Medical Molecular Pharming: Expression of Antibodies, Biopharmaceuticals and Edible Vaccines via the Chloroplast Genome

Abstract

The daily income of nearly one billion people is less than one U.S. dollar. However, the annual cost of interferon therapy for leukemia, metastasizing carcinoma, Karposi sarcoma or viral hepatitis is $26,000. Among 180 million people infected with hepatitis C virus, a large majority of them have severe cirrhosis. Currently there is no vaccine available for hepatitis C. The annual requirement of Insulin like Growth Factor I, per cirrhotic patient is 600 mg and the current cost per mg is $30,000. In contrast, chloroplast-derived biopharmaceuticals should be inexpensive to produce and store, easy to scale up for mass production, and safer than those derived from animals or humans. Chloroplast genetic engineering is an environmentally friendly approach and offers biological containment of transgenes. Expression of thousands of copies of transgenes per cell via chloroplast genomes has yielded the highest level of foreign proteins ever reported in transgenic plants. Chloroplast transgene expression is also free of position effect and gene silencing, frequently encountered in nuclear transgenic plants. Oral delivery of medicine, via food, should eliminate the purification steps that usually account for most of production costs. Edible vaccines may be the only practical solution to combat bioterrorism. The successful engineering of tomato chromoplasts for high level transgene expression in fruits, coupled to hyper-expression of vaccine antigens and the use of plant-derived antibiotic free selectable markers augur well for oral delivery of edible vaccines or biopharmaceuticals that are currently beyond the reach of those who need them most. This article provides recent developments in the expression of antibodies, biopharmaceuticals edible vaccines via the chloroplast genome and also addresses possible environmental advantages.