Starch granules as a vehicle for the oral administration of immobilized antigens

Microparticles of diverse compositions are often used as carriers for interesting antigens. In this work, we propose the use of natural microparticulated starch as a vehicle for antigens. The proposed system is composed of raw starch microparticles and a starch-binding domain that when fused to another protein, allows for a stable protein immobilization onto the granule surface. To demonstrate the use of starch as an antigen carrier, a fusion combining fragment C of the tetanus toxin with the starch-binding domain was adsorbed to starch and administered orally to mice in two different doses and, importantly, without the use of any adjuvant. The results showed that the system allows the induction of specific antibodies; moreover mice given this immobilized protein presented a delay in the onset of tetanus symptoms compared to mice administered the non-immobilized protein. The study outlines the viability of this immobilization system as an antigen and protein carrier.