Retroviruses are like that in the human body.
They sneak into our blood stream, hide inside our immune system undetected and then wait until it's time to strike. For humans, however, it's problematic. Viruses cause everything from AIDS to herpes zoster the sniffles to certain cancers. Their complex structure makes them rewarding research subjects. With a grant from the American Cancer Society, he aims to develop a vaccine for the virus within three years.