Salivary safeguard
American scientists say that they now know why HIV does not spread through saliva: a protein called SLPI in human saliva acts as a "guard", binding to white blood cells and stopping them from becoming infected (New Scientist, Vol 145, No 1964).
Researchers led by Sharon Wahl and Tessie McNeely of the National Institute of Dental Research in Bethesda, Maryland, found that if SLPI is eliminated from saliva, the fluid loses most of its ability to block HIV entry. They are now trying to understand how SLPI works and identify the molecules with which it interacts. "This could provide clues to designing new drugs to combat AIDS," says Wahl.