ABSTRACT
Transgenic plants represent a safe, effective, and inexpensive way to produce vaccines. The immunogenicity of VP2 protein of an infectious bursal disease (IBD) virus variant E isolate expressed in transgenic Arabidopsis thaliana was compared with a commercial vaccine in specific-pathogen-free broiler chickens. The VP2 coding sequence was isolated and integrated into A. thaliana genome by Agrobacterium tumefaciens-mediated transformation. Soluble VP2 expressed in transgenic plants was used to immunize chickens. Chickens receiving oral immunization with plant-derived VP2 at 1 and 3 wk of age had an antibody response using enzyme-linked immunosorbent assay and 80% protection against challenge infection at 4 wk. Chickens primed with a commercial vaccine at 1 wk followed by an oral booster with VP2 expressed in plants at 3 wk of age showed 90% protection. Chickens immunized with a commercial vaccine at 1 and 3 wk showed 78% protection. Results supported the efficacy of plant-produced VP2 as a vaccine against IBD.
Subject(s)
Antibodies, Viral/immunology , Arabidopsis/virology , Birnaviridae Infections/veterinary , Chickens/virology , Infectious bursal disease virus/immunology , Poultry Diseases/prevention & control , Viral Vaccines/immunology , Age Factors , Agrobacterium tumefaciens , Animals , Birnaviridae Infections/prevention & control , Chickens/immunology , Enzyme-Linked Immunosorbent Assay , Plants, Genetically Modified , Poultry Diseases/virology , Transformation, Genetic , Viral Structural Proteins/genetics , Viral Structural Proteins/metabolismABSTRACT
VP2 protein is the major host-protective immunogen of infectious bursal disease virus (IBDV) of chickens. Transgenic lines of Arabidopsis thaliana expressing recombinant VP2 were developed. The VP2 gene of an IBDV antigenic variant E strain was isolated, amplified by RT-PCR and introduced into a plant expression vector, pE1857, having a strong promoter for plant expression. A resulting construct with a Bar gene cassette for bialaphos selection in plant (rpE-VP2) was introduced into Agrobacterium tumefaciens by electroporation. Agrobacterium containing the rpE-VP2 construct was used to transform Ar. thaliana and transgenic plants were selected using bialaphos. The presence of VP2 transgene in plants was confirmed by PCR and Southern blot analysis and its expression was confirmed by RT-PCR. Western blot analysis and antigen-capture ELISA assay using monoclonal anti-VP2 were used to determine the expression of VP2 protein in transgenic plants. The level of VP2 protein in the leaf extracts of selected transgenic plants varied from 0.5% to 4.8% of the total soluble protein. Recombinant VP2 protein produced in plants induced antibody response against IBDV in orally-fed chickens.
