The Semliki Forest virus system: Receptor expression and scale-up

The highly efficient Semliki Forest virus (SFV) system has been applied to express several recombinant 7TM receptors and ligand-gated ion channels. High affinity binding and functional coupling to G proteins were obtained for the receptors. The ligand-gated ion channels showed high specific binding activity and high-amplitude electrophysiological responses in whole-cell patch clamp recordings. The rapid and simple generation of high titre virus stocks has made the SFV System also useful for site-directed mutagenesis studies. The broad host range of SFV has allowed studies of recombinant proteins in a wide variety of cell lines and primary cell cultures. Scale-up technology for SFV has Been established. Recombinant SFV particles containing a his-tagged mouse serotonin 5-HT3 receptor gene were used to Infect suspension cultures of BHK cells at reactor scale (11.5 l). Receptor yields of 15 mg (B-max values of 52 pmol mg(-1)) were obtained. The receptor was solubilised, isolated to high purity and subjected to structure-function studies.