As part of the infection process, a key component of HIV undergoes a kind of shape-shifting that allows the virus to enter into human cells, researchers report. The discovery could provide leads for an AIDS vaccine or other drug treatments, they said.Structural biologists at Children’s Hospital Boston and Harvard Medical School in Boston, have found that a protein called gp120 in the virus’ outer membrane will bind to a cell targeted for infection, then undergo a shape change.That change triggers a set of actions that enable HIV’s outer membrane to fuse with the target cell’s membrane.Knowing how the protein binds and then changes shape could allow doctors to inhibit HIV -- if they can find a drug that keeps that change from happening, lead researcher Stephen Harrison, an investigator at the Howard Hughes Medical Institute, explained in a prepared statement."The findings also will help us understand why it’s so hard to make an HIV vaccine, and will help us start strategizing about new approaches to vaccine development,” Harrison said.The research is published in the Feb. 24 issue of Nature.