A plant-derived edible vaccine against hepatitis B virus

The infectious hepatitis B virus represents 42 nm spherical double-shelled particles. However, analysis of blood from hepatitis B virus carriers revea led the presence of smaller 22 nm particles consisting of a viral envelope surface protein. These particles are highly immunogenic and have been used in the design of hepatitis B virus vaccine produced in yeast. Upon expressi on in yeast, these proteins form virus-like particles that are used for par enteral immunization. Therefore, the DNA fragment encoding hepatitis B viru s surface antigen was introduced into Agrobacterium tumerifacience LBA4404 and used to obtain transgenic lupin (Lupinus luteus L.) and lettuce (Lactuc a sativa L.) cv. Burpee Bibb expressing envelope surface protein. Mice that were fed the transgenic lupin tissue developed significant levels of hepat itis B virus-specific antibodies. Human volunteers, fed with transgenic let tuce plants expressing hepatitis B virus surface antigen, developed specifi c serum-IgG response to plant produced protein.