Co-administration of a synthetic saccharide conjugate vaccine with BCG provides synergistic protection against murine tuberculosis.

Tuberculosis (TB) remains a major global health challenge claiming over 1 million lives annually. Bacillus Calmette-Guérin (BCG), the only licensed vaccine against TB, provides limited efficacy against pulmonary TB in adults and only partial protection against serious disease in children. Hence, the development of safer and more effective new vaccines against TB remains a global health priority. Here we show in a new approach that co-administration of BCG with a novel synthetic glycan conjugate vaccine, corresponding to conserved terminal mannose sequences in Phosphatidyl-myo-inositol-mannosides (PIMs) in the cell envelope of mycobacteria, results in reduced bacterial burden compared to BCG vaccination alone. This first in vivo efficacy study suggests that targeting conserved essential oligosaccharides of mycobacteria is an important factor in improving TB vaccine efficacy.