...And viruses.

RNA can also combat viruses, suggest investigators from the Pennsylvania State University College of Medicine in Hershey. Jin-Feng Wang and his coworkers mixed nucleotides together at random, creating a large pool of RNA strands with unknown sequences. They then isolated any strands that bound to Rous sarcoma virus, an avian virus of the same family as HIV, the AIDS virus. Those strands were mutated slightly and put through the selection process once again. By repeating this cycle many times, Wang's group evolved a small pool of RNA strands that bind efficiently to the virus. From that pool, the researchers identified five strands that significantly inhibit infection of quail eggs by the Rous sarcoma virus. Wang and his colleagues suggest that a similar strategy could be employed to evolve RNA that inhibits HIV, bacteria, or even tumor cells.