Research Article Leaf-Encapsulated Vaccines: Agroinfiltration and Transient Expression of the Antigen Staphylococcal Endotoxin B in Radish Leaves Pei-Feng Liu, 1 Yanhan Wang, 1 Robert G. Ulrich, 2 Christopher W. Simmons, 3 Jean S. VanderGheynst, 3 Richard L. Gallo, 1 and Chun-Ming Huang 1,4 1 Department of Dermatology, University of California, San Diego, CA 92161, USA 2 Department of Immunology, Army Medical Research Institute of Infectious Diseases, Frederick, MD 21703, USA 3 Department of Biological & Agricultural Engineering, University of California, Davis, CA 95616, USA 4 Department of Dermatology and Moores Cancer Center, University of California, San Diego, CA 92161, USA Correspondence should be addressed to Chun-Ming Huang; chunming@ucsd.edu Received 26 February 2017; Revised 24 September 2017; Accepted 10 October 2017; Published 7 February 2018 Academic Editor: Stuart Berzins Copyright © 2018 Pei-Feng Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Transgene introgression is a major concern associated with transgenic plant-based vaccines. Agroinfiltration can be used to selectively transform nonreproductive organs and avoid introgression. Here, we introduce a new vaccine modality in which Staphylococcal enterotoxin B (SEB) genes are agroinfiltrated into radishes (Raphanw sativus L.), resulting in transient expression and accumulation of SEB in planta. This approach can simultaneously express multiple antigens in a single leaf. Furthermore, the potential of high-throughput vaccine production was demonstrated by simultaneously agroinfiltrating multiple radish leaves using a multichannel pipette. The expression of SEB was detectable in two leaf cell types (epidermal and guard cells) in agroinfiltrated leaves. ICR mice intranasally immunized with homogenized leaves agroinfiltrated with SEB elicited detectable antibody to SEB and displayed protection against SEB-induced interferon-gamma (IFN-γ) production. The concept of encapsulating antigens in leaves rather than purifying them for immunization may facilitate rapid vaccine production during an epidemic disease. 1. Introduction Transgenic plants have emerged as a promising technology to generate recombinant biopharmaceutical proteins and vaccines [1, 2]. Plants produce full-length mammalian pro- teins that appear to be processed correspondingly to their native counterpart with appropriate folding, assembly, and posttranslational modifications [3]. Although stably trans- formed transgenic plants have been widely created to deliver edible vaccines [4, 5] and have proven success in clinical trials [6, 7], the fact that transgenes are permanently incorporated into the genomes of transgenic plants raises many concerns, such as the environmental release of genetically modified plants and the possibility of transgene introgression into nonmodified counterparts [8]. In addition, immunization with edible vaccines derived from transgenic plants may carry a risk of inducing oral tolerance due to immunization with multidoses within a long period of time. Transient expression of recombinant proteins in leaf tissue avoids transgene introgression and provides a fast platform for pro- tein production without an effort-exhaustive process to gen- erate stably transformed transgenic plants [9]. Currently, there are at least four approaches to transform- ing and inducing transient expression in plants: (1) delivery of “naked” DNA by particle bombardment [10], (2) infection with modified viral vectors [6, 10, 11], (3) agroinfiltration of plant tissues with Agrobacteria [10, 12], and (4) polyethylene glycol- (PEG-) mediated gene transfer and electroporation of protoplasts [13]. Agroinfiltration accommodates transform- ing plants with large genes encoding complex proteins, such Hindawi Journal of Immunology Research Volume 2018, Article ID 3710961, 9 pages https://doi.org/10.1155/2018/3710961