title: Salmonella enterica serovar typhimurium strains with regulated delayed attenuation in vivo.
abstract: Recombinant bacterial vaccines must be fully attenuated for animal or human hosts to avoid inducing disease symptoms while exhibiting a high degree of immunogenicity. Unfortunately, many well-studied means for attenuating Salmonella render strains more susceptible to host defense stresses encountered following oral vaccination than wild-type virulent strains and/or impair their ability to effectively colonize the gut-associated and internal lymphoid tissues. This thus impairs the ability of recombinant vaccines to serve as factories to produce recombinant antigens to induce the desired protective immunity. To address these problems, we designed strains that display features of wild-type virulent strains of Salmonella at the time of immunization to enable strains first to effectively colonize lymphoid tissues and then to exhibit a regulated delayed attenuation in vivo to preclude inducing disease symptoms. We recently described one means to achieve this based on a reversible smooth-rough synthesis of lipopolysaccharide O antigen. We report here a second means to achieve regulated delayed attenuation in vivo that is based on the substitution of a tightly regulated araC P(BAD) cassette for the promoters of the fur, crp, phoPQ, and rpoS genes such that expression of these genes is dependent on arabinose provided during growth. Thus, following colonization of lymphoid tissues, the Fur, Crp, PhoPQ, and/or RpoS proteins cease to be synthesized due to the absence of arabinose such that attenuation is gradually manifest in vivo to preclude induction of diseases symptoms. Means for achieving regulated delayed attenuation can be combined with other mutations, which together may yield safe efficacious recombinant attenuated Salmonella vaccines.
authors.affiliation: Center for Infectious Diseases and Vaccinology, Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona 85287-5401, USA. rcurtiss@asu.edu
authors.forename: Roy
authors.initials: R
authors.lastname: Curtiss
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Wanda
authors.forename: Bronwyn M
authors.initials: BM
authors.lastname: Gunn
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Steven A
authors.initials: SA
authors.lastname: Tinge
authors.forename: Vidya
authors.initials: V
authors.lastname: Ananthnarayan
authors.forename: Hua
authors.initials: H
authors.lastname: Mo
authors.forename: Shifeng
authors.initials: S
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Kong
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005797:Genes, araC / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009154:Mutation; D010641:Phenotype; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics; D022562:Salmonella Vaccines / Q000276:immunology*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D012808:Sigma Factor / Q000096:biosynthesis / Q000235:genetics; D014613:Vaccines, Attenuated; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C063931:Omp2 protein, bacteria; C079792:PhoQ protein, Bacteria; D012097:Repressor Proteins; D022562:Salmonella Vaccines; D012808:Sigma Factor; D014613:Vaccines, Attenuated; C068477:ferric uptake regulating proteins, bacterial; C069567:sigma factor KatF protein, Bacteria