Epitope-display system

Tab. 9.1 Vaccine antigens expressed in plant virus epitope display systems. 

In the second research strategy, plant viruses have been utilized as pliable genetic platforms for protein expression. Three formats have been developed, and the one that has undergone the most extensive evaluation is the display of epitopes on the surface of the virus as fusions with the viral coat protein. This epitope-display system... 

Two types of expression systems based on plant RNA viruses have been developed for production of immunogenic peptides and proteins in plants epitope presentation systems (short antigenic peptides fused to the CP that are displayed on the surface of assembled viral particles) and polypeptide expression systems (these systems express the whole unfused recombinant protein that accumulates within the plant). 

Nguyen TN, Hansson M, Stahl S, Bachi T, Robert A, Domzig W, Binz H, Uhlen M, Cell-surface display of heterologous epitopes on Staphylococcus xvlosus as a potential delivery system for oral vaccination, Gene, 128 89-94, 1993. 

The immune system does mount a vigorous response in these early days. Macrophages ingest the viral particles and degrade them, and then display small portions of the virus (small peptides called epitopes) on their surface, and this attracts the attentions of helper T-cells, which in turn activate killer T-cells and B-lymphocytes. The killer T-cells attack cells displaying the viral epitopes, and the B-cells produce dedicated antibodies that also seek out and destroy such cells. Not surprisingly, in the early days after infection, around 30% of patients exhibit typical symptoms of their immune response to viral... 

Phage display antibody libraries are relatively new and have been used in a few P450 applications to date (D.S. Keeney personal communication). These have a number of advantages, including jjotential selectivity due to the large number of potential antibodies in libraries, the ability to avoid animal protocols, the immediate availability of libraries (as opposed to waiting on animals to develop antibodies), the consistency of reproduction of the proteins propagated in bacterial systems, and the ability to include a second epitope tag for recovery, etc. 

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