Genetic subunit vaccines : a novel approach for genetic immunization

Induction of epitope-specific cytotoxic T lymphocyte (CTL) responses can improve the outcome of disease in a variety of model systems. However, natural immunity or that arising by immunization with whole proteins or organisms with multiple potential epitopes, may not always result in the desired effect. For example, antigenic variation of CTL epitopes can result in immune escape in HIV disease (1,2), and malaria (3). This could potentially be avoided if it were possible to direct the immunity to selected regions of proteins that are highly conserved and required for function. The immunization with specific CTL epitopes rather than whole proteins also avoids induction of unwanted responses such as enhancing antibodies in HIV, which may actually promote infection (4).