The cloning methodology. (A) Design of cassette A and B. Creation of the AB fusion cassette by (A) a C-terminal fusion to cassette A and (B) a N-terminal fusion to cassette B. (D) Schematic diagram of the pCfvtx vector. pTriEx1.1-Hygro (Novagen) was chosen as the base vector because it allows expression in both prokaryotic and eukaryotic cells.