Abstract
Ensuring the stability of vaccines is crucial to successfully performing global immunization programs. Outer Membrane Vesicles (OMV) are receiving great attention as vaccine platforms. OMV are complex molecules and few data have been collected so far on their stability. OMV produced by bacteria, genetically modified to increase their spontaneous release, simplifying their production, are also known as Generalized Modules for Membrane Antigens (GMMA). We have performed accelerated stability studies on GMMA from different pathogens and verified the ability of physico-chemical and immunological methods to detect possible changes. High-temperature conditions (100 °C for 40 min) did not affect GMMA stability and immunogenicity in mice, in contrast to the effect of milder temperatures for a longer period of time (37 °C or 50 °C for 4 weeks). We identified critical quality attributes to monitor during stability assessment that could impact vaccine efficacy. In particular, specific recognition of antigens by monoclonal antibodies through competitive ELISA assays may replace in vivo tests for the potency assessment of GMMA-based vaccines.
Highlights
Outer Membrane Vesicles (OMV) are spherical bi-layered membrane structures with a diameter in the range of 20–250 nm, naturally released by Gram-negative bacteria during their growth [1]
Typhimurium and S. flexneri 2a Generalized Modules for Membrane Antigens (GMMA) incubated at 50 ◦ C, we found that specific anti-OAg monoclonal antibodies (mAb) did no longer bind to the OAg displayed on GMMA after thermal stress (Table 2), reflecting changes observed for corresponding OAg in terms of O-acetylation level
We have demonstrated that we can monitor changes occurring in GMMA with a comprehensive panel of analytical methods
Summary
Outer Membrane Vesicles (OMV) are spherical bi-layered membrane structures with a diameter in the range of 20–250 nm, naturally released by Gram-negative bacteria during their growth [1]. They are primarily made of bacterial outer membrane constituents, containing key antigenic components to elicit an immune response [2]. Bacteria can be genetically manipulated in order to enhance OMV release [8], resulting in hyperblebbing microorganisms whose blebs have been called GMMA (Generalized Modules for Membrane Antigens). GMMA production process is simple and highly cost-effective [8,11]
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