Editor: Johannes Kusters
Evaluation of phoP and rpoS mutants of Salmonella enterica serovar Typhi as attenuated typhoid vaccine candidates: virulence and protective immune responses in intranasally immunized mice
Article first published online: 24 AUG 2007
FEMS Immunology & Medical Microbiology
Volume 51, Issue 2, pages 310–318, November 2007
How to Cite
Lee, H.-Y., Cho, S.-A., Lee, I.-S., Park, J.-H., Seok, S.-H., Baek, M.-W., Kim, D.-J., Lee, S.-H., Hur, S.-J., Ban, S.-J., Lee, Y.-K., Han, Y.-K., Cho, Y.-K. and Park, J.-H. (2007), Evaluation of phoP and rpoS mutants of Salmonella enterica serovar Typhi as attenuated typhoid vaccine candidates: virulence and protective immune responses in intranasally immunized mice. FEMS Immunology & Medical Microbiology, 51: 310–318. doi: 10.1111/j.1574-695X.2007.00307.x
- Issue published online: 24 AUG 2007
- Article first published online: 24 AUG 2007
- Received 20 December 2006; revised 30 March 2007; accepted 25 June 2007.First published online 24 August 2007.
- Salmonella enterica serovar strain Typhi;
The attenuation and immunoenhancing effects of rpoS and phoPSalmonella enterica serovar strain Typhi (Salmonella typhi) mutants have not been compared. Here, three S. typhi deletion mutants (phoP, rpoS, and rpoS–phoP double mutant) are constructed and these mutants are characterized with respect to invasiveness, virulence, and protective immune response compared with wild-type Ty2. It was found that phoP and phoP–rpoS deletion mutants are less invasive to HT-29 cells than the wild-type Ty2 and the rpoS single-deleted strain. The LD50 of immunized mice was higher for phoP than for rpoS mutants, and the highest for the phoP–rpoS double mutant. In addition, all S. typhi mutants showed an increase in the specific serum IgG levels and T-cell-mediated immunity, and showed equal protection abilities against a wild-type Ty2 challenge after two rounds of immunization in BALB/c mice. It is concluded that phoP genes appear to play a more important role than rpoS genes in both cellular invasion and virulence of S. typhi, but not in immunogenicity in mice. Furthermore, the data indicate that the phoP–rpoS double mutant may show promise as a candidate for an attenuated typhoid vaccine.