SapM mutation to improve the BCG vaccine: Genomic, transcriptomic and preclinical safety characterization

Festjens, Nele; Vandewalle, Kristof; Houthuys, Erica; Plets, Evelyn; Vanderschaeghe, Dieter; Borgers, Katlyn; Hecke, Annelies Van; Tiels, Petra; Callewaert, Nico

doi:10.1016/j.vaccine.2019.05.022

Cited by 14 publications

(15 citation statements)

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“…SapM is a secreted acid phosphatase of M. tb and has an important role in immunomodulation [36]. Interestingly, recent work on a sapM transposon mutant of BCG (sapM::Tn BCG) demonstrates better innate control compared to the parental BCG strain, including more rapid recruitment of dendritic cells (DCs) to draining lymphoid organs [36]. The sapM::Tn BCG also shows potential as an improved subcutaneous BCG vaccine, increasing long-term survival of M. tb H37Rv infected mice [38].…”

Section: Rbcgs Modulating Immunogenicitymentioning

confidence: 99%

“…The sapM::Tn BCG also shows potential as an improved subcutaneous BCG vaccine, increasing long-term survival of M. tb H37Rv infected mice [38]. Only a brief investigation of TB-specific IFNγ producing CD4 + and CD8 + T cells 2 weeks post-vaccination was conducted; further study of the related adaptive immune response to sapM::Tn BCG is required [36]. However, this study brings up the question of whether innate immune control may play a larger role than previously considered in protective immunity to TB, a phenomenon that is typically connected to viral infections [39,40].…”

Section: Rbcgs Modulating Immunogenicitymentioning

confidence: 99%

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Preclinical Progress of Subunit and Live Attenuated Mycobacterium tuberculosis Vaccines: A Review following the First in Human Efficacy Trial

Watt

Liu

2020

Pharmaceutics

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Tuberculosis (TB) is the global leading cause of death from an infectious agent with approximately 10 million new cases of TB and 1.45 million deaths in 2018. Bacille Calmette-Guérin (BCG) remains the only approved vaccine for Mycobacterium tuberculosis (M. tb, causative agent of TB), however clinical studies have shown BCG has variable effectiveness ranging from 0–80% in adults. With 1.7 billion people latently infected, it is becoming clear that vaccine regimens aimed at both post-exposure and pre-exposure to M. tb will be crucial to end the TB epidemic. The two main strategies to improve or replace BCG are subunit and live attenuated vaccines. However, following the failure of the MVA85A phase IIb trial in 2013, more varied and innovative approaches are being developed. These include recombinant BCG strains, genetically attenuated M. tb and naturally attenuated mycobacteria strains, novel methods of immunogenic antigen discovery including for hypervirulent M. tb strains, improved antigen recognition and delivery strategies, and broader selection of viral vectors. This article reviews preclinical vaccine work in the last 5 years with focus on those tested against M. tb challenge in relevant animal models.

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Section: Rbcgs Modulating Immunogenicitymentioning

confidence: 99%

Section: Rbcgs Modulating Immunogenicitymentioning

confidence: 99%

Preclinical Progress of Subunit and Live Attenuated Mycobacterium tuberculosis Vaccines: A Review following the First in Human Efficacy Trial

Watt

Liu

2020

Pharmaceutics

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“…Even after almost 100 years of use, the BCG vaccine has been the focus of recent studies to improve its protection. Current strategies range from alternative routes of BCG administration (Darrah et al, 2020) to genetic manipulation (Festjens et al, 2019). Intravenous immunization with BCG in macaques was shown to induce more T cells antigen-responses when compared to the common intradermal administration route, protecting these animals against M. tuberculosis challenge after 6 months of vaccination (Darrah et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Handling the Hurdles on the Way to Anti-tuberculosis Drug Development

et al. 2020

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The global epidemic of tuberculosis (TB) imposes a sustained epidemiologic vigilance and investments in research by governments. Mycobacterium tuberculosis, the main causative agent of TB in human beings, is a very successful pathogen, being the main cause of death in the population among infectious agents. In 2018, ∼10 million individuals were contaminated with this bacillus and became ill with TB, and about 1.2 million succumbed to the disease. Most of the success of the M. tuberculosis to linger in the population comes from its ability to persist in an asymptomatic latent state into the host and, in fact, the majority of the individuals are unaware of being contaminated. Even though TB is a treatable disease and is curable in most cases, the treatment is lengthy and laborious. In addition, the rise of resistance to first-line anti-TB drugs elicits a response from TB research groups to discover new chemical entities, preferably with novel mechanisms of action. The pathway to find a new TB drug, however, is arduous and has many barriers that are difficult to overcome. Fortunately, several approaches are available today to be pursued by scientists interested in anti-TB drug development, which goes from massively testing chemical compounds against mycobacteria, to discovering new molecular targets by genetic manipulation. This review presents some difficulties found along the TB drug development process and illustrates different approaches that might be used to try to identify new molecules or targets that are able to impair M. tuberculosis survival.

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“…This is mainly due to the presence of transcriptionally active transposon-associated sequences, especially an antibiotic selection marker, increasing the risk for polar effects. We have recently observed such an effect in a vaccine research project in our lab, where transposon insertion in the sapM gene resulted in a strong enhancement of expression of the upstream upp gene, necessitating a significant effort in complementation experiments and laborious generation of a 'clean' sapM knockout (KO) to exclude a role for this Upp upregulation in the observed enhanced vaccine efficacy of sapM mutation in BCG (9). Presence of antibiotic selection markers also precludes the use of such transposon mutants for further (pre)clinical development as vaccines.…”

Section: Introductionmentioning

confidence: 99%

Use of a counterselectable transposon to create markerless knockouts from a 18,432-clone orderedM. bovisBCG mutant resource

Borgers

Vandewalle

Hecke

et al. 2019

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Mutant resources are essential to improve our understanding of the biology of slow-growing mycobacteria, which include the causative agents of tuberculosis in various species, including humans. The generation of deletion mutants in slow-growing mycobacteria in a gene-by-gene approach in order to make genome-wide ordered mutant resources is still a laborious and costly approach; despite the recent development of improved methods. On the other hand, transposon mutagenesis in combination with Cartesian Pooling-Coordinate Sequencing allows the creation of large archived Mycobacterium transposon insertion libraries. However, such mutants contain selection marker genes with a risk of polar gene effects, which is undesired both for research and for use of these mutants as live attenuated vaccines. In this paper, a derivative of the Himar1 transposon is described, which allows the generation of clean, markerless knockouts from archived transposon libraries. By incorporating FRT sites for FlpE/FRT-mediated recombination and I-SceI sites for ISceIM-based transposon removal, we enable two thoroughly experimentally validated possibilities to create unmarked mutants from such marked transposon mutants. The FRT approach Page 2 of 24 is highly efficient but leaves an FRT scar in the genome, whereas the I-SceI mediated approach can create mutants without any heterologous DNA in the genome. The combined use of CP-CSeq and this optimized transposon was applied in the BCG Danish 1331 vaccine strain (WHO reference 07/270), creating the largest ordered, characterized resource of mutants in a member of the M. tb complex (18,432 clones, mutating 83% of the non-essential M. tb homologues), from which clean knockouts can be generated. Importance:While speeding up research for many fields of biology (e.g. yeast, plant, and C. elegans), genomewide ordered mutant collections are still elusive in mycobacterial research. We developed methods to generate such resources in a time-and cost-effective manner, and developed a newly engineered transposon from which unmarked mutants can be efficiently generated. Our library in the WHO reference vaccine strain of M. bovis BCG Danish targets 83% of all non-essential genes and was made publicly available via the BCCM/ITM Mycobacteria Collection. This resource will speed up Mycobacterium research (e.g. drug resistance research, vaccine development) and paves the way to similar genome-wide mutant collections in other strains of the M. tb complex. The stretch to a full collection of mutants in all non-essential genes is now much shorter, with just 17% remaining genes to be targeted using gene-by-gene approaches, for which highly effective methods have recently also been described. MAIN TEXT:

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SapM mutation to improve the BCG vaccine: Genomic, transcriptomic and preclinical safety characterization

Abstract: SapM mutation to improve the BCG vaccine: genomic, transcriptomic and preclinical safety characterization

Cited by 14 publications

References 53 publications

Preclinical Progress of Subunit and Live Attenuated Mycobacterium tuberculosis Vaccines: A Review following the First in Human Efficacy Trial

Preclinical Progress of Subunit and Live Attenuated Mycobacterium tuberculosis Vaccines: A Review following the First in Human Efficacy Trial

Handling the Hurdles on the Way to Anti-tuberculosis Drug Development

Use of a counterselectable transposon to create markerless knockouts from a 18,432-clone orderedM. bovisBCG mutant resource

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