Expression of bioactive human interferon-gamma in transgenic rice cell suspension cultures

We investigated the possibility of producing the therapeutic recombinant cytokine, Interferon-gamma (IFN-gamma), in transgenic rice cell (Oryza sativa, cultivar TNG67) suspension cultures. We tested expression of two vector constructs, each harboring an alphaAmy3 leader peptide and a C-terminus His 6 tag fused to a human IFN-gamma cDNA, one driven by a sucrose-starvation inducible promoter (rice alphaAmy3 promoter) and the other by a constitutive maize ubiquitin promoter, in rice cell suspensions, introduced via Agrobacterium tumefaciens. There was a significant difference in the amounts of recombinant IFN-gamma protein produced by the Ups and Amy cell lines, as cytosolic and secretory proteins respectively. Immunological analysis of IFN-gamma recombinant protein conferred a dose-dependent anti-dengue virus activity in human A549 cells, similar to the commercial product. We discuss the attractive attributes of using rice cell suspension system for the expression of therapeutic recombinant IFN-gamma.