(10). spike (S) proteins. The S protein is posttranslationally cleaved into the N-terminal S1 and C-terminal S2 glycoproteins. The S1 glycoprotein induces virus-neutralizing and hemagglutination-inhibiting antibodies (5, 15). Therefore, the S1 glycoprotein may be useful as a vaccine component. The commercial live and inactivated vaccines that have been used to control IBV-associated disease in chickens (4) have some disadvantages. Inactivated vaccines are safe but are costly and less effective than live attenuated vaccines, while attenuated vaccines may be associated with the emergence of variant strains of the virus (11, 21, 22). Thus, there is a need for Ac-Lys-AMC vaccines with higher efficacy and fewer side effects. The expression of recombinant proteins in transgenic plants was first reported in 1995 by Haq et al. (10). Since then, several viral and bacterial antigens have been efficiently expressed in transgenic plants (1, 2, 8, 9, 12, 13, 14, 18, 19). In this paper, we report the expression of the S1 glycoprotein of IBV in transgenic plants and demonstrate its immunogenicity in mice. We also show that chickens immunized with the transgenic plants are protected against a challenge with virulent IBV. A pair of specific primers, based on the cDNA sequence of the S protein-encoding gene of IBV strain ZJ971, was designed to amplify the S1 gene of IBV (22). Strains ZJ971, H52, and M41 have the same serotype and have 97.1 Ac-Lys-AMC to 99.7% S1 gene identity. The upstream primer 5-GCTCTAGAATGTTGGTAACACCTCTT-3 contained the EHA105 (Clontech) from by triparental mating as described by Ditta et al. (7). EHA105 was used to transfer the constructs into Ac-Lys-AMC potato plants (cv. Dongnong303) as described previously (3). Open in a separate window FIG. 1. Schematic structure of binary plasmid pBI121, which was used for B. W. Calnek, H. J. Barnes, C. W. Beard, L. R. McDougald, and Y. M. Saif (ed.), Diseases of poultry, 10th ed. Iowa State University Press, Ames. 5. Cavanagh, D., P. Ac-Lys-AMC J. Davis, J. H. Darbyshire, and R. W. Peters. 1986. Coronavirus IBV: virus retaining spike glycopolypeptide S2 but not S1 is unable to induce virus-neutralizing or haemagglutination inhibiting antibody, or induce chicken tracheal protection. J. Gen. Virol. 67:435-1442. [PubMed] [Google Scholar] 6. Cook, J. K. A., J. H. Darbyshire, and R. W. Peter. 1976. The use of chicken trachea organ culture for the isolation and assay of infectious bronchitis virus. Arch. Virol. 50:109-118. [PubMed] [Google Scholar] 7. Ditta, D., S. Stanfield, D. Corbin, and D. R. Helinskim. 1980. Broad host range DNA cloning system for gram-negative bacteria: construction of a gene bank of in transgenic plants. Virology 249:352-358. [PMC free article] [PubMed] [Google Scholar] 10. Haq, T. A., H. S. Mason, J. D. Clements, and C. J. Arntzen. 1995. Oral immunization with a recombinant bacterial antigen produced in transgenic plants. Science 268:714-716. [PubMed] [Google Scholar] 11. Jia, W., K. Karaca, C. R. Parrish, and S. A. Naqi. 1995. A novel variant of avian infectious bronchitis virus resulting from recombination among three different strains. Arch. Virol. 140:259-271. [PMC free article] [PubMed] [Google Scholar] 12. Mason, H. S., T. A. Haq, J. D. Clements, and C. J. Arntzen. 1998. Edible vaccine protects mice against heat-labile enterotoxin (LT): potatoes expressing a synthetic LT-B gene. Vaccine 16:1336-1343. [PubMed] [Google Scholar] 13. Mason, H. ST16 S., J. M. Ball, J. J. Shi, X. Jiang, M. K. Estes, and C. J. Arentzen. 1996. Expression of Norwalk virus capsid protein in transgenic tobacco and potato and its oral immunogenicity in.