Successful oral prime-immunization with VP60 from rabbit haemorrhagic disease virus produced in transgenic plants using different fusion strategies.

Expression levels of vaccine antigens in transgenic plants have important consequences in their use as edible vaccines. The major structural protein VP60 from the rabbit haemorrhagic disease virus (RHDV) has been produced in transgenic plants using different strategies to compare its accumulation in plant tissues. The highest expressing plants were those presenting stable, complex, high-density structures formed by VP60, suggesting the importance of multisubunit structures for the stability of this protein in plant cells. Mice fed with leaves of transgenic plants expressing VP60 were primed to a subimmunogenic baculovirus-derived vaccine single dose. This indicates that plants expressing VP60 antigen may be a new means for oral RHDV immunization.