1. Département
de Biologie Cellulaire, Université de Genève, Sciences
III, 30 Quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland
2. Swiss Tropical and Public Health Institute, Socinstrasse 57, CH-4051 Basel, Switzerland
3. University of Basel, Petersplatz
1, CH-4001 Basel, Switzerland