The search for gene function has created the need for a system that can express and screen large pools of proteins in order to find binding partners for orphan ligands or receptors. Cytos Biotechnology AG has published a method of identifying gene function based on the use of alphavirus, a single-stranded RNA virus, which allows high protein expression levels that facilitate mRNA isolation, gene cloning and screening.

Using its alphavirus vector, Cytos (Zurich, Switzerland) can express full length cDNAs of interest in RNA plasmids and transfect a range of host cells. The DELphi (discovery of localized proteins) system