In this week's New Scientist (04 Aug 01) p6 :-

Stripping cholesterol from the surface of cells (using beta cyclodextrins)
could be the key to preventing cells from being infected with HIV.
Removing this cholesterol reduces infection by 90% - James Hildreth
of Johns Hopkins, Maryland and team have found that cholesterol helps
AIDS virus enter cells.

When a newly formed virus emerges from a cell it is coated with a bit
of that cell's membrane - it's not a random bit of membrane, but taken
from the lipid raft regions so the virus steals some adhesion proteins,
enabling it to bind to other cells more easily.

The lipid rafts contain much cholesterol (for rigidity) and the beta
cyclodextrins, by removing chol., stop adhesion protein binding -
lipid rafts are therefore temporarily disrupted.