CONTACTS If you wish to have more information concerning our journal, please write to: Desk Editor: Michèle Roa email: mroa@pasteur.fr Editorial Coordinator: Géraldine Camus email: microbes@pasteur.fr Institut Pasteur Publications Service 28 rue du Dr. Roux 75724 Paris cedex 15, France fax : 33 1 45 68 81 84