<i>Mycobacterium</i> Growth Inhibition Assay of Human Alveolar Macrophages as a Correlate of Immune Protection Following Mycobacterium bovis Bacille Calmette-Guérin Vaccination

Background In order to eliminate tuberculosis (TB), an effective vaccine is urgently needed to prevent infection with Mycobacterium tuberculosis . A key obstacle for the development of novel TB vaccines is the lack of surrogate markers for immune protection against M. tuberculosis . Methods We investigated growth rates of M. tuberculosis in the mycobacterial growth inhibition assay (MGIA) as a marker for mycobacterial growth control of human bronchoalveolar lavage (BALC) and peripheral blood mononuclear cells (PBMC) before and after vaccination with Mycobacterium bovis Bacille Calmette-Guérin (BCG) of healthy adult volunteers. Results Vaccination induced a positive response ( p M. bovis BCG-vaccination revealed no significant difference in time to culture positivity before and after vaccination in BALC ( p = 0.604) and PBMC ( p = 0.199). The magnitude of the PPD-response induced by M. bovis BCG-vaccination did not correlate with growth control in BALC and PBMC (correlation = 0.468, 95% CI: -0.016 to 0.775). Conclusion In conclusion, M. bovis BCG-vaccination-induced mycobacterial-specific cytokine immune response does not result in functional immune control against M. tuberculosis in the MGIA.