title: Molecular and immunological characterization of a novel 32-kDa secreted protein of Babesia microti.
abstract: A cDNA encoding the Babesia microti 32-kDa protein was identified by serological immunoscreening of a cDNA expression library and designated as BmP32. The full length of BmP32 contains an open reading frame of 918 base pairs consisting of 306 amino acids having a significant homology with B. microti secreted antigen 1. Antiserum raised against recombinant protein (rBmP32) specifically reacted with a 32-kDa native protein of the parasite lysate using western blot analysis. The indirect immunofluorescent antibody test showed a preferable localization of BmP32 in the cytoplasm of the intra- and extracellular parasites. Moreover, BmP32 was secreted in the cytosol of infected erythrocytes, especially during the peak parasitemia and the recovery phase of the infection. Next, the antigenicity of rBmP32 was examined by an enzyme-linked immunosorbent assay (ELISA) and sera from mice experimentally infected with either B. microti or closely related parasites. ELISA was highly specific and sensitive when used for the detection of B. microti antibody in a mouse model. Furthermore, mice immunized with rBmP32 emulsified with Freund's adjuvant were not significantly protected against challenge infection with B. microt i. However, high antibody titer was detected just before the challenge infection. Our data suggest that rBmP32 may be a specific diagnostic antigen but not a subunit vaccine.
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ooka
authors.forename: Mohamad A
authors.initials: MA
authors.lastname: Terkawi
authors.forename: Shinuo
authors.initials: S
authors.lastname: Cao
authors.forename: Gabriel
authors.initials: G
authors.lastname: Aboge
authors.forename: Youn-Kyoung
authors.initials: YK
authors.lastname: Goo
authors.forename: Yuzi
authors.initials: Y
authors.lastname: Luo
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nishikawa
authors.forename: Ikuo
authors.initials: I
authors.lastname: Igarashi
authors.forename: Xuenan
authors.initials: X
authors.lastname: Xuan
mesh_terms: D000818:Animals; D041001:Babesia microti / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001404:Babesiosis / Q000175:diagnosis / Q000469:parasitology; D015153:Blotting, Western; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D007106:Immune Sera / Q000276:immunology; D051379:Mice; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D018076:DNA, Complementary; D016054:DNA, Protozoan; D007106:Immune Sera; D015800:Protozoan Proteins; D011994:Recombinant Proteins