Dataset Information

Protective Efficacy of Inhaled BCG Vaccination Against Ultra-Low Dose Aerosol M. tuberculosis Challenge in Rhesus Macaques.

ABSTRACT: Ten million cases of tuberculosis (TB) were reported in 2018 with a further 1.5 million deaths attributed to the disease. Improved vaccination strategies are urgently required to tackle the ongoing global TB epidemic. In the absence of a validated correlate of protection, highly characterised pre-clinical models are required to assess the protective efficacy of new vaccination strategies. In this study, we demonstrate the application of a rhesus macaque ultra-low dose (ULD) aerosol M. tuberculosis challenge model for the evaluation of TB vaccination strategies by directly comparing the immunogenicity and efficacy of intradermal (ID) and aerosol BCG vaccination delivered using a portable vibrating mesh nebulizer (VMN). Aerosol- and ID-delivered Bacille Calmette-Guérin (BCG) induced comparable frequencies of IFN-? spot forming units (SFU) measured in peripheral blood mononuclear cells (PBMCs) by ELISpot, although the induction of IFN-? SFU was significantly delayed following aerosol immunisation. This delayed response was also apparent in an array of secreted pro-inflammatory and chemokine markers, as well as in the frequency of antigen-specific cytokine producing CD4 and CD8 T-cells measured by multi-parameter flow cytometry. Interrogation of antigen-specific memory T-cell phenotypes revealed that vaccination-induced CD4 and CD8 T-cell populations primarily occupied the central memory (TCM) and transitional effector memory (TransEM) phenotype, and that the frequency of CD8 TCM and TransEM populations was significantly higher in aerosol BCG-vaccinated animals in the week prior to M. tuberculosis infection. The total and lung pathology measured following M. tuberculosis challenge was significantly lower in vaccinated animals relative to the unvaccinated control group and pathology measured in extra-pulmonary tissues was significantly reduced in aerosol BCG-vaccinated animals, relative to the ID-immunised group. Similarly, significantly fewer viable M. tuberculosis CFU were recovered from the extra-pulmonary tissues of aerosol BCG-vaccinated macaques relative to unvaccinated animals. In this study, a rhesus macaque ULD M. tuberculosis aerosol challenge model was applied as a refined and sensitive system for the evaluation of TB vaccine efficacy and to confirm that aerosol BCG vaccination delivered by portable VMN can confer a significant level of protection that is equivalent, and by some measures superior, to intradermal BCG vaccination.

SUBMITTER: White AD

PROVIDER: S-EPMC7284565 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Protective Efficacy of Inhaled BCG Vaccination Against Ultra-Low Dose Aerosol <i>M. tuberculosis</i> Challenge in Rhesus Macaques.

White Andrew D AD Sarfas Charlotte C Sibley Laura S LS Gullick Jennie J Clark Simon S Rayner Emma E Gleeson Fergus F Català Martí M Nogueira Isabel I Cardona Pere-Joan PJ Vilaplana Cristina C Dennis Mike J MJ Williams Ann A Sharpe Sally A SA

Pharmaceutics 20200425 5

Ten million cases of tuberculosis (TB) were reported in 2018 with a further 1.5 million deaths attributed to the disease. Improved vaccination strategies are urgently required to tackle the ongoing global TB epidemic. In the absence of a validated correlate of protection, highly characterised pre-clinical models are required to assess the protective efficacy of new vaccination strategies. In this study, we demonstrate the application of a rhesus macaque ultra-low dose (ULD) aerosol <i>M. tubercu ...[more]

PMID: 32344890

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Project description:Mycobacterium tuberculosis infects approximately one-third of the world's population, causing active tuberculosis (TB) in ~10 million people and death in ~1.5 million people annually. A potent vaccine is needed to boost the level of immunity conferred by the current Mycobacterium bovis BCG vaccine that provides moderate protection against childhood TB but variable protection against adult pulmonary TB. Previously, we developed a recombinant attenuated Listeria monocytogenes (rLm)-vectored M. tuberculosis vaccine expressing the M. tuberculosis 30-kDa major secretory protein (r30/Ag85B), recombinant attenuated L. monocytogenes ΔactA ΔinlB prfA*30 (rLm30), and showed that boosting BCG-primed mice and guinea pigs with rLm30 enhances immunoprotection against challenge with aerosolized M. tuberculosis Erdman strain. To broaden the antigen repertoire and robustness of rLm30, we constructed 16 recombinant attenuated L. monocytogenes vaccine candidates expressing 3, 4, or 5 among 15 selected M. tuberculosis antigens, verified their protein expression, genetic stability, and growth kinetics in macrophages, and evaluated them for capacity to boost protective efficacy in BCG-primed mice. We found that boosting BCG-primed C57BL/6 and BALB/c mice with recombinant attenuated L. monocytogenes multiantigenic M. tuberculosis vaccines, especially the rLm5Ag(30) vaccine expressing a fusion protein of 23.5/Mpt64, TB10.4/EsxH, ESAT6/EsxA, CFP10/EsxB, and r30, enhances BCG-induced protective immunity against M. tuberculosis aerosol challenge. In immunogenicity studies, rLm5Ag(30) strongly boosts M. tuberculosis antigen-specific CD4-positive (CD4+) and CD8+ T cell-mediated TH1-type immune responses in the spleens and lungs of BCG-primed C57BL/6 mice but does so only weakly in BCG-primed BALB/c mice. Hence, rLm5Ag(30) boosts BCG-primed immunoprotection against M. tuberculosis aerosol challenge in both C57BL/6 and BALB/c mice despite major differences in the magnitude of the vaccine-induced Th1 response in these mouse strains. Given the consistency with which recombinant attenuated L. monocytogenes vaccines expressing the 5 M. tuberculosis antigens in rLm5Ag(30) are able to boost the already high level of protection conferred by BCG alone in two rigorous mouse models of pulmonary TB and the broad CD4+ and CD8+ T cell immunity induced by rLm5Ag(30), this vaccine holds considerable promise as a new vaccine to combat the TB pandemic, especially for the majority of the world's population immunized with BCG in infancy. IMPORTANCE TB, one of the world's most important infectious diseases, afflicts approximately 10 million people and kills approximately 1.5 million people annually. The current vaccine, BCG, developed over a century ago, has been administered to about 5 billion people, mostly in infancy, but is only modestly protective. Hence, a vaccine is urgently needed to boost the level of protection afforded by BCG. Herein, we describe a safe potent live vaccine that utilizes as a vector an attenuated strain of Listeria monocytogenes, a bacterium that mimics the intracellular lifestyle of Mycobacterium tuberculosis, the causative agent of TB. The vaccine produces multiple immunologically protective proteins of M. tuberculosis. In two mouse models of pulmonary TB, the vaccine boosts the level of protection afforded by BCG. Thus, this vaccine holds considerable promise as a new vaccine to combat the TB pandemic, especially for the majority of the world's population immunized with BCG.

Dataset Information

Protective Efficacy of Inhaled BCG Vaccination Against Ultra-Low Dose Aerosol M. tuberculosis Challenge in Rhesus Macaques.

Publications

Protective Efficacy of Inhaled BCG Vaccination Against Ultra-Low Dose Aerosol <i>M. tuberculosis</i> Challenge in Rhesus Macaques.

Similar Datasets

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