Arlen, Philip A.Falconer, ReginaCherukumilli, SriCole, AmyCole, Alexander M.Oishi, Karen K.Daniell, Henry2023-05-222023-05-222007-07-012019-11-14https://repository.upenn.edu/handle/20.500.14332/9024Type I interferons (IFNs) inhibit viral replication and cell growth and enhance the immune response, and therefore have many clinical applications. IFN-α2b ranks third in world market use for a biopharmaceutical, behind only insulin and erythropoietin. The average annual cost of IFN-α2b for the treatment of hepatitis C infection is $26 000, and is therefore unavailable to the majority of patients in developing countries. Therefore, we expressed IFN-α2b in tobacco chloroplasts, and transgenic lines were grown in the field after obtaining United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) approval. Stable, site-specific integration of transgenes into chloroplast genomes and homoplasmy through several generations were confirmed. IFN-α2b levels reached up to 20% of total soluble protein, or 3 mg per gram of leaf (fresh weight). Transgenic IFN-α2b had similar in vitrobiological activity to commercially produced PEG-Intron™ when tested for its ability to protect cells against cytopathic viral replication in the vesicular stomatitis virus cytopathic effect (VSV CPE) assay and to inhibit early-stage human immunodeficiency virus (HIV) infection. The antitumour and immunomodulating properties of IFN-α2b were also seen in vivo . Chloroplast-derived IFN-α2b increased the expression of major histocompatibility complex class I (MHC I) on splenocytes and the total number of natural killer (NK) cells. Finally, IFN-α2b purified from chloroplast transgenic lines (cpIFN-α2b) protected mice from a highly metastatic tumour line. This demonstration of high levels of expression of IFN-α2b, transgene containment and biological activity akin to that of commercial preparations of IFN-α2b facilitated the first field production of a plant-derived human blood protein, a critical step towards human clinical trials and commercialization.This is the peer reviewed version of the following article:Arlen, P. A., Falconer, R., Cherukumilli, S., Cole, A., Cole, A. M., Oishi, K. K., & Daniell, H. (2007). Field production and functional evaluation of chloroplast-derived interferon-α2b. Plant Biotechnology Journal, 5(4), 511–525. http://doi.org/10.1111/j.1467-7652.2007.00258.x, which has been published in final form at http://doi.org/10.1111/j.1467-7652.2007.00258.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving (http://olabout.wiley.com/WileyCDA/Section/id-820227.html#terms).antitumourantiviralgene containmentmolecular ‘pharming’plant-made cytokineDentistryArticle