Overcoming antigenic diversity and improving vaccines using DNA shuffling and screening technologies.

Viral, bacterial and parasitic pathogens have evolved multiple strategies to evade the immune response, facilitate transmission and establish chronic infections. One of the underlying strategies that pathogens have evolved is antigenic variation of immune response targets that reduce the affinity of antigen binding to antibodies and major histocompatability complex class I and II receptors. Vaccine candidates generally target a limited number of these antigen variants or combine antigens from several variants to include in multivalent vaccine formulations. DNA shuffling and screening technologies, also known as MolecularBreeding (Maxygen, Inc.) directed molecular evolution, have been successfully used to identify and develop novel and chimaeric vaccine candidates capable of inducing immune responses that recognise and control multiple antigenic variants. DNA shuffling and screening strategies also select vaccine candidates with improved immunogenicity, increased expression as recombinant polypeptides and improved growth of whole viruses in cell culture. As DNA shuffling and screening strategies can be applied to many pathogens, there remain numerous applications of DNA shuffling to solve challenging problems in vaccine process development and manufacture.