UC Davis

The production of vaccines in plant cells, termed plant-made pharmaceuticals or molecular farming, is a promising technology for scalable production. Compared to mammalian cell lines, like Chinese Hamster Ovary (CHO) or bacterial cells, plants can be grown with less cost on a large scale to make vaccines antigens and therapeutics affordable and accessible worldwide. An innovative application of this alternative system is the production of vaccines in edible tissues that can be consumed orally to deliver protein antigen without any further processing. In this project, we report stable expression of amino acid sequences corresponding to the TM-1 gene of Mycoplasma gallisepticum as a candidate vaccine antigen against Chronic Respiratory Disease (CRD) in chickens using wheat seed's tissues as a production host. Molecular and immunoblotting analysis confirmed the ubiquitous expression of a recombinant 41.8-kDa protein with an expression level of 1.03 mg/g dry weight in the endosperm tissues. When orally delivered, the plant-made vaccine was effective in terms of developing antibody response in animal model i.e., chicken without any detectable weight loss. Two doses of orally delivered plant-made TM-1 vaccine candidate elicited the immune response and protective effect against MG virus challenge at the level comparable to commercially available inactivated vaccine against CRD. Our study demonstrates that plant-made vaccines are not only safe but also scalable and cost-effective with prolonged stability at room temperature.