Optimization of the entrapment of bacterial cell envelope extracts into microparticles for vaccine delivery.

The encapsulation of a Brucella ovis extract (HS) in microparticles has been proved effective against experimental infections in mice. This work describes different strategies to increase the HS loading and prepare large batches as necessary to test this vaccine in ovine. The mixture of HS with beta-cyclodextrin was optimized in order to increase the HS loading in microparticles. On the other hand, TROMS ('Total Recirculation One-Machine System') led microparticles with a more homogeneous size than the laboratory or standard procedure. Moreover, the initial burst release of HS from the standard microparticles was higher than for the TROMS ones. In fact, standard microparticles displayed a higher amount of adsorbed HS. On the contrary, both preparative methods were found effective to preserve the integrity and anti-genicity of the loaded HS. In summary, beta-CD can be used to increase the loading of large hydrophobic materials and TROMS is a valid large production of antigen-loaded microparticles.