A recombinant Salmonella enterica serovar Typhimurium (S. Typhimurium) vaccine strain was constructed that stably expressed the Mycobacterium tuberculosis fusion antigen Ag85B-ESAT6 from the chromosome. Live oral vaccination of mice with the Salmonella/Ag85B-ESAT6 strain generated a potent anti-Ag85B-ESAT6 TH1 response with high antibody titres with a IgG2a-bias and significant IFN-γ production lasting over a 120-day period. When mice primed with the Salmonella/Ag85B-ESAT6 vaccine were mucosally boosted with the Ag85B-ESAT6 antigen and adjuvant the IFN-γ responses increased markedly. To determine the protective efficacy of this vaccine strain, guinea pigs were immunised and followed for a 30-week period after aerosol challenge with M. tuberculosis. The heterologous prime-boost strategy of live Salmonella vaccine followed by a systemic boost of antigen and adjuvant reduced the levels of M. tuberculosis bacteria in the lungs and spleen to the same extent as BCG. Additionally, this vaccination regimen was observed to be statistically equivalent in terms of protection to immunisation with BCG. Thus, live oral priming with the recombinant Salmonella/Ag85B-ESAT6 and boosting with Ag85B-ESAT6 plus the adjuvant LTK63 represents an effective mucosal vaccination regimen.
|Number of pages||11|
|Publication status||Published - 16 Nov 2009|
Bibliographical noteFunding Information:
This study was carried out with financial support from the Commission of the European Communities, Sixth Framework Programme, contract LSHP-CT-2003-503240, Mucosal Vaccines for Poverty-Related Diseases (MUVAPRED) and The Wellcome Trust. We would also like to thank Novartis, Italy, for their kind gifts of purified LT and LTK63, and Statens Serum Institute, Denmark for Ag85B–ESAT6. The staff in the biological investigations group are sincerely thanked for their technical support.
- M. tuberculosis
- Mucosal vaccine
- Salmonella vector