The other novel Southern hemisphere CeMV-2 strain was first described from a Guiana dolphin ( Sotalia guianensis) in Brazil 4. One of the CeMV-2 strains was first described in two Indo-Pacific bottlenose dolphins ( Tursiops aduncus) from Western Australia 5 and was later believed to be a major contributor to an unusual mortality event in Southern Australia Indo-Pacific bottlenose dolphins in 2013 where CeMV nucleotide similarity was 99.7% when compared to the CeMV strain initially described from Western Australia 8.
These six strains have been clustered into two lineages the CeMV-1 lineage that includes DMV, PMV, PWMV and BWMV and the CeMV-2 lineage that is represented by the two Southern hemisphere strains 7. More recently, three other strains of CeMV have been described, two from the Southern Hemisphere (Western Australia and Brazil) and the beaked whale morbillivirus (BWMV) from Hawaii 4, 5, 6. Three strains of CeMV are well recognized, including the first description of porpoise morbillivirus (PMV) in two harbor porpoises ( Phocoena phocoena) 1, dolphin morbillivirus (DMV) that was identified for the first time from striped dolphins ( Stenella coeruleoalba) 2 and pilot whale morbillivirus (PWMV) that was initially identified from a long-finned pilot whale ( Globicephala melas) 3. As Fraser’s dolphins are a pelagic species that infrequently strand, a novel strain of CeMV may be circulating in the central Pacific that could have additional population impacts through transmission to other small island-associated cetacean species.Ĭetacean morbillivirus (CeMV) of the family Paramyxoviridae and the genus Morbillivirus, has been associated with lethal outbreaks worldwide and represents one of the greatest infectious disease threats to cetaceans. The resulting 248 bp P gene had the highest nucleotide identity to porpoise morbillivirus in Northern Ireland and the Netherlands and to a stranded Guiana dolphin ( Sotalia guianensis) in Brazil (66.9%). The resulting 559 bp L gene sequence had the highest nucleotide identity (77.3%) to porpoise morbillivirus from Northern Ireland and the Netherlands. Samples of the cerebellum, lung, liver, spleen and lymph nodes were positive for morbillivirus using a reverse transcription-polymerase chain reaction. Transmission electron microscopy of infected cell cultures also revealed syncytial cells with intracytoplasmic and intranuclear inclusions of viral nucleocapsids, consistent with the ultrastructure of a morbillivirus. Cerebellum and lung tissue homogenates were inoculated onto Vero.DogSLAMtag cells for virus isolation and cytopathic effects were observed, resulting in the formation of multinucleated giant cells (i.e., syncytia).
Histopathological findings included intranuclear inclusions in bile duct epithelium, lymphoid depletion, rare syncytial cells and non-suppurative meningitis. We report a novel morbillivirus from a Fraser’s dolphin ( Lagenodelphis hosei) that stranded in Maui, Hawaii in 2018 that is dissimilar to the beaked whale morbillivirus previously identified from Hawaii and to other CeMV strains. Cetacean morbillivirus (CeMV) is a global threat to cetaceans.