The invention is directed to the use of (i) a first antigen corresponding to a target antigen of interest, together with (ii) a second antigen, corresponding to a modified form of the target antigen, whose rate of intracellular proteolytic degradation is increased, enhanced or otherwise elevated relative to the first antigen, in compositions and methods for inducing both humoral and cellular immunity in an individual. The ability to provide compositions, which are capable of inducing both host-protective antibody and cell-mediated immune responses, facilitates the generation of immunogenic compositions capable of combating, inter alia, conditions that have long latency periods and, therefore, benefit from the dual approach of prophylaxis and therapy in one delivery.