title: Characterization of a highly attenuated Salmonella enterica serovar Typhimurium mutant strain.
abstract: Salmonella enterica serovar Typhimurium ATCC 13311 is virulent at a dose as low as 10(2) colony-forming units when administered intraperitoneally to BALB/c mice. In order to develop highly attenuated mutant strain through the combination of 2 phenotypically attenuated markers, we constructed a number of amino acid requiring auxotrophic strains of S. enterica serovar Typhimurium by means of UV-induced mutations. One of them, strain NDMC-B1, was highly attenuated for mice, with an LD50-value of 6 and 3 log units lower for mice than the wild-type strain and S. enterica serovar Typhimurium aroA strain, respectively. This strain still contained the Salmonella O- and H-antigens but had a requirement for cysteine and was unable to utilize citrate as its sole carbon source. NDMC-B1 colonized the gut-associated lymphoid tissue more efficiently than the wild-type strain, but its capacities to colonize spleen and liver were significantly reduced. Mice intraperitoneally or orally vaccinated with NDMC-B1 were highly protected against either an intraperitoneal challenge with 10(6) colony-forming units or an oral challenge with 10(9) colony-forming units of the wild-type strain. Taken together, the results illustrate that through the combination of 2 independently phenotypical attenuating markers, the requirement for cysteine and the inability to use citrate, we have successfully constructed a highly attenuated, stable, and immunogenic S. enterica serovar Typhimurium vaccine strain which can induce protective immunity in a mouse model against lethal challenge of wild-type strain.
authors.affiliation: Institute of Microbiology and Immunology, National Defense Medical Center Taipei, Taiwan, ROC.
authors.forename: Ing-Kae
authors.initials: IK
authors.lastname: Tang
authors.forename: Dar-Der
authors.initials: DD
authors.lastname: Ji
authors.forename: Chi-Fu
authors.initials: CF
authors.lastname: Chou
authors.forename: Hung-Chi
authors.initials: HC
authors.lastname: Lin
authors.forename: Chin-Len
authors.initials: CL
authors.lastname: Liao
authors.forename: Huey-Kang
authors.initials: HK
authors.lastname: Sytwu
authors.forename: Jaang-Jiun
authors.initials: JJ
authors.lastname: Wang
authors.forename: Yu-Tien
authors.initials: YT
authors.lastname: Liu
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D019343:Citric Acid / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D007274:Injections, Intraperitoneal / Q000379:methods; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012480:Salmonella Infections / Q000517:prevention & control*; D022562:Salmonella Vaccines / Q000235:genetics / Q000276:immunology; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D014466:Ultraviolet Rays; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D022562:Salmonella Vaccines; D014613:Vaccines, Attenuated; D019343:Citric Acid; D003545:Cysteine