1. Institute for Research in Biomedicine, 6500 Bellinzona, Switzerland.
2. Institute of Medical Microbiology, University Hospital Essen, 45122 Essen, Germany.
3. Department of Veterinary Pathology, Hygiene and Public Health, University of Milan, 20100 Milan, Italy.
4. Department of Biology and Genetics for Medical Sciences, University of Milan, 20100 Milan, Italy.
5. Department of Pharmacological Sciences, University of Milan, 20100 Milan, Italy.
6. Department of Medical Pharmacology, CNR Institute of Neuroscience, University of Milan, 20100 Milan, Italy.