title: Genetic detoxification of an aroA Salmonella enterica serovar Typhimurium vaccine strain does not compromise protection against virulent Salmonella and enhances the immune responses towards a protective malarial antigen.
abstract: Live Salmonella vaccines are limited in use by the inherent toxicity of the lipopolysaccharide. The waaN gene encodes a myristyl transferase required for the secondary acylation of lipid A in lipopolysaccharide. A waaN mutant exhibits reduced induction of the inflammatory cytokines associated with lipopolysaccharide toxicity. Here the characteristics of a Salmonella enterica serovar Typhimurium aroA waaN mutant (SK100) in vitro and in vivo compared with its parent aroA strain (SL3261) were described. Phenotypic analysis of purified lipopolysaccharide obtained from SK100 confirmed that the physical and biological activities of the lipopolysaccharide had been altered. Nevertheless both strains had similar patterns of colonization and persistence in mice and significantly the aroA waaN mutant was equally as effective as the parent at protecting against challenge with wild-type S. Typhimurium. Furthermore, a SK100 strain was constructed expressing both tetanus toxin fragment C and the circumsporozoite protein of a malaria parasite. In marked contrast to its isogenic parent, the new attenuated strain induces significantly enhanced immune responses against the circumsporozoite protein. The waaN mutation enhances the ability of this strain to elicit immune responses towards guest antigens. This study provides important insights into the development of safe and effective multivalent Salmonella vaccines.
authors.affiliation: Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Newcastle Upon Tyne, UK.
authors.forename: Nicola D
authors.initials: ND
authors.lastname: McKelvie
authors.forename: Shahid A
authors.initials: SA
authors.lastname: Khan
authors.forename: Michail H
authors.initials: MH
authors.lastname: Karavolos
authors.forename: David M
authors.initials: DM
authors.lastname: Bulmer
authors.forename: Jeong Jin
authors.initials: JJ
authors.lastname: Lee
authors.forename: Raquel
authors.initials: R
authors.lastname: DeMarco
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Maskell
authors.forename: Fidel
authors.initials: F
authors.lastname: Zavala
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Hormaeche
authors.forename: C M Anjam
authors.initials: CM
authors.lastname: Khan
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000913:Antibodies, Protozoan / Q000097:blood; D001426:Bacterial Proteins / Q000235:genetics; D002460:Cell Line; D015169:Colony Count, Microbial; D005260:Female; D008070:Lipopolysaccharides / Q000302:isolation & purification / Q000633:toxicity; D008099:Liver / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology; D017780:Malaria Vaccines / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification / Q000633:toxicity; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology; D012480:Salmonella Infections / Q000276:immunology / Q000517:prevention & control; D022562:Salmonella Vaccines / Q000235:genetics / Q000276:immunology*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity; D013154:Spleen / Q000382:microbiology; D013744:Tetanus Toxin / Q000235:genetics / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014436:Typhoid-Paratyphoid Vaccines / Q000235:genetics; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000913:Antibodies, Protozoan; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D017780:Malaria Vaccines; D010446:Peptide Fragments; D011135:Polysaccharides, Bacterial; D015800:Protozoan Proteins; D022562:Salmonella Vaccines; D013744:Tetanus Toxin; D014409:Tumor Necrosis Factor-alpha; D014436:Typhoid-Paratyphoid Vaccines; D014613:Vaccines, Attenuated; C087350:aroA Salmonella vaccine; C432063:circumsporozoite protein (282-383), Plasmodium falciparum; C040635:tetanus toxin fragment C