title: Salmonella synthesizing 1-dephosphorylated [corrected] lipopolysaccharide exhibits low endotoxic activity while retaining its immunogenicity.
abstract: The development of safe live, attenuated Salmonella vaccines may be facilitated by detoxification of its LPS. Recent characterization of the lipid A 1-phosphatase, LpxE, from Francisella tularensis allowed us to construct recombinant, plasmid-free strains of Salmonella that produce predominantly 1-dephosphorylated lipid A, similar to the adjuvant approved for human use. Complete lipid A 1-dephosphorylation was also confirmed under low pH, low Mg(2+) culture conditions, which induce lipid A modifications. LpxE expression in Salmonella reduced its virulence in mice by five orders of magnitude. Moreover, mice inoculated with these detoxified strains were protected against wild-type challenge. Candidate Salmonella vaccine strains synthesizing pneumococcal surface protein A (PspA) were also confirmed to possess nearly complete lipid A 1-dephosphorylation. After inoculation by the LpxE/PspA strains, mice produced robust levels of anti-PspA Abs and showed significantly improved survival against challenge with wild-type Streptococcus pneumoniae WU2 compared with vector-only-immunized mice, validating Salmonella synthesizing 1-dephosphorylated lipid A as an Ag-delivery system.
authors.affiliation: Center for Infectious Diseases and Vaccinology, Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Qingke
authors.initials: Q
authors.lastname: Kong
authors.forename: David A
authors.initials: DA
authors.lastname: Six
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Roland
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.forename: Lillian
authors.initials: L
authors.lastname: Gu
authors.forename: C Michael
authors.initials: CM
authors.lastname: Reynolds
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Wang
authors.forename: Christian R H
authors.initials: CR
authors.lastname: Raetz
authors.forename: Roy
authors.initials: R
authors.lastname: Curtiss
mesh_terms: D000276:Adjuvants, Immunologic / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D004731:Endotoxins / Q000276:immunology / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008050:Lipid A / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation / Q000276:immunology; D011817:Rabbits; D022562:Salmonella Vaccines / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019779:Salmonella enterica / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D004731:Endotoxins; D008050:Lipid A; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D022562:Salmonella Vaccines; D014613:Vaccines, Attenuated; C494778:LpxE protein, Francisella tularensis; D010744:Phosphoric Monoester Hydrolases; C048436:monophosphoryl lipid A