Shining light on viral diseases and cancer.

A scientist at Washington University literally has shone new light on a potential way to treat viral diseases and cancer. John-Stephen Taylor, associate professor of chemistry has created a modified piece of DNA that can be fragmented when exposed to ultraviolet light by laser. Once broken into two pieces, the longer piece of the modified DNA binds to a target site - virus or cancer-and makes it dysfunctional. The breakthrough provides scientists new ways to battle viruses and cancers and may change or even displace chemotherapy.

Taylor incorporated the modified DNA piece, which he calls a photocleavable subunit, into another short piece by automated DNA synthesis. When light is shone on the DNA molecule bearing the photocleavable piece, the DNA strand falls apart into a long and a short fragment. The sequence of the long fragment is designed so that it matches a sequence in another DNA molecule to which it binds, changing its genetic message.

Potential therapeutic uses for Taylor's building block are based on a strategy called antisense, whereby matching genetic sequences bind to specific messenger RNA molecules, inactivating their genetic message. Because...