Morbillivirus infection in pilot whales: strict protein requirement drives genetic conservation

Morbillivirus infection of marine mammals has been documented across all of the world's oceans. Whilst infection is generally demonstrated using a variety of histopathological and serological techniques, where possible, the use of molecular techniques is being used to enable accurate genetic typing of virus strains through sequence analysis. Here, we present genetic data from dolphins and pilot whales affected by morbillivirus infection in the recent outbreak in the Mediterranean Sea during a six-month period from the end of October 2006 to April 2007. To date, very few studies have looked at characterizing outbreaks of morbillivirus infections in whale species at the molecular level. Here, we provide a full sequence for the haemagglutinin (H) gene from material derived from both a dolphin and a pilot whale from the 2007 outbreak in the Mediterranean Sea and show this virus to be 100% identical across the region analysed. Furthermore, we compare partial sequence data from the nucleocapsid (N) gene of the pilot whale material with previously published data and show evidence for strong protein conservation between these different isolates. Finally, we discuss the current classification of cetacean morbilliviruses as a single species.