Toward the Development of a Plant-Based Vaccine Against Reovirus

Transgenic lines of Arabidopsis thaliana producing recombinant sigma C protein were developed. The S1 gene encoding sigma C protein of an avian reovirus (ARV) was amplified by reverse-transcription PCR (RT-PCR). The amplified product was cloned into a plant-expression vector, pE1857, with a strong promoter for expression. The resulting construct with the BAR gene cassette for bialaphos selection was designated rpE-sigma C and was introduced into Agrobacterium tumefaciens by electroporation. Agrobacterium containing the rpE-sigma C constructs that transform A. thaliana and transgenic plants were selected using bialaphos selection. The presence of S1 transcript in plants and their relative level of expression were determined by real time RT-PCR. Western blot analysis further confirmed the presence of sigma C protein in the plants. Transgenic lines with high levels of sigma C protein were selected for immunization experiments using specific-pathogen free chickens. Recombinant sigma C protein produced in plants induced a variety of immunoglobulin G (IgG) antibody responses in chickens. Recombinant protein administered either subcutaneously or orally in birds showed significant protection against challenge. Results suggested that the recombinant sigma C protein produced in plants has the potential for large-scale vaccination against ARV in commercial poultry.