Poster Presentation Australasian Society for Immunology Annual Scientific Meeting 2014

Targeting immunogenic peptides from Mycobacterium tuberculosis to TLR2 for use as pulmonary vaccines (#338)

Anneliese Ashhurst 1 , Leon Lin 1 , Santosh Rudrawar 2 , Nicholas West 3 , Richard Payne 2 , Warwick Britton 1 4
  1. Tuberculosis Research Program, Centenary Institute, Sydney, NSW, Australia
  2. School of Chemistry, University of Sydney, Sydney, NSW, Australia
  3. School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
  4. Sydney Medical School, University of Sydney, Sydney, NSW, Australia

Tuberculosis (TB) remains a staggering burden on global health, with more effective vaccines needed to improve TB control. Recent clinical trials of an MVA-based vaccine for TB were non-protective when delivered by the intra-dermal route. Interestingly, pulmonary delivery improved localised immune responses in the BAL, offering potential for improved protection. However, the use of live viruses as vectors for aerosol delivery poses significant safety concerns. We are therefore developing strategies for pulmonary protein-based vaccination, a safer alternative that aims to induce local immune responses in the pulmonary mucosa as well as systemic responses.  Peptides from immuno-dominant antigens of Mycobacterium tuberculosis were synthesised and covalently conjugated to the TLR2-ligand Pam2Cys, providing antigen to immune cells in a self-adjuvanting context. We utilised the p25 peptide from Ag85B, and the TB10.43-11 peptide from TB10.4, major CD4 and CD8 epitopes respectively in C57BL/6 mice. The Pam2Cys-peptide conjugate activated TLR2 in vitro as expected. Antigen-specific immune responses were compared after either sub-cutaneous or intra-nasal delivery of the conjugate to mice. Delivery by either route induced modest antigen-specific IFNγ responses in the spleen, however this was increased in mice receiving intra-nasal immunisation. We noted greatly increased numbers of antigen-specific, IFNγ-secreting cells in the lungs and mediastinal lymph node of mice immunised intra-nasally. In addition, we noted significant IL17+, TNFα+, or double IL17+TNFα+ producing populations of p25 specific CD4+ T-lymphocytes in the lungs of intra-nasally immunised mice. There was a strong IFNγ and TNFα response observed from TB10.43-11 specific CD8+ T-lymphocytes. These populations were absent in the spleens of sub-cutaneously immunised mice, suggesting that mucosal delivery of the conjugate vaccine enhances immunogenicity. The combination of TLR2-targeting and pulmonary vaccine formulation to enhance localised immune responses, is a potential strategy for vaccination against M. tuberculosis.