Effect of Tobacco Mosaic Virus (TMV) Infection on Expression and Purification of Therapeutic Vaccine Proteins in Transgenic Plants

Plant molecular biofarming has been increasingly studied in recent decades. Many kinds of recombinant immunotherapeutic proteins have been produced in transgenic tobacco plants. However, tobacco mosaic virus (TMV) can damage tobacco plants and cause pathogenic symptoms, which affects plant biomass production. Cigarette sap solution has been used to infect TMV during tobacco cultivation. In this study, we obtained TMV-infected transgenic plants expressing a prostatespecific antigen (PSA) fused to an IgG Fc with KDEL ER retention motif (PSA-IgG FcK). The typical TMV-associated symptoms appeared and increased on plant leaves 5 days after infection. mRNA expression levels and the presence of TMV were confirmed by RT-PCR and transmission electron microscopy analyses. The expression level and purity of the target protein were not significantly different between noninfected and infected transgenic plants. TMV was not found in the purified protein samples from infected plants. Our study showed that TMV pathogen-infected plant biomass can be harvested and processed to obtain therapeutic vaccine proteins.