TNF and neoplasm: Cargo has included oncolytic viruses such as the H-1 parvovirus and vesicular stomatitis virus (VSV), prodrug converting enzyme genes including herpes simplex virus thymidine kinase (HSV-TK) and cytosine deaminase (CD), transgenes that target the tumor microenvironment such as tumor necrosis factor (TNF), and the secretory version of TNF-related apoptosis-inducing ligand (S-TRAIL).