In a preferred embodiment of the invention, the promoter is a cytomegalovirus (CMV) promoter, a MDOT promoter, a rous-sarcoma virus (RSV) promoter, a murine leukemia virus (MLV) promoter, a mouse mammary tumor virus (MMTV) promoter, an ovalbumin promoter, a lysozyme promoter, a conalbumin promoter, an ovomucoid prom