Chronic Morbilliviral Encephalitis in a Young Striped Dolphin from Italy

Claudia Eleni,Cristina Esmeralda Di Francesco,Cristiano Cocumelli,Francesco Scholl,Roberto Speranza,Massimiliano Pennelli,Giovanni Di Guardo

doi:10.1038/npre.2010.4912.1

Abstract

AbstractA young male striped dolphin (Stenella coeruleoalba) found stranded in November 2009 was affected by a chronic non-suppurative encephalitis, with prominent mononuclear cell perivascular cuffs, neuronal degeneration, microgliosis, neuronophagia and occasional presence of multinucleate syncytia. Immunohistochemical and biomolecular investigations for Morbillivirus were positive exclusively from the brain, but not from the cerebellum nor from any other tissue, with morbilliviral antigen being detected in neurons and astrocytes. A low neutralizing antibody titer (1:10) against Morbillivirus (CDV) was also found, with no simultaneous presence of anti-Brucella antibodies.The main reason why the present case appears to be of interest is provided by its peculiar neuro-histopathologic, immunohistochemical and biomolecular features, with Morbillivirus antigenic and genomic positivity being exclusively confined to the brain of this dolphin, which may have developed a transplacentally-acquired infection.

Highlights

BETWEEN the end of 2006 and the beginning of 2007, a Morbillivirus epidemic was reported in pilot whales (Globicephala melas) around the Strait of Gibraltar (Fernández and others 2008) and, in the following months, in pilot whales and striped dolphins (Stenella coeruleoalba) along the Spanish Mediterranean coast (Raga and others 2008)
Samples of all animal’s major organs, pulmonary and mesenteric lymph nodes were fixed in 10% neutral buffered formalin and submitted to detailed histopathological investigations as well as to immunohistochemistry (IHC) against Morbillivirus. This was carried out by means of a commercially available (VMRD Inc) mouse monoclonal antibody against Canine Distemper Virus (CDV) nucleoprotein (N) antigen that recognizes the same epitope from different Morbillivirus genus members, including Dolphin Morbillivirus (DMV) (Di Guardo and others 2010)
A virus neutralization assay detecting anti-Morbillivirus (CDV) antibodies and a serum agglutination test for anti-Brucella spp. antibodies were performed on the blood serum obtained from this dolphin

Summary

Introduction

BETWEEN the end of 2006 and the beginning of 2007, a Morbillivirus epidemic was reported in pilot whales (Globicephala melas) around the Strait of Gibraltar (Fernández and others 2008) and, in the following months, in pilot whales and striped dolphins (Stenella coeruleoalba) along the Spanish Mediterranean coast (Raga and others 2008). Apart from its milder proportions, this mortality outbreak shares many similarities with the striped dolphin mass die-off that occurred throughout 1990-1992 in the Mediterranean Sea, which was caused by a newly discovered agent, named Dolphin Morbillivirus (DMV) (Domingo and others 1990, 1992, Barrett and others 1995, Kennedy 1998, Di Guardo and others 2005). Direct evidence of Morbillivirus infection has been recently reported in several striped dolphins, one pilot whale and one bottlenose dolphin (Tursiops truncatus) found stranded on the French Mediterranean coast (Keck and others 2010)

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