PT - JOURNAL ARTICLE AU - Yasser Hassan AU - Sherry Ogg TI - Expression of Pokeweed Antiviral Protein Isoform S1 (PAP-S1) and of Ricin-A-Chain/PAP-S1 novel fusion protein (RTA/PAP-S1) in <em>Escherichia coli</em> and their comparative inhibition of protein synthesis <em>in vitro</em> AID - 10.1101/137919 DP - 2017 Jan 01 TA - bioRxiv PG - 137919 4099 - http://biorxiv.org/content/early/2017/05/14/137919.short 4100 - http://biorxiv.org/content/early/2017/05/14/137919.full AB - Fusion protein therapeutics engineering is advancing to meet the need for novel medicine. Herein, we further characterize the development of novel RTA &amp; PAP-S1 antiviral fusion proteins. In brief, RTA/PAP-S1 and PAP-S1/RTA fusion proteins were produced in both cell free and E. coli in vivo expression systems, purified by His-tag affinity chromatography, and protein synthesis inhibitory activity assayed by comparison to the production of a control protein, CalmL3. Results showed that the RTA/PAP-S1 fusion protein is amenable to standardized production and purification and has both increased potency and less toxicity compared to either RTA or PAP-S1 alone. Thus, this research highlights the developmental potential of novel fusion proteins with reduced cytotoxic risk and increased potency.