title: Roles of the amino terminal region and repeat region of the Plasmodium berghei circumsporozoite protein in parasite infectivity.
abstract: The circumsporozoite protein (CSP) plays a key role in malaria sporozoite infection of both mosquito salivary glands and the vertebrate host. The conserved Regions I and II have been well studied but little is known about the immunogenic central repeat region and the N-terminal region of the protein. Rodent malaria Plasmodium berghei parasites, in which the endogenous CS gene has been replaced with the avian Plasmodium gallinaceum CS (PgCS) sequence, develop normally in the A. stephensi mosquito midgut but the sporozoites are not infectious. We therefore generated P. berghei transgenic parasites carrying the PgCS gene, in which the repeat region was replaced with the homologous region of P. berghei CS (PbCS). A further line, in which both the N-terminal region and repeat region were replaced with the homologous regions of PbCS, was also generated. Introduction of the PbCS repeat region alone, into the PgCS gene, did not rescue sporozoite species-specific infectivity. However, the introduction of both the PbCS repeat region and the N-terminal region into the PgCS gene completely rescued infectivity, in both the mosquito vector and the mammalian host. Immunofluorescence experiments and western blot analysis revealed correct localization and proteolytic processing of CSP in the chimeric parasites. The results demonstrate, in vivo, that the repeat region of P. berghei CSP, alone, is unable to mediate sporozoite infectivity in either the mosquito or the mammalian host, but suggest an important role for the N-terminal region in sporozoite host cell invasion.
authors.affiliation: Department of Experimental Medicine, University of Perugia, Perugia Italy.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Aldrich
authors.forename: Alessandro
authors.initials: A
authors.lastname: Magini
authors.forename: Carla
authors.initials: C
authors.lastname: Emiliani
authors.forename: Tania
authors.initials: T
authors.lastname: Dottorini
authors.forename: Francesco
authors.initials: F
authors.lastname: Bistoni
authors.forename: Andrea
authors.initials: A
authors.lastname: Crisanti
authors.forename: Roberta
authors.initials: R
authors.lastname: Spaccapelo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D009033:Culicidae; D000939:Epitopes / Q000737:chemistry; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence / Q000379:methods; D008969:Molecular Sequence Data; D010962:Plasmodium berghei / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D034101:Sporozoites; D019076:Transgenes
chemical_list: D000939:Epitopes; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan