Cutinase-like protein-6 of Mycobacterium tuberculosis is recognised in tuberculosis patients and protects mice against pulmonary infection as a single and fusion protein vaccine

Infection with Mycobacterium tuberculosis continues to be a leading cause of death in many regions of the world, and control of this disease is hampered by the lack of a safe and effective vaccine. Secreted proteins of M. tuberculosis are an important group of antigens for subunit vaccines which target this infection. We have tested three secreted members of the cutinase-like protein (CULP) family of M. tuberculosis for their potential as protein vaccine antigens. Culp6 elicited a strong T lymphocyte response in M. tuberculosis infected mice, and importantly, in tuberculosis (TB) patients tested. Culp1, Culp2 and Culp6 when delivered as protein vaccines to mice, induced potent IFN-γ responses which in turn translated into a significant level of protection against aerosol M. tuberculosis infection. A Culp1–6 fusion protein provided an increased level of protection against infection compared to Culp1 or Culp6 alone. The data presented here may indicate that the cell wall-associated, putatively essential protein Culp6, shown here for the first time to be recognised in TB patients, is an attractive candidate for inclusion in future subunit vaccines.