Dolphin Morbillivirus in a Cuvier’s Beaked Whale (Ziphius cavirostris), Italy

Abstract

Dolphin morbillivirus (DMV) has caused several mortality events in Mediterranean striped (Stenella coeruleoalba) and bottlenose (Tursiops truncatus) dolphins populations since 19; in the last 5 years, the virus was reported to infect new hosts in this basin, such as fin whales (Balaenoptera physalus), sperm whales (Physeter macrocephalus), and even a harbor seal (Phoca vitulina). Very recently, a calf Cuvier’s beaked whale (Ziphius cavirostris) calf stranded on the Southern Italian coastline with mild pathological findings suggestive of morbilliviral infection, received the first confirmation of DMV infection in this species by biomolecular evidences on lung tissue. This new cross-species infection report, along with 19% of the cetaceans specimens examined by the Italian Stranding Network being found positive to DMV, support the hypothesis of an endemic circulation of this virus among Mediterranean cetaceans.

Circulation of a novel strain of dolphin morbillivirus (DMV) in stranded cetaceans in the Mediterranean Sea

“…In turn, the N gene sequence showed 98.5–97.9% nucleotide identity with the sequences obtained from a white-beaked dolphin ( Lagenorhynchus albirostris ) stranded on the Fresian coast of Germany in 2007 (EF469546) 31 , from a Cuvier’s beaked whale (KX237510) 24 , from a fin whale (KU977449) 22 stranded on the Italian coast between 2011 and 2013, and from a striped dolphin and a long-finned pilot whale stranded on the Mediterranean coast of Spain in 2007 (HQ829973, HQ829972) 32 (Supplementary Table S3).…”

“…Two more epizootics occurred in the Mediterranean Sea in 2007 and 2011, when more than 200 and 50 striped dolphins died, respectively 15–17 . DMV infections have been reported on the Italian coastline of the Mediterranean Sea in different cetacean species, including fin whale ( Balaenoptera physalus ), sperm whale ( Physeter macrocephalus ), Cuvier’s beaked whale ( Ziphius cavirostris) , striped dolphin and bottlenose dolphin 18–24 . This suggests that DMV remains a major threat to cetaceans.…”

Genetic heterogeneity of dolphin morbilliviruses detected in the Spanish Mediterranean in inter-epizootic period

“…However, systemic cases were found in Italy in 2011 to 2013 in one fin whale and in numerous sperm whales due to DMV strains closely related to the viruses responsible for the 2007 and 2011 Spanish outbreaks [ 22 , 24 ], and DMV-positive striped dolphin mass mortality also occurred in Italy in 2013 that could possibly be related to these previous Mediterranean strains [ 21 ]. Thus, as already proposed [ 3 , 16 ] there appears to be endemic viral circulation within the Mediterranean, possibly within the abundant striped dolphin population, although the potential roles of whales in the transmission and maintenance of DMV strains, possible in principle given the reports of pilot whales and a Cuvier’s beaked whale ( Ziphius cavirrostris ) infected with DMV [ 6 , 20 , 38 ], appear unlikely given the low density of these species in the Mediterranean. The fact that the Valencian Community was the epicenter of the previous three DMV epizootics in the Mediterranean makes conceivable that this region could harbor local DMV reservoirs, although this possibility requires further investigation, since other factors like abundance of striped dolphins in the area, and efficient and active surveillance networks may be responsible for the early detection of the epizootics in this region.…”

Cetacean morbillivirus, a journey from land to sea and viceversa

“…In this respect, while a CeMV isolate from the Southern Hemisphere that was identified almost simultaneously in Guyana dolphins (Sotalia guianensis) along the Atlantic coast of Brazil as well as in Indo-Pacific bottlenose dolphins (Tursiops aduncus) from Western Australia [15-17] appears to be the one most closely related to RPV among the 5 hitherto defined CeMV strains [3], it should be once again recalled that fatal cases of infection caused by Dolphin Morbillivirus (DMV, a CeMV strain) have been recently reported in Italy among Eurasian otters, an endangered wild mammal species with a mixed water-terrestrial ecology [7]. Furthermore, starting from 2011, DMV has shown a considerable expansion of its host range in the Western Mediterranean Sea, with lethal episodes of infection having been reported in fin whales as well as among mass-stranded sperm whales [4,5,18], while deadly cases of DMV infection have also been described in a Cuvier's beaked whale (Ziphius cavirostris) individual [19] and, surprisingly, even in a captive harbour seal [6].…”