The present project combines state-of-the-art research in ISCOMS- and toxin- based adjuvants, with expertise in Mycobacterial infections and vaccine design. By incorporating the enzymatically active cholera toxin derived CTA1-DD immunoenhancer into ISCOMS, the consortium has obtained an adjuvant with synergistic effects compared to either adjuvant used alone. This promising adjuvant technology will now be explored in a mucosal tuberculosis (TB) vaccine. The partners are at the forefront of this expanding field of research and propose to identify the function of this new adjuvant at the cellular and molecular level. Its immunogenicity will be analysed for mucosal and systemic immune responses and its potential determined for stimulating TB-specific protective immunity following mucosal immunisation. The study will result in a better understanding of adjuvant functions and how to optimally design mucosal vaccines and TB-specific vaccines in particular.
The work has been divided into six interacting work-packages. The first covers the construction of the CTA1-DD vectors, with or without the TB hybrid molecule, Ag85b-ESAT6 or peptide. For comparative studies the consortium will also construct CTA1-DD fusion proteins or conjugates containing ovalbumin or its well-defined class I and II restricted peptide sequences, p 323-339 and 257-263 respectively. In the absence of well-defined TB-specific protective epithopes, the latter will be used in gene-knockout and transgenic mice to reflect conditions required for induction of TB-specific protective immunity. Constructs based on the inactive mutant CTA1R7K-DD will be used to assess the contribution of the ADP-ribosylating enzyme to the adjuvant function of the CTA1-DD-ISCOMS. In the second work package, the ISCOM-technology will be refined to optimise mucosal adjuvanticity of CTA1-DD-ISCOMS carrying the TB hybrid molecule, Af85b-ESAT6 or peptides thereof. Several combinations of selected fractions QV-A, QV-B and QV-C represent various peaks of the Quillaja saponin spectrum with unique and distinct activities. The third and fourth work packages will use the constructs 1 and 2 to investigate the immunogenic effects and address the mechanisms of adjuvanticity of the CTA1-DD-ISCOMS-TB/OVA constructs. The project’s CTA1-DD-ISCOMS TB vaccine will be studied in detail to see how it interacts with professional APC (macrophages, DC and B cells) to induce active immunity via mucosal surfaces using transgenic and gene-knockout mice. The fifth workpackage will explore whether mucosal immunisation with CTA1-DD-ISCOMS-TB vaccine candidate can stimulate immune protection against a live challenge infection with M. tuberculosis. The final work package will describe properties of TB-specific, long-term memory calls after successful immunisation with the CTA1-DD-ISCOMS TB vaccine.
Department of Clinical Immunology
413 46 Goeteborg
Tel: +46 31 342 4936
Fax: +46 31 827 647