1. International Centre for Diarrhoeal Disease Research; Bangladesh, GPO Box 128 Dhaka 1000 Bangladesh
2. Department of International Health, School of Hygiene and Public Health; Johns Hopkins University; Baltimore Maryland 21205 U.S.A.
3. Center of Marine Biotechnology; University of Maryland Biotechnology Institute; Baltimore Maryland 21202 U.S.A.
4. Department of Cell Biology and Molecular Genetics; University of Maryland; College Park Maryland 20742 U.S.A.