1. International Partnership for Microbicides, Silver Spring, Maryland 20910.
2. The Population Council, New York, New York 10017.
3. University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104.
4. Tibotec, Mechelen, Belgium.
5. University of Ghent, Ghent, Belgium.
6. Particle Sciences, Inc., Bethlehem, Pennsylvania 18017.