Mycobacterium tuberculosis-secreted protein antigens: Immunogenicity in baboons

The effective control of tuberculosis (TB) requires the development of impr oved vaccines. It is now well established that Mycobacterium tuberculosis-s ecreted antigens represent promising candidates to be included in subunit v accine preparations. It also is accepted that studies in nonhuman primate m odels will be required to further develop these vaccine preparations. As a necessary step in this direction, we have assessed the immunogenicity of M. tuberculosis-secreted antigens in baboons. Animals received a total of thr ee intramuscular injections consisting of M. tuberculosis culture filtrate proteins resuspended in an adjuvant formulation (MPL-SE) and were tested fo r development of specific antibody and cellular responses. All animals prod uced antibody and cellular proliferative responses in the absence of detect able delayed-type hypersensitivity reactions. Production of gamma-interfero n following stimulation of peripheral blood lymphocytes with culture filtra te proteins was either absent or present at low levels. Results from this s tudy show that, although M. tuberculosis-secreted protein antigens are rela tively safe and immunogenic in baboons, alternative immunization approaches must be identified for the induction of T-helper type 1 responses.