title: A Babesia bovis 225-kilodalton spherical-body protein: localization to the cytoplasmic face of infected erythrocytes after merozoite invasion.
abstract: A 225-kDa Babesia bovis protein occurs on the cytoplasmic side of infected-erythrocyte membranes. Here it is demonstrated that the 225-kDa protein localizes to spherical-body organelles of merozoites. Organelles consistent in size and shape with spherical bodies were isolated between 1.17 and 1.21 g/cm(3) in a sucrose density gradient. Organelles consistent with rhoptries and micronemes were also present in fractions from 1.17 to 1.19 g/cm(3). Antisera generated by immunizing mice with the fraction (1.20 to 1.21 g/cm(3)) most enriched for spherical bodies reacted predominantly with spherical bodies in B. bovis merozoites. A monoclonal antibody generated from this immunization (70/97.14) recognized an epitope that occurs in the repeat region of the 225-kDa protein (now referred to as SBP2). Monoclonal antibody 70/97.14 bound to merozoite spherical bodies, vesicles in infected-host cytoplasm, and the cytoplasmic face of the infected-erythrocyte membrane. These results indicate that spherical-body proteins become associated with the host membrane via transport through the erythrocyte cytoplasm after intracellular invasion.
authors.affiliation: Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-7040, USA. dud@vetmed.wsu.edu
authors.forename: S C
authors.initials: SC
authors.lastname: Dowling
authors.forename: L E
authors.initials: LE
authors.lastname: Perryman
authors.forename: D P
authors.initials: DP
authors.lastname: Jasmer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016793:Babesia bovis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D001404:Babesiosis / Q000469:parasitology; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology; D003593:Cytoplasm / Q000378:metabolism / Q000469:parasitology; D000939:Epitopes / Q000235:genetics / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology* / Q000648:ultrastructure; D066298:In Vitro Techniques; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015388:Organelles / Q000378:metabolism / Q000648:ultrastructure; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000939:Epitopes; D015800:Protozoan Proteins