1. Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni, 23/A, 07100 Sassari, Italy
2. GSK Vaccine Institute for Global Health GSK, Via Fiorentina, 1, 53100 Siena, Italy
3. Department of Biomedical Sciences, Section of Microbiology and Virology, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy
4. Department of Chemistry, Biomedicinskt Centrum, BMC, Uppsala University, Box 576, 75123 Uppsala, Sweden
5. Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy