1. University of PennsylvaniaDepartment of MedicineDivision of Infectious Disease536 Johnson PavillionPhiladelphiaPA19104U.S.A.
2. Swiss Federal Institute of TechnologyDepartment of NeurobiologyZurichSwitzerland
3. Hamilton CollegeBiology Department198 College Hill RdClintonNY13323U.S.A.
4. National Institutes of HealthNational Institute of Dental ResearchBldg 30, Rm 407, 9000 Rockville PikeBethesdaMD20892U.S.A.