With the help of x-ray crystallography, a technique that enables scientists to deduce the positions of individual atoms in a structure, Luger and her collaborator Kenneth Kaye of Harvard Medical School have just discovered the devious way in which the Kaposi virus spreads: It piggybacks onto segments of chromatin, a protein- and DNA-containing structure inside the cell's nucleus, forcing the cell to produce more viral genes every time it copies its own DNA.

Photo Illustrations: Gregory Bowman