Epstein-Barr virus (EBV) infects nearly 90% of adults worldwide and is the pathogenic source of a broad spectrum of malignancies originating from lymphoid and epithelial cells. Currently, no vaccine has been developed to immunologically inactivate this virus. In infected patients, anti-EBV viral capsid antigen (VCA) immunoglobins represent some of the useful diagnostic markers for carcinoma development. To demonstrate that the EBV VCA antigen can be produced in plants, the plastid genome of tobacco (Nicotiana tabacum cv. SR1) was transformed with a VCA-expressing cassette. The EBV VCA mRNA was actively transcribed in the transplastomic plants and antigen production was detected. This study indicates that plastid transformation could be a promising strategy in EBV VCA antigen production. (c) 2006 Wiley Periodicals, Inc.