Lipospheres for Vaccine Delivery

This chapter describes the physicochemical properties and immunogenic activity of different liposphere–vaccine formulations containing a recombinant malaria antigen, liposphere, derived from the circumsporozoite protein of Plasmodium falciparum as the model antigen. Lipospheres, which represent a new type of fat-based encapsulation technology developed for parenteral drug delivery, have also been used successfully as carriers of vaccines and adjuvants. The feasibility of developing a human malaria sporozoite vaccine was demonstrated in a clinical trial by using irradiated sporozoites as antigens. Protection against sporozoite infection apparently can be achieved by inducing a high titer of antisporozoite antibodies. Manufacture of lipospheres was accomplished by gently melting the neutral fat, in the presence of phospholipid, and dispersing the mixture in an aqueous solution of the antigen by vigorous shaking, which results on cooling, in the formation of a phospholipid-stabilized, solid hydrophobic fat core containing the antigen.