Plantibodies Make The Grade

A tin of soybeans from the local grocery store could one day provide a useful source of therapeutic antibodies. Soybean plants produce large amounts of therapeutic proteins at low cost and high yield, but it has not been clear whether these proteins work as well as those produced from mammalian cells. Kevin Whaley and co-workers at Johns Hopkins University (Baltimore, MD) have shown that a monoclonal antibody purified from plant tissue is just as stable and functional as the same antibody expressed in mammalian cell culture. Specifically, they demonstrated that a soybean-derived antibody directed against herpes simplex virus 2 (HSV-2) is equally effective as a mammalian antibody for protecting mice against genital herpes.

Because plant cells differ from mammalian cells in their ability to add sugars to proteins, it has been suggested plant-derived proteins might not make good human therapeutics. Whaley decided to test this by characterizing and comparing the physical properties of a humanized anti HSV-2 monoclonal antibody derived from either soybean or mammalian cells. They found that soybean-derived antibodies are comparable in terms of their ability to remain stable in human reproductive fluids, diffuse in cervical mucus, and protect mice against HSV-2 infection. They also report that the affinity of the plant monoclonal for HSV did not differ from that of the mammalian expressed antibody, and there was no apparent difference in their ability to neutralize HSV-2. The results provide compelling support for the feasibility of plant-derived human therapeutics in the treatment of sexually transmitted and other diseases.

For more information: Kevin J. Whaley, Department of Biophysics, The John Hopkins University, 3400 N. Charles Street, Jenkins Hall, Baltimore, MD 21218 Tel: 410-516-7260 Fax: 410 516 6597 Email: whale@jhu.edu.