The Scientist profiles one of many initiatives to engineer viruses to destroy cancer: "He had been studying ways in which pox viruses evade the immune system and looking at ways to disable them. ... He had pox viruses from China and from Russia and India that were used as vaccines. He had elephant pox, camel pox, you name it; so we could immediately tap into that treasure trove and try to identify the best anticancer strains ... Of particular interest [was] a form of vaccinia known as extracellular enveloped virus (EEV), which appears tailored for long-distance travel through the blood stream and seems resistant to complement and neutralizing antibodies. He saw EEV as a key to achieving systemic spread of a therapeutic virus, in order to hunt down distant tumor metastases. ... Advances in bioengineering have provided the means to sharpen viral activity, fine tuning its targeting and adding transgenes that might aid in the destruction of cancer. Kirn is eager to get these infectious agents into humans. ... Even with more than a century of work on oncolytic viruses that hasn't spurred a major breakthrough, Kirn says that things are different now. The goals of research are more sharply defined, and the questions being asked in trials are more specific. Instead of merely documenting the effects of available or slightly-modified viruses, new candidate viruses can meet specific criteria."