The finding could turn out to be very important in developing treatments for AIDS, he said, but more work needs to be done before scientists know how signficiant this discovery is.
The findings are being reported in Science, one of the nation's leading scientific journals.
The AIDS virus can have a devastating impact when it attacks the nervous system. It can cause AIDS Dementia Complex, whose symptoms include forgetfulness, slurred speech, clumsiness and the inability to concentrate.
In its more severe forms it can cause incoherence, movement disorders, paranoia, other psychiatric symptoms and rapid brain deterioration leading to death.
While only 3 to 5 percent of people with AIDS show signs of AIDS Dementia Complex initially, more than 60 percent develop symptoms and signs of the disease. Experts believe that these neurological problems will become even more commonplace as physicians make advances in treating AIDS infections and patients live longer.
In their study, the Penn scientists identified a molecule commonly found on the surface of some nerve and brain cells that appears to be a receptor - or docking point - where viruses can enter the cell. The name of the molecule is GalactosylCeramide or GalCer.
"Identification of receptors is essential to understanding the method of infection and could lead to effective strategies for blocking the spread of infection throughout the nervous system," said Shama Bhat, a Penn scientist who co-authored the paper.
The other authors of the paper include Penn scientists Janet Harouse, Steven Spitalnik, Mark Laughlin, Kelly Stefano and Donald H. Silverberg.