Gertrude Belle Elion was a twentieth-century scientist in the US who researched the structure of viral DNA to help develop anti-viral medications. For her work on drug development, Elion was a co-recipient of the 1988 Nobel Prize in Physiology or Medicine, even though she lacked a PhD or MD. In the 1970s, Elion helped to develop acyclovir, an early anti-viral medication, alongside a team of other researchers. Acyclovir was one of the first selective medications to effectively treat herpes simplex virus types 1 and 2, or HSV-1 and HSV-2. Those are common viruses that can be transmitted via close contact or sexual intercourse, and cause sores on the mouth and genitals. The medications that Elion helped develop were also some of the first to specifically inhibit the replication of viral DNA. By creating medications like acyclovir based on her knowledge of chemistry and biology, rather than through trial and error, Elion helped create a new model for drug development, in addition to making an effective treatment for herpes, which afflicts billions of people globally, and can cause life-threatening illness in infants.