Circular DNA viruses identified in short-finned pilot whale and orca tissue samples.

Members of the Delphinidae family are widely distributed across the world's oceans. We used a viral metagenomic approach to identify viruses in orca (Orcinus orca) and short-finned pilot whale (Globicephala macrorhynchus) muscle, kidney, and liver samples from deceased animals. From orca tissue samples (muscle, kidney, and liver), we identified a novel polyomavirus (Polyomaviridae), three cressdnaviruses, and two genomoviruses (Genomoviridae). In the short-finned pilot whale we were able to identify one genomovirus in a kidney sample. The presence of unclassified cressdnavirus within two samples (muscle and kidney) of the same animal supports the possibility these viruses might be widespread within the animal. The orca polyomavirus identified here is the first of its species and is not closely related to the only other dolphin polyomavirus previously discovered. The identification and verification of these viruses expands the current knowledge of viruses that are associated with the Delphinidae family.

Novel Presentation of DMV-Associated Encephalitis in a Long-Finned Pilot Whale (Globicephala melas).

Cetacean morbillivirus (CeMV) is an important global cause of morbidity and mortality in cetacean populations, with four pathological presentations including non-suppurative encephalitis. We describe an unusual case of dolphin morbillivirus (DMV)-associated non-suppurative encephalitis in a long-finned pilot whale (Globicephala melas), in which the lesions were orientated on the periventricular white matter and comprised prominent multifocal syncytia formation in the absence of systemic lesions. DMV RNA was detected in brain tissue by qRT-PCR and immunohistochemistry for morbillivirus antigen yielded intense labelling of syncytia in periventricular sites, with sparse involvement of the deeper neuroparenchyma. The pattern of lesions raises the possibility of viral dissemination through the cerebrospinal fluid, as described for canine distemper virus, suggesting that similar pathogenic mechanisms may be implicated in lesion development. Further investigation is required to establish the pathogenesis of CeMV encephalitis and the behaviour of the virus within the central nervous system of cetaceans.

The genome of an influenza virus from a pilot whale: relation to influenza viruses of gulls and marine mammals.

Influenza virus A/whale/Maine/328B/1984 (H13N2) was isolated from a diseased pilot whale. Since only a partial sequence was available, its complete genome was sequenced and compared to the sequences of subtype H13 influenza viruses from shorebirds and various influenza viruses of marine mammals. The data reveal a rare genotype constellation with all gene segments derived of an influenza virus adapted to gulls, terns and waders. In contrast, the phylogenetic trees indicate that the majority of influenza viruses isolated from marine mammals derived from influenza viruses adapted to geese and ducks. We conclude that A/whale/Maine/328B/1984 is the first record of an infection of a marine mammal from a gull-origin influenza virus.

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.