The IE2 promoter/enhancer region from mouse CMV provides high levels of therapeutic protein expression in mammalian cells

Protein expression in mammalian cells is key for the production and manufacturing of bio‐therapeutics with human‐like properties and activities. As a molecular basis for reaching high protein expression levels, efficient promoter/enhancer systems are a prerequisite. Here we identify a novel enhancer from the mouse cytomegalovirus (CMV) immediate early 2 (IE2) region as a strong expression‐promoting element. We further demonstrate its activity in bi‐directional promoter architecture and apply it to generate production clones for IL‐18BP, a protein with therapeutic indications in autoimmune diseases. These data show that the IE region from mouse CMV, and the IE2 enhancer/promoter in particular, have a broad potential for application in novel gene expression systems for research, development, and manufacturing of protein drugs. Biotechnol. Bioeng. 2007;96: 106–117. © 2006 Wiley Periodicals, Inc.