ABSTRACT
Vaccinia virus ( VACV) has been widely used in humans for the eradication of small-pox. Since its natural ability of selective infection and replication in tumor cells without harming the normal tissue, VACV becomes a promising candidate in cancer therapy. In recent years, a variety of strategies have been successfully applied to further enhance the tumor selectivity and anti-tumor efficacy of VACV. These engineered VACVs, such as JX-594, have shown promising results in cancer treatment and have made re-markable progress in clinical trials. This review first briefly introduces the oncolytic VACV, and then focuses on the strategies applied in VACV engineering. We also discuss the main challenges and the future directions in the development of oncolytic VACV.