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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Increased apoptosis of infected macrophages. Primary human (A) and murin...
Increased apoptosis of infected macrophages. Primary human (A) and murine (B) macrophages were infected with hly+ rBCG (filled triangles), ΔureC hly+ rBCG (circles), parental BCG (open triangles), or ΔureC rBCG (open squares), or left uninfected (filled squares). After different periods of time, apoptotic cell death was determined by measurement of DNA-fragmentation according to ref. 43. Statistical analyses resulted in values of P < 0.05 in A and P < 0.001 in B for ΔureC hly+ rBCG compared with parental BCG over the whole observation period. Shown is 1 out of 3 independent experiments each. (C–E) After 24 hours of infection with ΔureC hly+ rBCG (C), about 45% of bone marrow macrophages underwent apoptosis as revealed by a positive TUNEL assay while only 6% of BCG-infected macrophages (D) were apoptotic. Scale bar: 40 μm. (E) Quantification of the TUNEL assay: blue, BCG positive; pink, BCG negative.