Plantibody

A plantibody (derived from Plant and antibody) is a special type of antibody created from genetically altered crops. The term plantibody as well as the concept is trademarked by the company Biolex. The term was first cited in 1989 referring to an antibody produced by introducing antibody genes (from mice or humans) into a plant through a process called genetic transformation. Although plants do not have an immune system of their own, and do not normally make antibodies, plantibodies have been shown to function in the same way as normal antibodies. A number of companies in addition to Biolex, including Planet Biotechnology in California, and Medicago in Canada are pursuing the commercial development of plantibodies as therapies for everything from cancer to the common cold. A number of plant species are being experimented with in the production and cultivation of plantibodies.

Humanized plantibodies maybe used to avoid severe allergic reactions. Also, the difference between plantibodies and edible vaccines is that plantibodies are pre-made antibodies that are produced in the transgenic plant; whereas edible vaccines promote the production of specific antibodies by the human immune system once the vaccine is administered to the patient. Plantibodies are advantageous for people who are immunosuppressed and are unable to produce antibodies even after they are vaccinated. The problem, however is that these immunodeficient patients are dependent on re-administration of the plantibodies because of their inability to produce their own antibodies for the same pathogen.

Foreign gene expression in plants can be accomplished either by stable integration of foreign DNA or by transient expression using modified plant viruses. Stable genomic integration is accomplished by introducing foreign DNA in the plant either by Agrobacterium T-DNA vectors or by direct means. The integration method has the advantage of permitting large scale cloning, maintenance of selected high-expressing genes and the ability to sexually cross transgenes to obtain multiple proteins expressed in the same plant. Using a molecular technique known as immunomodulation, genes encoding antibodies or antibody fragments are expressed in an environment, or in some cases a plant. These antibody molecules are designed to inhibit the infectivity of a pathogen or interfere with cellular metabolic processes, such as modulation of phytohormone activity.

There are, however, potential issues of concern for plant protein production: Allergic reactions to plant protein glycans and other plant antigens and plant and product contamination by mycotoxins, pesticides, herbicides and endogenous metabolites. Also, human cells adorn some antibodies with special carbohydrate molecules. Plant cells can stick the wrong carbohydrates onto a human antibody. If that happens, the maladjusted antibodies cannot stimulate the body into producing its own immune response, and they are rapidly filtered from the bloodstream.

Since 1983, progress in the field of antibody production in plants has drastically increased, and it is projected that in the near future, many of the necessary human antibodies will have an origin as a plantibody.