title: Engineering of a live Salmonella enterica serovar Choleraesuis negative-marker strain that allows serological differentiation between immunised and infected animals.
abstract: The usefulness of Salmonella vaccine vehicles is limited by the fact that control programmes relying on Salmonella bacteriology and serology cannot differentiate infected animals from vaccinated ones, an ability referred to as DIVA (differentiating infected from vaccinated animals). As a first step towards Salmonella-based DIVA vaccines, the ompA gene was deleted in live attenuated ΔphoP and ΔrpoS vaccine strains. The ompA gene is present in all Salmonella enterica serovars and it encodes an abundant, highly immunogenic outer membrane protein. The double mutant ΔphoP ΔompA and ΔrpoS ΔompA strains showed similar virulence attenuation, safety and immunogenicity in a mouse model of infection as the parental ΔphoP and ΔrpoS strains. Sera from mice inoculated with the double mutant strains failed to recognise OmpA in Western blots of outer membrane extracts, whereas the protein was recognised by sera from mice inoculated with wild-type Salmonella or a mixture of double mutant and parental strains. These data suggest that OmpA can be a suitable negative marker for DIVA vaccines.
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Aldara
authors.initials: A
authors.lastname: Herrero-Gil
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Carrión
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Orden
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: de la Fuente
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain. Electronic address: gdbernal@ucm.es.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Domínguez-Bernal
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D051379:Mice; D008807:Mice, Inbred BALB C; D015202:Protein Engineering / Q000662:veterinary; D022562:Salmonella Vaccines / Q000276:immunology*; D019779:Salmonella enterica / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity*; D065288:Serogroup; D014613:Vaccines, Attenuated / Q000276:immunology; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D022562:Salmonella Vaccines; D014613:Vaccines, Attenuated; C078167:OMPA outer membrane proteins
keywords: Attenuated DIVA strain; OmpA; Salmonella Choleraesuis; Vaccine delivery vector