Study of the stability of proteoliposomes as vehicles for vaccines against Neisseria meningitidis based on recombinant porin complexes

Although effective against epidemic serogroup B Neisseria meningitidis strains, vaccines based on outer membrane vesicles continue to present important limitations, and great efforts are currently being focused in the development of a variety of new vaccine candidates and in the reformulation of currently existing ones. In this work, three N. meningitidis proteins, the PorA and PorB porins and the RmpM protein, were cloned, purified and incorporated into liposomes to build defined systems. The ability of proteoliposomes to allow the refolding porin complexes, and their stability during storage at 4°C and after lyophilization in presence of two cryoprotection agents, glucose and trehalose, were evaluated. This approach allowed to mimic the porin complexes present in natural OMVs, reducing the content of hypervariable protein PorA. During storage at 4°C, our systems showed some changes in the morphology and aggregation after three months, while after lyophilization the systems maintained their properties during the whole nine months of storage checked, with glucose allowing the best preservation of the antigenic properties of the proteins in the proteoliposomes.