1. World Health Organization Immunology Research and Training Centre, Department of Pathology, University of Geneva, CMU, 1211 Geneva 4, Switzerland,
2. Swiss Tropical Institute, 4051 Basel, Switzerland,
3. and
Polypeptide Synthesis Department, Eniricerche, 00015 Monterotondo, Italy
4. Swiss Tropical Institute, Field Laboratory, Ifakara, Tanzania,