Multiple comparison of dried BCG vaccines: stability at 37°C and persistence of strains in the mouse spleen

Lugosi, L

doi:10.1016/0264-410x(84)90007-0

Cited by 8 publications

(4 citation statements)

References 10 publications

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“…The question of BCG persistence has been noted in previous studies in mice [24,25,27,[32][33][34][35], other animal models [23,26] and humans [36,37]. In a similar study using C57BL/6 mice and M. tb challenge [27], spleen protection was reduced by 75%, but in contrast lung immunity was unaffected.…”

Section: Discussionmentioning

confidence: 72%

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Persistent BCG bacilli perpetuate CD4 T effector memory and optimal protection against tuberculosis

Kaveh

García-Pelayo

Hogarth

2014

Vaccine

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Tuberculosis (TB) remains one of the most important infectious diseases of man and animals, and the only available vaccine (BCG) requires urgent replacement or improvement. To facilitate this, the protective mechanisms induced by BCG require further understanding. As a live attenuated vaccine, persistence of BCG bacilli in the host may be a crucial mechanism. We have investigated the long term persistence of BCG following vaccination and the influence on the induced immune response and protection, using an established murine model. We sought to establish whether previously identified BCG-specific CD4 TEM cells represent genuine long-lived memory cells of a relatively high frequency, or are a consequence of continual priming by chronically persistent BCG vaccine bacilli. By clearing persistent bacilli, we have compared immune responses (spleen and lung CD4: cytokine producing T effector/TEM; TCR-specific) and BCG-induced protection, in the presence and absence of these persisting vaccine bacilli. Viable BCG bacilli persisted for at least 16 months post-vaccination, associated with specific CD4 T effector/TEM and tetramer-specific responses. Clearing these bacilli abrogated all BCG-specific CD4 T cells whilst only reducing protection by 1log10. BCG may induce two additive mechanisms of immunity: (i) dependant on the presence of viable bacilli and TEM; and (ii) independent of these factors. These data have crucial implications on the rational generation of replacement TB vaccines, and the interpretation of BCG induced immunity in animal models.

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Section: Discussionmentioning

confidence: 72%

“…Given the potential of BCG to persist in the immuno-competent host [23][24][25][26][27], combined with the absence of immune contraction; we hypothesised whether these CD4 T EM cells represent: (a) genuine long-lived high frequency memory cells, or alternately; (b) result from continual priming by persistent BCG bacilli.…”

Section: Introductionmentioning

confidence: 99%

Persistent BCG bacilli perpetuate CD4 T effector memory and optimal protection against tuberculosis

Kaveh

García-Pelayo

Hogarth

2014

Vaccine

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“…We evaluated the combined impact of three cryoprotectant solutions at different temperatures, compared with MSG, which has been shown to have the highest effectiveness on the stability of the vaccine [ 34 , 35 ]. Vaccine containing 1% MSG was characterised by best thermostability, homogeneity, and the high survival of bacilli during freeze-drying [ 9 , 36 , 37 , 38 , 39 ]. Wong et al, in 2007 [ 40 ], demonstrated that BCG suspended in 1.5% MSG could be dried without freezing, through spray drying, and maintained stably at room-temperature for several months.…”

Section: Discussionmentioning

confidence: 99%

Optimisation of Mycobacterium bovis BCG Fermentation and Storage Survival

et al. 2020

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Mycobacterium bovis Bacillus Calmette–Guérin (M. bovis BCG) was generated over a century ago for protection against Mycobacterium tuberculosis (Mtb) and is one the oldest vaccines still in use. The BCG vaccine is currently produced using a pellicle growth method, which is a complex and lengthy process that has been challenging to standardise. Fermentation for BCG vaccine production would reduce the complexity associated with pellicle growth and increase batch to batch reproducibility. This more standardised growth lends itself to quantification of the total number of bacilli in the BCG vaccine by alternative approaches, such as flow cytometry, which can also provide information about the metabolic status of the bacterial population. The aim of the work reported here was to determine which batch fermentation conditions and storage conditions give the most favourable outcomes in terms of the yield and stability of live M. bovis BCG Danish bacilli. We compared different media and assessed growth over time in culture, using total viable counts, total bacterial counts, and turbidity throughout culture. We applied fluorescent viability dyes and flow cytometry to measure real-time within-culture viability. Culture samples were stored in different cryoprotectants at different temperatures to assess the effect of these combined conditions on bacterial titres. Roisin’s minimal medium and Middlebrook 7H9 medium gave comparable, high titres in fermenters. Flow cytometry proved to be a useful tool for enumeration of total bacterial counts and in the assessment of within-culture cell viability and cell death. Of the cryoprotectants evaluated, 5% (v/v) DMSO showed the most significant positive effect on survival and reduced the negative effects of low temperature storage on M. bovis BCG Danish viability. In conclusion, we have shown a reproducible, more standardised approach for the production, evaluation, and storage of high titre, viable, BCG vaccine.

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“…BCG vaccines in rubber-stoppered vials previously showed a lower stability than those conserved in ampoules (82,121), although this seems not to be the case with currently supplied vaccines that use rubber stoppers.…”

Section: Packing Bcg Vaccinesmentioning

confidence: 93%