Transient Gene Expression and Purification of a MouseDerived AntiAllergy Fusion Protein

To improve the transient gene expression of a mousederived antiallergy fusion protein (mAAFP) in 5 L bioreactor, feeding and mild hypothermia were adopted together to provide sufficient nutrition for cell growth and extend the production duration. Firstly, two different expression vectors of pCImAAFP and pIDmAAFP were transiently transfected in CHOS cells with an optimal transient transfection protocol and a better level of mAAFP expression was reached when using pIDmAAFP as an expression vector. Transient gene expression (TGE) was conducted in 1.3 L bioreactor, with combined use of fedbatch and mild hypothermic culture, so the expression level of mAAFP was increased 8fold compared with batch culture. Finally, the TGE process was carried out in a 5 L bioreactor and a high expression level of 25 mg/L was achieved. mAAFP was subsequently purified by rProteinA Sepharose Fast Flow. The obtained mAAFP was identified by SDSPAGE and Western blot. This work provided the necessary basis to assay mAAFP efficacy in mouse later on.