In this system, DDA targets the vaccine antigen to APCs while TDB provides proinflammatory stimuli, triggering a Th-1 cytokine response via a TLR-independent pathway (Agger et al., 2008). CAF01 has proven to be highly efficacious, inducing cellular and humoral responses simultaneously in animal models more effectively than the single antigens administered alone. In addition to its priming activity, this vaccine has also been demonstrated to have a BCG booster effect (Doherty et al., 2004; Davidsen et al., 2005). AS01B, developed by Corixa

and GlaxoSmithKline Lumacaftor in vivo Biologicals, contains the TLR4 ligand MPL and the saponin derivative QS-21 in a liposomal formulation including the fusion molecule Mtb72F. The Mtb72F antigen is comprised of the PPE family member Rv1196 inserted into the middle HSP signaling pathway of the putative serine protease Rv0125, which is thus present as two fragments (Mtb32C–Mtb39–Mtb32N) (Skeiky et al., 2004). In the AS01B or AS02A formulations, this vaccine has also been demonstrated to have priming and BCG booster effects (Brandt et al.,

2004). IC31, also developed by the Statens Serum Institute, consists of a vehicle combining the synthetic antimicrobial peptide KLKL5KLK, which actively loads APCs with antigen, and the immunostimulatory TLR9 ligand ODN1a, with the fusion proteins H1 and Ag85B–TB10.4 (Agger et al., 2006; Lingnau et al., 2007). This vaccine confers protective immunity in murine tuberculosis models and was recently shown to safely induce strong T-cell responses with a mixed Th-1/Th-2 cytokine profile in both neonates and adults (Kamath et al., 2008). CAF01, AS01B and IC31 are currently undergoing clinical Phase I/II trials. Mtb72F/AS01B is being tested in Lausanne, Switzerland, in individuals previously check details exposed to BCG or previously treated individuals

currently infected with Mtb. H1 in IC31 and CAF01 are being tested in Leiden, the Netherlands, in purified protein derivative (PPD)-negative subjects. These adjuvants share the same basic combination of a delivery vehicle and a Th-1-skewing immunomodulator, conferring more potent protection against tuberculosis infection than single immunomodulators (CpG or MPL) or delivery vehicles lacking immunomodulators (liposomes or niosomes) (Agger et al., 2006). LTK63, a modified and detoxified heat-labile toxin derived from E. coli, has been combined with the fusion protein H1 for nasal immunization and has passed Phase I clinical trials (in London, UK, with PPD-negative subjects). A strong and sustained Th-1 response mediated by IFN-γ-secreting CD4+ T cells was observed, leading to long-lasting protection against tuberculosis and boosting prior BCG-induced immunity (Dietrich et al., 2006; Badell et al., 2009).