title: Secretion of a new spherical body protein of Babesia bovis into the cytoplasm of infected erythrocytes.
abstract: A cDNA encoding a new Babesia bovis spherical body protein 4 (BbSBP-4) was reported to have no significant homology to other apicomplexan proteins or previously reported B. bovis spherical body proteins. In the present study, we further examined the molecular characteristics of BbSBP-4 including the expression and cellular localization of the BbSBP-4. An anti-rBbSBP-4 mouse serum specifically reacted to a 41-kDa native protein B. bovis in Western blot analysis. The immunoelectron microscopic examination confirmed the localization of BbSBP-4 in spherical bodies, but not in the nucleus, rhoptries, and micronemes. Interestingly, the protein was found to be localized not only in the spherical body of B. bovis but also in the cytoplasm of infected erythrocytes (iRBC) at the later stage of parasite development. The confocal laser microscopic examination and Western blot analysis demonstrated the increased accumulation of BbSBP-4 in the cytoplasm of iRBC and in the supernatant of cultivated B. bovis during the late developmental stage of the parasite. These results suggest that BbSBP-4 was secreted from spherical body into cytoplasm of iRBC during the late developmental stage of the parasite before the rupture of infected RBC. Taken together, BbSBP-4 might play an important role as a secreted protein in the intracellular development and/or survival of B. bovis.
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
authors.forename: Mohamad Alaa
authors.initials: MA
authors.lastname: Terkawi
authors.forename: Faasoa Junior
authors.initials: FJ
authors.lastname: Seuseu
authors.forename: Putut
authors.initials: P
authors.lastname: Eko-Wibowo
authors.forename: Nguyen Xuan
authors.initials: NX
authors.lastname: Huyen
authors.forename: Yuka
authors.initials: Y
authors.lastname: Minoda
authors.forename: Mahmoud
authors.initials: M
authors.lastname: AbouLaila
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawai
authors.forename: Naoaki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Xuenan
authors.initials: X
authors.lastname: Xuan
authors.forename: Ikuo
authors.initials: I
authors.lastname: Igarashi
mesh_terms: D000818:Animals; D016793:Babesia bovis / Q000378:metabolism*; D015153:Blotting, Western; D003593:Cytoplasm / Q000737:chemistry / Q000469:parasitology; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004912:Erythrocytes / Q000469:parasitology*; D051379:Mice; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D015388:Organelles / Q000737:chemistry; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins