Bacillus subtilis spores as adjuvants for DNA vaccines

Vaccine. 2015 May 11;33(20):2328-34. doi: 10.1016/j.vaccine.2015.03.043. Epub 2015 Mar 27.


Recently, Bacillus subtilis spores were shown to be endowed with strong adjuvant capacity when co-administered with purified antigenic proteins. In the present study we assessed whether spores possess adjuvant properties when combined with DNA vaccines. We showed that B. subtilis spores promoted the activation of dendritic cells in vitro and induced migration of pro-inflammatory cells after parenteral administration to mice. Likewise, co-administration of spores with a DNA vaccine encoding the human papillomavirus type 16 (HPV-16) E7 protein enhanced the activation of antigen-specific CD8(+) T cell responses in vivo. Mice immunized with the DNA vaccine admixed with spores presented a protective immunity increase to previously implanted tumor cells, capable of expressing HPV-16 oncoproteins. Finally, we observed that the adjuvant effect can vary accordingly to the number of co-administered spores which may be ascribed with the ability to induce. Collectively, the present results demonstrate for the first time that B. subtilis spores can also confer adjuvant effects to DNA vaccines.

Keywords: Adjuvants; Bacillus subtilis; DNA vaccine; HPV-16; Spores.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / administration & dosage*
  • Animals
  • Bacillus subtilis / immunology*
  • Bacillus subtilis / physiology
  • CD8-Positive T-Lymphocytes / immunology
  • Cell Line, Tumor
  • Cytokines / immunology
  • Dendritic Cells / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Interferon-gamma / immunology
  • Male
  • Mice, Inbred C57BL
  • Papillomavirus E7 Proteins / genetics
  • Papillomavirus E7 Proteins / immunology
  • Spores, Bacterial / immunology*
  • Vaccines, DNA / administration & dosage
  • Vaccines, DNA / immunology*


  • Adjuvants, Immunologic
  • Cytokines
  • Papillomavirus E7 Proteins
  • Vaccines, DNA
  • oncogene protein E7, Human papillomavirus type 16
  • Interferon-gamma