Veterinary vaccines from transgenic plants: highlights of two decades of research and a promising example.

In the last two decades the development of efficient plant-based expression strategies and new concepts for the purification of recombinant proteins prompted the application of plant-derived vaccines for veterinary purposes. The expression of recombinant proteins in plants possesses advantages over conventional eukaryotic expression systems and therefore represents a versatile tool for the production of "edible" and "seasonal" vaccines. This review aims to provide an overview about the expression of vaccines using transgenic plants for veterinary medicine with the focus on increasing the amount of the recombinant proteins as well as concepts for their efficient purification. ELPylation of recombinant proteins is one strategy for on one side boosting the amount of the recombinant protein and on the other side simplifying its purification. This up-and-coming tool was applied for the development of effective production and purification strategies for antigens against Avian Flu, a very important animal disease with a strong economic impact. Future perspectives of plant-based veterinary vaccines in the context of purification and economy are also discussed within this article.