Alphaviruses as vectors for gene delivery

Alphavirus vectors have become an important complement to the systems available for transient expression of cloned sequences in cell culture and in vivo. They express foreign sequences from cytoplasmically self-replicating RNA, which can be delivered into the cell either as RNA or DNA. This article outlines some of the properties of alphavirus expression systems, and discusses the pros and cons underlying their present use in basic research and for in vivo applications.