This product is a lacZ encoding oncolytic herpes simplex virus, which is based on HSV-1 with ICP34.5 and UNG deleted. ICP34.5 protein, is important for viral replication, viral exit from infected cells, prevention of the premature shut-off of protein synthesis in the infected host, and neurovirulence. Uracil DNA glycosylase (UNG, UDG) is the most abundant cellular enzyme encoded by the UL2 gene for removing uracil generated by hydrolytic deamination of cytosine or misincorporation of dUTP. The deletion of UDG may have contributed to lower rates of DNA repair during the passage or selection conditions. This product can be used in oncolytic virotherapy research and further recombinant HSV construction.