Table 1 Bacterial strains and plasmids used in this study

Strains

 Χ232

E. coli Δasd strain, used for cloning of genes into asd⁺ plasmid

[28]

 JOL394

Salmonella Gallinarum wild-type challenge strain

[28]

 JOL967

∆lon, ∆cpxR and ∆asd mutant of S. Gallinarum

[28]

 JOL916

∆lon, ∆cpxR mutant of S. Gallinarum

[28]

 JOL2068

JOL967 with pJHL65 empty plasmid

[44]

 JOL2074

JOL967 with pJHL65-M2eCD40L plasmid

This study

 JOL2076

JOL967 with pJHL65 plus pcDNA-M2eCD40L

This study

Plasmids

 pJHL65

An asd⁺ vector, pBR ori, β-lactamase signal sequence-based periplasmic secretion plasmid, 6xHis, high copy number

[21]

 pcDNA3.1+

Mammalian expression vector, CMV promoter, high copy number

(Invitrogen, USA)

 pET-32a

IPTG-inducible expression vector; Kanamycin resistant

(Novagen, USA)

 pET32a-M2eCD40L

M2e-CD40L gene in pET32a vector

This study