title: Brucella abortusΔcydCΔcydD and ΔcydCΔpurD double-mutants are highly attenuated and confer long-term protective immunity against virulent Brucella abortus.
abstract: We constructed double deletion (ΔcydCΔcydD and ΔcydCΔpurD) mutants from virulent Brucella abortus biovar 1 field isolate (BA15) by deleting the genes encoding an ATP-binding cassette-type transporter (cydC and cydD genes) and a phosphoribosylamine-glycine ligase (purD). Both BA15ΔcydCΔcydD and BA15ΔcydCΔpurD double-mutants exhibited significant attenuation of virulence when assayed in murine macrophages or in BALB/c mice. Both double-mutants were readily cleared from spleens by 4 weeks post-inoculation even when inoculated at the dose of 10(8) CFU per mouse. Moreover, the inoculated mice showed no splenomegaly, which indicates that the mutants are highly attenuated. Importantly, the attenuation of in vitro and in vivo growth did not impair the ability of these mutants to confer long-term protective immunity in mice against challenge with B. abortus strain 2308. Vaccination of mice with either mutant induced humoral and cell-mediated immune responses, and provided significantly better protection than commercial B. abortus strain RB51 vaccine. These results suggest that highly attenuated BA15ΔcydCΔcydD and BA15ΔcydCΔpurD mutants can be used effectively as potential live vaccine candidates against bovine brucellosis.
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Quang Lam
authors.initials: QL
authors.lastname: Truong
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Youngjae
authors.initials: Y
authors.lastname: Cho
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Soyeon
authors.initials: S
authors.lastname: Park
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Kiju
authors.initials: K
authors.lastname: Kim
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea. Electronic address: twhahn@kangwon.ac.kr.
authors.forename: Tae-Wook
authors.initials: TW
authors.lastname: Hahn
mesh_terms: D000818:Animals; D058491:Bacterial Load; D002004:Brucella Vaccine / Q000235:genetics / Q000276:immunology*; D002003:Brucella abortus / Q000235:genetics* / Q000276:immunology* / Q000472:pathogenicity; D002006:Brucellosis / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D002460:Cell Line; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D008264:Macrophages / Q000382:microbiology; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000382:microbiology / Q000473:pathology; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D002004:Brucella Vaccine; D014613:Vaccines, Attenuated; D037521:Virulence Factors
keywords: Attenuation; Brucella abortus; Immune response; Live attenuated vaccine; Protection