Solar-powered factories for new vaccines and antibiotics.

Chloroplasts, the green differentiation form of a group of plant cell organelles called plastids, are the sites of photosynthesis, the main energy source for life on Earth. The small circular genome of the plastid has become increasingly amenable to genetic modification, providing biotechnologists with an attractive site for the accommodation of foreign genes. In recent years, the development of optimized expression strategies has given a huge boost to the exploitation of chloroplasts in molecular farming. Exciting progress has been made with the chloroplast-based production of two particularly important classes of pharmaceuticals: vaccines and antibiotics. Extraordinarily high expression levels and the prospects of developing edible biopharmaceuticals make transgenic chloroplasts a promising platform for the production of next-generation vaccines and antimicrobials.