title: Virulence attenuation of Babesia gibsoni by serial passages in vitro and assessment of the protection provided by the immunization against the passaged isolate in dogs.
abstract: The virulence of the Babesia gibsoni Oita isolate was attenuated by serial passages in vitro by using the microaerophilus stationary phase (MASP) technique. After 400 serial passages, the virulence of the isolate was found to be attenuated. This was evidenced by the response of two dogs inoculated intravenously with 10(9)B. gibsoni passaged isolate. Specific antibodies were produced at a titer of 1:20,480, as detected by the fluorescent antibody test (IFAT). These results suggested that the serial passages of B. gibsoni reduced its virulence while retaining its antigenicity. The dogs that were inoculated with the attenuated isolate (1 and 2) and two naïve dogs (3 and 4) were challenged by intravenous inoculation of 2×10(8) infected erythrocytes of the virulent Oita isolate. Protection afforded by exposure to the attenuated isolate was evidenced by a lower parasitemia in dogs 1 and 2 with a rapid decrease to nondetectable levels, accompanied by a slight decrease in the PCV that returned to normal values. Dogs 3 and 4 developed typical acute clinical signs, including severe anemia and hyperthermia. These results suggested that the attenuated isolate was a candidate for live vaccine.
authors.affiliation: Laboratory of Infectious Disease, School of Veterinary Medicine, Azabu University, 1-17-71 Fucinobe, Chuo-ku, Sagamihara-shi, Kanagawa 252-5201, Japan. Electronic address: sunaga@azabu-u.ac.jp.
authors.forename: Fujiko
authors.initials: F
authors.lastname: Sunaga
authors.forename: Satoshi
authors.initials: S
authors.lastname: Taharaguchi
authors.forename: Sachiko
authors.initials: S
authors.lastname: Arai
authors.forename: Seigo
authors.initials: S
authors.lastname: Itoh
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Kanno
mesh_terms: D000818:Animals; D001403:Babesia / Q000472:pathogenicity*; D001404:Babesiosis / Q000517:prevention & control / Q000662:veterinary*; D015153:Blotting, Western; D004283:Dog Diseases / Q000469:parasitology / Q000517:prevention & control*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007114:Immunization; D016052:Protozoan Vaccines / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology; D014774:Virulence
chemical_list: D016052:Protozoan Vaccines; D014613:Vaccines, Attenuated
keywords: Babesia gibsoni; Culture; Dogs; Immunity; Virulence attenuation