A new oral vaccine candidate based on the microencapsulation by spray-drying of inactivated Vibrio cholerae

The aim of this work was to evaluate the microencapsulation by spray-drying of inactivated Vibrio cholerae, using methacrylic copolymers Eudragit® L30D-55 and FS30D. The microparticles obtained presented a particle size around 3.0 μm. The preparation temperature affected the morphology and the antigenicity of microparticles, but it did not affect the V. cholerae content. In vitro release studies showed that in acid medium less than 5% of bacteria was released, and in neutral medium, Eudragit® L30D-55 microparticles released 86% after 24 h, whereas FS30D released less than 30%. Rats inoculated with microparticles exhibited vibriocidal antibody titres. Microencapsulation by spray-drying of inactivated V. cholerae could be proposed as a method to obtain an oral vaccine which provides controlled release of the bacteria.