Gianfranco Gabai1, Massimo Amadori2, Christopher H Knight3, Dirk Werling4. 1. Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Italy. Electronic address: gianfranco.gabai@unipd.it. 2. Laboratory of Cellular Immunology, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Brescia, Italy. 3. Institute of Veterinary and Animal Sciences, University of Copenhagen, Denmark. 4. Department of Pathology and Population Sciences, Royal Veterinary College, London, UK.