Morbillivirus infection in cetaceans stranded along the Italian coastline: Pathological, immunohistochemical and biomolecular findings Giovanni Di Guardo a,⇑ , Cristina Esmeralda Di Francesco a , Claudia Eleni b , Cristiano Cocumelli b , Francesco Scholl b , Cristina Casalone c , Simone Peletto c , Walter Mignone d , Cristiana Tittarelli d , Fabio Di Nocera e , Leonardo Leonardi f , Antonio Fernández g , Federica Marcer h , Sandro Mazzariol i a University of Teramo, Faculty of Veterinary Medicine, Teramo, Italy b Istituto Zooprofilattico Sperimentale (IZS) delle Regioni Lazio e Toscana, Rome, Italy c IZS del Piemonte, Liguria e Valle d’Aosta, Turin, Italy d IZS del Piemonte, Liguria e Valle d’Aosta, Imperia, Italy e IZS del Mezzogiorno, Salerno, Italy f University of Perugia, Faculty of Veterinary Medicine, Perugia, Italy g University of Las Palmas, Gran Canaria, Canary Islands, Spain h University of Padua, Department of Animal Medicine, Production and Health, Padua, Italy i University of Padua, Department of Comparative Biomedicine and Food Science, Padua, Italy article info Article history: Received 8 May 2012 Accepted 28 July 2012 Available online xxxx Keywords: Morbillivirus Infection Pathogenesis Encephalitis Cetaceans Strandings Italy Mediterranean Sea abstract Morbilliviruses are recognized as biological agents highly impacting the health and conservation status of free-ranging cetaceans worldwide, as clearly exemplified by the two Dolphin Morbillivirus (DMV) epidem- ics of 1990–1992 and 2006–2008 among Mediterranean striped dolphins (Stenella coeruleoalba). After these two epidemics, morbilliviral infection (MI) cases with peculiar neurobiological features were reported in striped dolphins stranded along the Spanish coastline. Affected cetaceans showed a suba- cute-to-chronic, non-suppurative encephalitis, with brain lesions strongly resembling those found in human ‘‘subacute sclerosing panencephalitis’’ and ‘‘old dog encephalitis’’. Brain was the only tissue in which morbilliviral antigen and/or genome could be detected. Beside a case of morbilliviral encephalitis in a striped dolphin’s calf stranded in 2009, we observed 5 additional MI cases in 2 striped dolphins, 1 bottlenose dolphin (Tursiops truncatus) and 2 fin whales (Bal- aenoptera physalus), all stranded in 2011 along the Italian coastline. Noteworthy, 3 of these animals (2 striped dolphins and 1 bottlenose dolphin) showed immunohistochemical (IHC) and/or biomolecular (PCR) evidence of morbilliviral antigen and/or genome exclusively in their brain, with 1 striped dolphin and 1 bottlenose dolphin also exhibiting a non-suppurative encephalitis. Furthermore, simultaneous IHC and PCR evidence of a Toxoplasma gondii coinfection was obtained in 1 fin whale. The above results are consistent with those reported in striped dolphins after the two MI epidemics of 1990–92 and 2006–2008, with evidence of morbilliviral antigen and/or genome being found exclusively in the brain tissue from affected animals. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Morbilliviruses have been recognized, for at least 25 years, as biological agents of great concern for free-ranging cetaceans (Van Bressem et al., 2009). Before the end of 2006, a morbilliviral epi- demic was reported in pilot whales (Globicephala melas) around Gibraltar (Fernández et al., 2008) and, in the following months, in striped dolphins (Stenella coeruleoalba) and pilot whales along the Spanish Mediterranean coast (Raga et al., 2008). Apart from its milder mortality rate, this outbreak shared many similarities with the mass die-off of striped dolphins which occurred between 1990 and 1992 in the Mediterranean Sea and that was caused by a newly identified agent, Dolphin Morbillivirus (DMV) (Domingo et al., 1990, 1992; Barrett et al., 1995; Kennedy, 1998; Di Guardo et al., 2005; Di Guardo et al., 2011c; Raga et al., 2008; Van Bressem et al., 2009). The virus responsible for the 2006–2008 mortality episodes showed a close genetic proximity to the DMV strain caus- ing the dramatic die-off which took place 15 years before in the same area (Fernández et al., 2008; Raga et al., 2008; Van Bressem et al., 2009; Bellière et al., 2011). Direct evidence of morbilliviral infection (MI) has been recently reported in several striped 0034-5288/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.rvsc.2012.07.030 ⇑ Corresponding author. E-mail address: gdiguardo@unite.it (G. Di Guardo). Research in Veterinary Science xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc Please cite this article in press as: Di Guardo, G., et al. Morbillivirus infection in cetaceans stranded along the Italian coastline: Pathological, immunohis- tochemical and biomolecular findings. Res. Vet. Sci. (2012), http://dx.doi.org/10.1016/j.rvsc.2012.07.030