title: A Babesia bovis merozoite protein with a domain architecture highly similar to the thrombospondin-related anonymous protein (TRAP) present in Plasmodium sporozoites.
abstract: Recognition and invasion of host cells is a key step in the life-cycle of all apicomplexan parasites. The thrombospondin-related anonymous protein (TRAP) of Plasmodium sporozoites is directly involved in both processes and shares conserved adhesive domains with micronemal transmembrane proteins of other apicomplexans. Here, we report the cloning and characterization of a Babesia bovis TRAP homologue (BbTRAP). It was predicted to be a type 1 transmembrane protein containing a von Willebrand Factor A domain (vWFA), a thrombospondin type 1 domain (TSP1), a conserved transmembrane region and a conserved cytoplasmic C-terminus, thus resembling the domain arrangement of Plasmodium TRAP. In contrast to Plasmodium TRAP, BbTRAP was shown to be present during the asexual erythrocytic cycle, being located mainly at the apical side of merozoites. Polyclonal rabbit antisera directed against synthetic peptides derived from the TSP1 domain or the C-terminal end of the ectodomain were shown to inhibit erythrocyte invasion in vitro. Both antisera recognized a 75 kDa protein in merozoite extracts as well as in a protein fraction that was secreted into the extracellular milieu during in vitro invasion of erythrocytes.
authors.affiliation: Department of Infectious Diseases and Immunology, Division of Parasitology and Tropical Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
authors.forename: Fasila R
authors.initials: FR
authors.lastname: Gaffar
authors.forename: Ana P
authors.initials: AP
authors.lastname: Yatsuda
authors.forename: Frits F J
authors.initials: FF
authors.lastname: Franssen
authors.forename: Erik
authors.initials: E
authors.lastname: de Vries
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016793:Babesia bovis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity*; D003001:Cloning, Molecular; D004912:Erythrocytes / Q000469:parasitology*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014774:Virulence
chemical_list: D015800:Protozoan Proteins; C069428:thrombospondin-related adhesive protein, protozoan