Vaccinia virus: a versatile tool for molecular biologists.

Continued advances in genetic engineering have made possible the high-level expression of correctly processed cellular, viral and bacterial polypeptides. This article focuses on viral expression vectors and, more specifically, the vaccinia virus expression system. Vaccinia virus has been used to express a variety of proteins with useful immunogenic, catalytic or pharmaceutical properties. We discuss briefly the biology of vaccinia and its significance in the use of vaccinia as an expression vector, the variety of vaccinia systems currently in use and, finally, we summarize some recent developments which bode well for future applications of vaccinia virus technology.