title: A live attenuated strain of Yersinia pestis KIM as a vaccine against plague.
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.
authors.affiliation: Center for Infectious Disease and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: David
authors.initials: D
authors.lastname: Six
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Kuang
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Roland
authors.forename: Christian R H
authors.initials: CR
authors.lastname: Raetz
authors.forename: Roy
authors.initials: R
authors.lastname: Curtiss
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000276:immunology; D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D016207:Cytokines / Q000276:immunology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000276:immunology; D005260:Female; D007279:Injections, Subcutaneous; D008050:Lipid A / Q000276:immunology*; D051379:Mice; D010930:Plague / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D010931:Plague Vaccine / Q000235:genetics / Q000276:immunology*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology; D014774:Virulence; D015010:Yersinia pestis / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity
chemical_list: D000907:Antibodies, Bacterial; D016207:Cytokines; D029968:Escherichia coli Proteins; D008050:Lipid A; D010931:Plague Vaccine; D014613:Vaccines, Attenuated; D000217:Acyltransferases; C492237:LpxL protein, E coli