Plant Expression of Trans-Encapsidated Chimeric Viral Vaccines with Animal RNA Replicons: An Update

In this protocol, we outline how to produce a chimeric viral vaccine in a biosafety level 1 (BSL1) environment. An animal viral vector RNA encapsidated with tobacco mosaic virus (TMV) coat protein can be fully assembled in planta. Agrobacterium cultures containing each component are inoculated together into tobacco leaves and the self-assembled hybrid chimeric viral vaccine is harvested 4 days later and purified with a simple PEG precipitation. The viral RNA delivery vector is derived from the BSL1 insect virus, Flock House virus (FHV), and replicates in human and animal cells but does not spread systemically. A polyethylene glycol purification protocol is also provided to collect and purify these vaccines for immunological tests. In this update, we also provide a protocol for in trans co-inoculation of a modified FHV protein A, which significantly increased the yield of in planta chimeric viral vaccine.