Strategies for developing tuberculosis vaccines: emerging approaches.

The current vaccine against TB, bacille Calmette-Guèrin (BCG) fails to protect against the most prevalent disease form, the pulmonary TB in adults. Thus, it is not a satisfactory vaccine. Given that T cells are central to protection against TB, future vaccine design should focus on T-lymphocyte populations. Most vaccines do not prevent infection but instead disease, that if they allow establishment of the pathogen in the host but prevent its harmful effects. The development of synthetic peptide-based immunogens is emerging as a possible approach in human vaccination in the future, as a replacement for conventional vaccines that use killed or attenuated whole microorganisms. The advantages of such synthetic vaccines (high potency, low adverse reactions, low cross-reactivity and high stability) are offset somewhat by the poorer inherent immunogenicity of these constructs. There is a greater need therefore to develop adjuvant/carrier systems to increase the immunogenicity of these newer vaccine candidates.