Alginate microparticles for vaccine delivery

Many pathogens initially establish infection on the mucosal surfaces lining the respiratory and gastrointestinal tracts in both man and animals. Although immunization against infectious pathogens is frequently effective, efficacy could be enhanced if directed specifically to the mucosal surfaces. Oral immunization in particular would be advantageous, since large numbers of individuals could be quickly and easily immunized, possibly through the feed or drinking water. Efforts at oral immunization are hampered by dilution and destruction of antigens within the harsh environment of the gastrointestinal tract. Encapsulation of antigen in alginate microparticles was examined as a means to orally immunize rabbits against the important bacterial pathogen, Pasteurella multocida. Initial studies in mice showed that the bacterial load of microparticles could be reduced by a factor of 10³ by boiling, but that this process diminished the immunogenicity of a potassium thiocyanate extract of P. multocida (PTE) incorporated into the microparticles. Studies in rabbits showed that incorporation of PTE into alginate microparticles allowed effective immunization through the drinking water. Alginate microparticles can be used for immunization against infectious disease; however, alternative methods for sterilization will need to be pursued.