Viruses have shaped human history through devastating infections. In addition, virus infection may be responsible for up to 15% of cancer deaths. Nevertheless, certain viruses can be our “friends.” At the end of the 18th century, Edward Jenner used cowpox to protect humans against infection with a lethal pathogen, smallpox. Based on the effectiveness of this “vaccination” process, in the 1960s, the World Health Organization mounted a global vaccination campaign that resulted in the eradication of smallpox. In the mid-20th century, the principle of virus attenuation through adaptation to unnatural hosts was extended to cultured cells: cells from different species were used to select viruses with multiple mutations, reducing replication speed and allowing the immune system to control viral infection. Based on such a “live-attenuated” vaccine, global eradication of another viral disease, rinderpest, was recently achieved. Other global vaccination campaigns, including those against polio and measles, are progressing. In addition, subunit vaccines are proving to be effective against virus-induced cancers, preventing hepatitis B virus–induced hepatocellular carcinoma and human papilloma virus–induced cervical cancer. A new frontier is to develop viruses into anticancer weapons. Many cancers remain incurable despite recent advances in radio-, chemo-, and immunotherapy. Based on their preferential replication in tumor cells, viruses from nine families have progressed to clinical trials of oncolysis: DNA viruses include Adenoviridae, Herpesviridae, Parvoviridae, and Poxviridae and RNA viruses Paramyxoviridae, Picornaviridae, Reoviridae, Retroviridae, and Rhabdoviridae. Recently, a genetically modified herpes simplex virus 1–based oncolytic vector was approved as cancer therapeutic in the United States and Europe. What are the mechanisms supporting cancer therapy with viruses, and how can oncolytic virotherapy be improved?
How to develop viruses into anticancer weapons. (2017) PLoS Pathog 13(3): e1006190. doi:10.1371/journal.ppat.1006190