Split core carrier for a foreign molecule against which an immune response is to be elicited comprises the N and C domains of a hepatitis B virus core protein as separate polypeptides, the foreign molecule being fused to the C-terminus of the N domain or the N-terminus of the C domain. The core protein is capable of binding capsid-like particles. An independent claim is also included for producing a carrier as above by expressing the foreign molecule and the N or C domain as a fusion protein or inserting a protease recognition sequence between the foreign molecule and the N or C domain and cleaving the product with the protease, and forming capsid-like particles. ACTIVITY : Antibacterial; Protozoacide; Virucide; Cytostatic. MECHANISM OF ACTION : Vaccine.