Tobacco plants have been genetically engineered to express thesurface antigen for the hepatitis B virus (HBsAg) in theirleaves, thus opening the way for using transgenic plants aslow-cost, potentially edible vaccine production systems.

Texas A&M University researcher Hugh Mason and associatesreported in the current issue of the Proceedings of the NationalAcademy of Sciences that not only were the transgenic plantsable to transcribe and translate the foreign gene, but that therecombinant HBsAg is antigenically and physically similar tothe HBsAg particles derived from human serum and fromrecombinant yeast, which are now used as vaccines.

Mason and his colleagues Dominic Man-Kit Lam and CharlesArntzen found that the maximal levels of HBsAg in theirtransgenic plants equaled only about 0.01 percent of the totalsoluble leaf protein. They admit that this is "an inadequatelevel for the efficient use of plants as production systems forrHBsAg for vaccine use," but that is their ultimate goal.

Current hepatitis B vaccines are too expensive to administer at-large in developing nations, which are hard-hit by hepatitis Binfection; there are more than 100 million virus carriers inChina, for instance. Harnessing plants to make the vaccinesshould provide cheaper versions -- perhaps even ones that canbe ingested via edible plant tissues.

-- Jennifer Van Brunt Senior Editor

(c) 1997 American Health Consultants. All rights reserved.