1. Department of Veterinary medicine and Animal productions; University of Naples Federico II; Naples Italy
2. Unit of Immunology; Environmental Microbiology and Carcinogenesis (IMEC); Science Faculty of Bizerte; University of Carthage; Bizerte Tunisia
3. Electron Microscopy and Special Virology Laboratory; Istituto Zooprofilattico Sperimentale del Lazio e della Toscana “M.Aleandri”; Rome Italy