Chloroplast-derived vaccine antigens and other therapeutic proteins.

The chloroplast genetic engineering offers a number of unique advantages including high level of transgene expression, multi-gene expression in single transformation event and transgene containment due to maternal inheritance. Hyper-expression of vaccine antigens or therapeutic proteins in transgenic chloroplasts (leaves) or chromoplasts (fruits/roots) facilitates efficient oral delivery. Ability of chloroplasts to correctly fold human blood proteins with proper disulfide bridges (human serum albumin or interferons) or presence of chaperones in chloroplasts to facilitate assembly of complex multi-subunit proteins or their prokaryotic nature to express native bacterial genes (up to 46.1% total leaf protein) are attractive features for therapeutic protein production. Purification of therapeutic proteins has been achieved using novel purification strategies that do not require expensive column chromatography.