A live attenuated strain of Yersinia pestis KIM as a vaccine against plague

Vaccine. 2011 Apr 5;29(16):2986-98. doi: 10.1016/j.vaccine.2011.01.099. Epub 2011 Feb 12.

Abstract

Yersinia pestis, the causative agent of plague, is a potential weapon of bioterrorism. Y. pestis evades the innate immune system by synthesizing tetra-acylated lipid A with poor Toll-like receptor 4 (TLR4)-stimulating activity at 37°C, whereas hexa-acylated lipid A, a potent TLR4 agonist, is made at lower temperatures. Synthesis of Escherichia coli LpxL, which transfers the secondary laurate chain to the 2'-position of lipid A, in Y. pestis results in production of hexa-acylated lipid A at 37°C, leading to significant attenuation of virulence. Previously, we described a Y. pestis vaccine strain in which crp expression is under the control of the arabinose-regulated araC P(BAD) promoter, resulting in a 4-5 log reduction in virulence. To reduce the virulence of the crp promoter mutant further, we introduced E. coli lpxL into the Y. pestis chromosome. The χ10030(pCD1Ap) (ΔlpxP32::P(lpxL)lpxL ΔP(crp21)::TT araC P(BAD)crp) construct likewise produced hexa-acylated lipid A at 37°C and was significantly more attenuated than strains harboring each individual mutation. The LD(50) of the mutant in mice, when administered subcutaneously or intranasally was >10(7)-times and >10(4)-times greater than wild type, respectively. Mice immunized subcutaneously with a single dose of the mutant were completely protected against a subcutaneous challenge of 3.6×10(7) wild-type Y. pestis and significantly protected (80% survival) against a pulmonary challenge of 1.2×10(4) live cells. Intranasal immunization also provided significant protection against challenges by both routes. This mutant is an immunogenic, highly attenuated live Y. pestis construct that merits further development as a vaccine candidate.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Acyltransferases / genetics
  • Acyltransferases / immunology
  • Administration, Intranasal
  • Animals
  • Antibodies, Bacterial / blood
  • Cytokines / immunology
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / immunology
  • Female
  • Injections, Subcutaneous
  • Lipid A / immunology*
  • Mice
  • Plague / immunology
  • Plague / pathology
  • Plague / prevention & control*
  • Plague Vaccine / genetics
  • Plague Vaccine / immunology*
  • Plasmids
  • Promoter Regions, Genetic
  • Vaccines, Attenuated / genetics
  • Vaccines, Attenuated / immunology
  • Virulence
  • Yersinia pestis / genetics*
  • Yersinia pestis / immunology
  • Yersinia pestis / pathogenicity

Substances

  • Antibodies, Bacterial
  • Cytokines
  • Escherichia coli Proteins
  • Lipid A
  • Plague Vaccine
  • Vaccines, Attenuated
  • Acyltransferases
  • LpxL protein, E coli