosquito salivary glands in low numbers. They were also unable to invade hepatocytes, confirming that control of cysteine protease activity is of critical importance for sporozoites. Importantly, transfection of PbICP-knockout parasites with a pbicp-gfp construct fully reversed these defects. Taken together, in P. berghei this inhibitor of the ICP family is essential for sporozoite motility but also appears to play a role during parasite development in hepatocytes and erythrocytes.
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Lehmann
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Heitmann
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Satish
authors.initials: S
authors.lastname: Mishra
authors.affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland.
authors.forename: Paul-Christian
authors.initials: PC
authors.lastname: Burda
authors.affiliation: University of Heidelberg Medical School, Heidelberg, Germany.
authors.forename: Mirko
authors.initials: M
authors.lastname: Singer
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Monica
authors.initials: M
authors.lastname: Prado
authors.affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland.
authors.forename: Livia
authors.initials: L
authors.lastname: Niklaus
authors.affiliation: Institute Pasteur, Unité de Biologie et Génétique du Paludisme, Paris, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Lacroix
authors.affiliation: Institute Pasteur, Unité de Biologie et Génétique du Paludisme, Paris, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Ménard
authors.affiliation: University of Heidelberg Medical School, Heidelberg, Germany.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Frischknecht
authors.affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Stanway
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Photini
authors.initials: P
authors.lastname: Sinnis
authors.affiliation: Institute of Cell Biology, University of Bern, Bern, Switzerland.
authors.forename: Volker
authors.initials: V
authors.lastname: Heussler
mesh_terms: D000818:Animals; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism*; D004912:Erythrocytes / Q000469:parasitology; D005455:Fluorescent Antibody Technique; D055786:Gene Knockout Techniques; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000469:parasitology; D006801:Humans; D008018:Life Cycle Stages; D008288:Malaria / Q000378:metabolism / Q000469:parasitology*; D051379:Mice; D010962:Plasmodium berghei / Q000254:growth & development* / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D015853:Cysteine Proteinase Inhibitors; D015800:Protozoan Proteins