 The modification allowed the recombinant virus to specifically infect cancer cells that expressed the corresponding proteases, which can cleave a modified protease cleavage site.The interferon production and / or response system often malfunctions in malignant cells; therefore, they are much more vulnerable to infection with oncolytic viruses compared to normal cells.Thus, cells belonging to three human cell lines, originated from variable malignancies, such as U937, Namalwa, and A549, retain their ability to become infected with SeV even after treatment with type 1 IFN.