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Stability of mono- and trivalent meningococcal outer membrane vesicle vaccines
Carmen Arigita1, Wim Jiskoot, Janny Westdijk
1Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
Abstract:
The stability during storage of outer membrane vesicles (OMVs) of Neisseria meningitidis group B was studied. Three types of OMVs were compared for their stability, containing either one (monovalent) or three different PorA subtypes (trivalent), the latter with and without class 4 outer membrane protein (OMO, RmpM). Aqueous formulations were stored freeze-dried (4 degrees C), frozen (-70 degrees C) and in liquid form at 4, 37 and 56 degrees C. Physico-chemical properties and immunogenicity of the OMVs as well as PorA conformation and antigenicity (P1.7-2,4, the subtype present in all formulations) were monitored during 1 year. At -70 or 4 degrees C, the structure and immunogenicity of OMVs was preserved. Storage of OMVs at high temperatures (37 or 56 degrees C) induced destruction of the OMV structure and denaturation of PorA, followed by chemical degradation. Immunogenicity decreased or was lost completely. Changes observed in the fluorescence spectra of degraded OMVs were also seen in tryptophan (Trp) and tyrosine (Tyr) derivatives incubated at 56 degrees C, indicating the occurrence of chemical degradation of tryptophan and tyrosine residues in PorA. Trivalent OMVs were slightly more stable at 37 degrees C than monovalent OMVs as assessed by in vitro methods, but these differences did not result in differences in the immunogenicity. The stability of trivalent OMVs was not affected by the presence of RmpM. Both trivalent and monovalent OMVs could be freeze-dried with preservation of their immunogenicity. In conclusion, OMVs are sensitive to elevated temperatures, but are stable in the frozen or freeze-dried state or when stored at 4 degrees C in the liquid state.
Insights
Outer membrane vesicles (OMVs) from Neisseria meningitidis group B are stable when frozen or freeze-dried. High temperatures degrade OMVs and PorA protein, reducing immunogenicity.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Outer membrane vesicles (OMVs) are crucial vaccine candidates.
- Neisseria meningitidis group B OMVs containing PorA subtypes are under investigation.
- Understanding OMV stability is vital for vaccine development and storage.
Purpose of the Study:
- To evaluate the storage stability of Neisseria meningitidis group B OMVs.
- To compare the stability of monovalent and trivalent PorA OMVs.
- To assess the impact of temperature and formulation on OMV integrity and immunogenicity.
Main Methods:
- Storage of OMVs in aqueous formulations under various conditions: freeze-dried (4°C), frozen (-70°C), and liquid (4°C, 37°C, 56°C).
- Monitoring of physico-chemical properties, PorA conformation and antigenicity (P1.7-2,4), and immunogenicity over one year.
- Analysis of OMV structure, PorA integrity, and potential chemical degradation using fluorescence spectroscopy.
Main Results:
- OMVs preserved structure and immunogenicity when stored at -70°C or 4°C.
- High temperatures (37°C, 56°C) caused OMV structural destruction, PorA denaturation, and loss of immunogenicity.
- Chemical degradation of tryptophan and tyrosine residues in PorA was indicated at elevated temperatures.
- Trivalent OMVs showed slightly better in vitro stability at 37°C, but this did not affect immunogenicity.
- Freeze-drying preserved the immunogenicity of both monovalent and trivalent OMVs.
- RmpM did not affect the stability of trivalent OMVs.
Conclusions:
- Neisseria meningitidis group B OMVs are sensitive to elevated temperatures.
- Stable storage of OMVs is achievable when frozen, freeze-dried, or kept liquid at 4°C.
- Freeze-drying is a viable method for preserving OMV immunogenicity.
- Optimal storage conditions are critical for maintaining the efficacy of OMV-based vaccines.
