Abstract:

The ability of an oil-based carrier vehicle to act as an antigen delivery system via the oral and/or parenteral routes was investigated. The formulation consists of hydrophilic macromolecules (antigens) solubilised in oil phase, in the absence of water, by virtue of being wrapped in a sheath of phospholipid amphiphile. Results obtained demonstrate that the level of mucosal IgA antibodies detected in the stools of mice immunised orally with cholera toxin B fragment (CTB) or E. coli heat-labile toxin (LT) in oil is much higher than the level of IgA produced by mice immunised with CTB or LT alone. In addition, mice immunised orally with Y. pestis antigens (F1 and V) and CTB as immunostimulant in oil produce a significantly increased (p<0.02) systemic IgG response against both antigens (F1 and V) than mice orally immunised with F1, V and CTB without oil. Six out of ten mice immunised with F1 and V antigens in oil survived an aerosol challenge of 100 LD50 doses of virulent Y. pestis. Furthermore, animals immunised sub-cutaneously with the HIV antigen (HGP-30) in oil induced much stronger humoral and cellular responses against the antigen than mice immunised with the antigen alone. Taken together, these findings indicate that oil can be used successfully as an antigen delivery system in vaccine formulations without the necessity of an aqueous phase or an emulsification process. This greatly enhances the stability and ease of production of a formulation manufactured for commercial use.