Increased vaccine efficacy against tuberculosis of recombinant Mycobacterium bovis bacille Calmette-Guérin mutants that secrete listeriolysin
Leander Grode, Peter Seiler, Sven Baumann, Jürgen Hess, Volker Brinkmann, Ali Nasser Eddine, Peggy Mann, Christian Goosmann, Silke Bandermann, Debbie Smith, Gregory J. Bancroft, Jean-Marc Reyrat, Dick van Soolingen, Bärbel Raupach, Stefan H.E. Kaufmann
Leander Grode, Peter Seiler, Sven Baumann, Jürgen Hess, Volker Brinkmann, Ali Nasser Eddine, Peggy Mann, Christian Goosmann, Silke Bandermann, Debbie Smith, Gregory J. Bancroft, Jean-Marc Reyrat, Dick van Soolingen, Bärbel Raupach, Stefan H.E. Kaufmann
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Research Article Infectious disease

Increased vaccine efficacy against tuberculosis of recombinant Mycobacterium bovis bacille Calmette-Guérin mutants that secrete listeriolysin

Abstract

The tuberculosis vaccine Mycobacterium bovis bacille Calmette-Guérin (BCG) was equipped with the membrane-perforating listeriolysin (Hly) of Listeria monocytogenes, which was shown to improve protection against Mycobacterium tuberculosis. Following aerosol challenge, the Hly-secreting recombinant BCG (hly+ rBCG) vaccine was shown to protect significantly better against aerosol infection with M. tuberculosis than did the parental BCG strain. The isogenic, urease C–deficient hly+ rBCG (ΔureC hly+ rBCG) vaccine, providing an intraphagosomal pH closer to the acidic pH optimum for Hly activity, exhibited still higher vaccine efficacy than parental BCG. ΔureC hly+ rBCG also induced profound protection against a member of the M. tuberculosis Beijing/W genotype family while parental BCG failed to do so consistently. Hly not only promoted antigen translocation into the cytoplasm but also apoptosis of infected macrophages. We concluded that superior vaccine efficacy of ΔureC hly+ rBCG as compared with parental BCG is primarily based on improved cross-priming, which causes enhanced T cell–mediated immunity.

Authors

Leander Grode, Peter Seiler, Sven Baumann, Jürgen Hess, Volker Brinkmann, Ali Nasser Eddine, Peggy Mann, Christian Goosmann, Silke Bandermann, Debbie Smith, Gregory J. Bancroft, Jean-Marc Reyrat, Dick van Soolingen, Bärbel Raupach, Stefan H.E. Kaufmann

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Antigen presence in the cytosol. (A–D) Bone marrow macrophages infected ...
Antigen presence in the cytosol. (A–D) Bone marrow macrophages infected for 24 hours with ΔureC hly+ rBCG (A and B) and parental BCG (C and D). The images are projections of 2 confocal planes from specimens stained for BCG (green), F-actin (red), and DNA (blue) (overlay in A and C). Material stained with an antibody raised against BCG is dispersed throughout the cytoplasm in cells infected with ΔureC hly+ rBCG while BCG material is exclusively located in bacteria within cells infected with parental BCG. Scale bar in A–D: 10 μm. (E and F) Fine structural analysis of mycobacterial localization in bone marrow macrophages 24 hours after infection with ΔureC hly+ rBCG (E) and parental BCG (F). Panel E shows strong staining of a bacterium in a phagosome; additional staining for mycobacterial material was found in the cytoplasm (indicated by an arrow). However, cytoplasmic staining was greatly reduced in cells infected with parental BCG (F). Quantification of the density of immunogold signal in the cytoplasm of infected cells: parental BCG, 3.5 ± 2.3 gold particles/μm2; ΔureC hly+ rBCG, 7.0 ± 3.7 gold particles/μm2; P = 0.022 (Mann-Whitney U test). Scale bar in E and F: 1 μm.