Plant Virus-Mediated Expression in Molecular Farming

Abstract

Plant viruses have contrasting abilities. On one hand, they can induce gene silencing, termed as virus-induced gene silencing. On the other hand, they have evolved mechanisms that suppress gene silencing and allow the accumulation of very high levels of viral proteins in infected plants. The latter is the driving force for the manipulation of plant viruses for molecular farming in plants. In comparison to the transgenic approach which is often associated with low levels of expression and the requirement of a time-consuming and labour-intensive genetic transformation process, the plant virus-mediated expression approach has several advantages such as easy manipulation, high yield and fast manufacturing. This approach uses plant virus-based expression vectors as a vehicle to produce therapeutic proteins such as antibodies, enzymes, vaccines, and other recombinant proteins of interest in plants. Over the last two decades, a number of plant viruses have been developed and optimized for expression of a variety of pharmaceutical proteins. Some of these recombinant proteins are currently under pre-clinical or clinical trials. In this chapter, I will summarize recent progress, current challenges and future prospects of plant virus-mediated expression in molecular farming.