Plant-made subunit vaccine against pneumonic and bubonic plague is orally immunogenic in mice

Yersinia pestis, the causative agent of plague, is an extremely virulent bacterium but there are no approved vaccines for protection against it. Our goal was to produce a vaccine that would address: ease of delivery, mucosal efficacy, safety, rapid scalability, and cost. We developed a novel production and delivery system for a plague vaccine of a Y. pestis F1–V antigen fusion protein expressed in tomato. Immunogenicity of the F1–V transgenic tomatoes was confirmed in mice that were primed subcutaneously with bacterially-produced F1–V and boosted orally with transgenic tomato fruit. Expression of the plague antigens in fruit allowed producing an oral vaccine candidate without protein purification and with minimal processing technology.