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The sub-adult male Fraser's dolphin (Lagenodelphis hosei) that stranded at Olowalu, Maui, Hawaii. Photo courtesy of Cindy Kern.
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Cetacean morbillivirus (CeMV) is a global threat to cetaceans. 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. Histopathological findings included intranuclear inclus...
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... stranded dolphin was in good body condition, had a total body length of 2.04 m, weighed 183.5 kg and was an immature male ( Fig. 1). Gross necropsy findings included cookie cutter shark bites and abrasions up to 30 cm in length along the lateral sides of the body that are likely associated with coming across reef or rocks during the stranding event. Multiple abrasions were also documented on the dorsal fluke surface. The left eye was intact, but a bleeding open ...
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... Cetacean morbillivirus (CeMV) is an enveloped virus with nonsegmented, negative sense single-stranded RNA (ssRNA) genome that belongs to the genus Morbillivirus (species Morbillivirus ceti) of the family Paramyxoviridae (subfamily Orthoparamyxovirinae) within the order Mononegavirales (Seki and Takeda, 2022). CeMV infects a wide range of marine mammal species, is globally widespread and evolutionarily distinct into two lineages and six recognized strains, named after the species in which they were first identified, including the dolphin morbillivirus (DMV), the porpoise morbillivirus (PMV), the beaked whale morbillivirus (BWMV), the pilot whale morbillivirus (PWMV), the Guyana dolphin morbillivirus (GDMV) and the recently characterized Fraser´s dolphin morbillivirus (FDMV) (Jo et al., 2018;West et al., 2021). All CeMV strains are deemed as highly pathogenic, causing an acute respiratory disease that often results in fatal outcome due to the induced profound immunosuppression, or may otherwise evolve into chronic infection with late neurological manifestations (Van Bressem et al., 2014). ...
Cetacean morbillivirus (CeMV) is an enveloped, non-segmented, negative-stranded RNA virus that infects marine mammals, spreading across species and causing lethal disease outbreaks worldwide. Among the eight proteins encoded by the CeMV genome, the haemagglutinin (H) glycoprotein is responsible for the virus attachment to host cell receptors. CeMV H represents an attractive target for antiviral and diagnostic research, yet the elucidation of the molecular mechanisms underlying its role in infection and inter-species transmission was hampered thus far due to the unavailability of recombinant versions of the protein. Here we present the cloning, expression and purification of a recombinant CeMV H ectodomain (rH-ecto), providing an initial characterization of its biophysical and structural properties. Sodium dodecyl sulphate - polyacrylamide gel electrophoresis (PAGE) combined to Western blot analysis and periodic acid Schiff assay showed that CeMV rH-ecto is purifiable at homogeneity from insect cells as a secreted, soluble and glycosylated protein. Miniaturized differential scanning fluorimetry, Blue Native PAGE and size exclusion chromatography coupled to multiangle light scattering revealed that CeMV rH-ecto is globularly folded, thermally stable and exists in solution in the oligomeric states of dimer and multiple of dimers. Furthermore, negative stain electron microscopy single particle analysis allowed us to delineate a low-resolution molecular architecture of the CeMV rH-ecto dimer, which recapitulates native assemblies from other morbilliviral H proteins, such as those from measles virus and canine distemper virus. This set of experiments by orthogonal techniques validates the CeMV rH-ecto as an experimental model for future biochemical studies on its structure and functions.
... To investigate this question, we conducted a simulated seawater dilution experiment with feces sampled from the gastrointestinal tract of a stranded Fraser's dolphin (Lagenodelphis hosei) that was positive for CeMV. The strain of morbillivirus in this animal was determined to be novel (Fraser's dolphin morbillivirus) and dissimilar to the beaked whale morbillivirus previously identified in Hawaiʻi (West et al., 2013(West et al., , 2021. ...
... Seawater was simulated by dissolving 35 g of sodium chloride in 965 g of distilled water (35‰). Brain tissue from the same animal was used as a positive control (West et al., 2021). Distilled water and feces from the Fraser's dolphin that stranded in 2022 and tested negative for morbillivirus in a suite of organ samples were used as no template and negative controls. ...
... Morbillivirus RNA was previously detected in cerebellum, lung, liver, spleen, and lymph node tissues of the stranded Fraser's dolphin during the initial screening for CeMV. The dolphin was diagnosed with interstitial pneumonia, meningitis, and lymphoid depletion characteristic of acute CeMV disease (West et al., 2021). CeMV is typically associated with respiratory and neurological disease, but the presence of the virus has been demonstrated in multiple organs during systemic infections (e.g., Van Bressem et al., 2014). ...
... Co-infections were present among some of the BWCV positive individuals ( Table 2). The initial Longman's beaked whale, a sperm whale, a Blainville's beaked whale, and a Fraser's dolphin were co-infected with cetacean morbillivirus (West et al., 2013;West et al., 2015;Jacob et al., 2016;West et al., 2021). In addition to morbillivirus, an alpha herpesvirus was present in the Longman's beaked whale and Brucella ceti in the neonate sperm whale (West et al., 2013;West et al., 2015). ...
... Co-infection by other pathogens is common with other circoviruses (Yang et al., 2015). Cetacean morbillivirus, a potentially fatal disease, was found in four of the BWCV cases from the Pacific Islands, including the initial Longman's beaked whale case, as well as a neonate sperm whale, a subadult Blainville's beaked whale, and a Fraser's dolphin infected with a novel morbillivirus strain (West et al., 2013;West et al., 2015;Jacob et al., 2016;West et al., 2021). Fatally disseminated toxoplasmosis was found in an adult spinner dolphin that was positive for BWCV (Landrau-Giovannetti et al., 2022). ...
... Brucella was present in several of the tissues of the neonate sperm whale and likely caused the pathology observed, and an alpha herpesvirus was also described in the initial Longman's beaked whale, making both of these cases tri-infections (West et al., 2013;West et al., 2015). The individuals with BWCV and confirmed co-infections had respiratory disease, lymphoid depletion and poor body condition indicative of wasting (Landrau-Giovannetti et al., 2020;Landrau-Giovannetti et al., 2022;West et al., 2021). Conversely, other positive cases had no apparent pathology observed. ...
The first cetacean circovirus, beaked whale circovirus (BWCV), was recently reported in a Longman’s beaked whale ( Indopacetus pacificus ) stranded in Hawai‘i and represents an emergent disease with unknown population impacts. In other species, circovirus infection may cause mortality or opportunistic co-infection by other pathogens. We report on a targeted surveillance of stranded cetaceans in the Pacific basin, including archived beaked whale species, strandings where pathological findings suggested disease presence, mass stranded animals, and additional individuals to represent a broad range of Hawaiian cetacean species. Archived tissues primarily from the brain, kidney, liver, lung, spleen, and lymph nodes of individuals stranded between 2000 and 2020 (n=30) were tested by PCR for the presence of BWCV. Suspect positive tissue amplicons were confirmed as BWCV through sequencing. Of the screened individuals, 15 animals tested positive in one or more tissues, with a single striped dolphin ( Stenella coeruleoalba ) testing positive in all six tissues. The highest rate of detection among positive cases was found in the brain (69%), followed by lymph (67%) and lung tissues (64%). Additionally, co-infections of cetacean morbillivirus (n=3), Brucella ceti (n=1), and Toxoplasma gondii (n=1) were found among the positive cases. These results expand the potential host range for BWCV into ten additional odontocete species. New host species include a dwarf sperm whale ( Kogia sima ) that stranded on O‘ahu in 2000, predating the initial case of BWCV. The results broaden the known geographic range of BWCV to Saipan in the Western Pacific, and American Samoa in the South Pacific, where stranded Cuvier’s beaked whales ( Ziphius cavirostris ) tested positive. Although the clinical significance is currently unknown, this study demonstrates that BWCV has a high prevalence within targeted cetacean screening efforts. Infectious diseases pose a major threat to cetaceans and BWCV may represent an important emerging disease within populations spanning the central, Western, and South Pacific.
... C etacean morbillivirus (CeMV; family Paramyxoviridae, genus Morbillivirus) is an important cause of illness and death in cetaceans (1). The genus Morbillivirus comprises 2 lineages: CeMV-1, which includes dolphin morbillivirus (DMV), porpoise morbillivirus (PMV), pilot whale morbillivirus (PWMV), and beaked whale morbillivirus (BWMV) strains; and CeMV-2, comprising the strain detected in Indo-Pacific bottlenose dolphins (Tursiops aduncus) in western Australia, the Fraser's dolphin morbillivirus (FDMV), and Guiana dolphin morbillivirus (GDMV) strains (1,2). GDMV has been the only strain reported in cetaceans in Brazil (3). ...
... M ycolicibacterium iranicum is a rapidly growing mycobacterium (RGM) and emerging cause of respiratory, wound, blood, and central nervous system infections (1,2). Phylogenetic analyses have shown that M. iranicum is more closely related to environmental mycobacterial species than pathogenic species (3), and most outbreaks have been associated with exposure to contaminated water (4,5). ...
Cetacean morbillivirus (CeMV) causes illness and death in cetaceans worldwide; the CeMV strains circulating in the Southern Hemisphere are poorly known. We detected a pilot whale CeMV strain in 3 short-finned pilot whales (Globicephala macrorhynchus) stranded in Brazil during July-October 2020. Our results confirm this virus circulates in this species.
... A member of the genus Morbillivirus (family Paramyxoviridae, subfamily Orthoparamyxovirinae), CeMV is the natural agent with the greatest impact on cetacean health and conservation worldwide [4]. This non-segmented single-stranded RNA virus includes three well-characterized strains: dolphin morbillivirus (DMV), porpoise morbillivirus, and pilot whale morbillivirus, plus four more strains recently identified in Hawaii and the southern hemisphere [5][6][7][8]. ...
... Lesions in other anatomical regions included: diffuse non-suppurative meningoencephalitis in all sections examined, along with the cerebellar and the cerebral cortex, in 8 animals (ID 1 ,6 ,14, 16, 17, 21, 23, 28), non-suppurative plexus choroiditis (Figure 2G) in 6 animals (ID 1, 4, 11, 14, 19, 24), non-suppurative myelitis in 2 animals (ID 3 and 17), oedema (Figure 2C) in 3 animals (ID 8, 16, 22). Associated lesions comprised syncytia (Figure 2D) in 11 animals (ID 1,2,7,8,14,16,19,21,23,24,27), protozoan tissue cysts associated with granulomatous encephalitis (Figure 2H) in 4 animals (ID14,16,24,26), protozoan tissue cysts alone in 1 animal (ID 1), Purkinje cell loss in 2 animals (ID 10 and 24), vasculitis in 2 animals (ID 19 and 21), suppurative and pyogranulomatous encephalitis in 1 animal each (ID 12 and 19, respectively). Three animals ...
... Lesions in other anatomical regions included: diffuse non-suppurative meningoencephalitis in all sections examined, along with the cerebellar and the cerebral cortex, in 8 animals (ID 1, 6, 14, 16, 17, 21, 23, 28), non-suppurative plexus choroiditis (Figure 2G) in 6 animals (ID 1, 4, 11, 14, 19, 24), non-suppurative myelitis in 2 animals (ID 3 and 17), oedema (Figure 2C) in 3 animals (ID 8, 16, 22). Associated lesions comprised syncytia (Figure 2D) in 11 animals (ID 1,2,7,8,14,16,19,21,23,24,27), protozoan tissue cysts associated with granulomatous encephalitis (Figure 2H) in 4 animals (ID14,16,24,26), protozoan tissue cysts alone in 1 animal (ID 1), Purkinje cell loss in 2 animals (ID 10 and 24), vasculitis in 2 animals (ID 19 and 21), suppurative and pyogranulomatous encephalitis in 1 animal each (ID 12 and 19, respectively). Three animals(ID 5,20,29) presented no protozoan cysts, although molecular analysis indicated co-infection with the parasite. ...
Cetacean morbillivirus (CeMV) is responsible for epidemic and endemic fatalities in free-ranging cetaceans. Neuro-inflammation sustained by CeMV is a leading cause of death in stranded cetaceans. A novel dolphin morbillivirus (DMV) strain of Atlantic origin circulating in Italian waters since early 2016 has caused acute/subacute lesions associated with positive immunolabelling of the virus. To date, myelin damage has not been fully documented and investigated in cetaceans. This study describes neuropathological findings in the brain tissue of 31 cetaceans found stranded along the Italian coastline and positive for DMV infection on molecular testing. Cell changes in the areas of myelinopathy were revealed by double indirect immunofluorescence. The most frequent DMV-associated lesions were astro-microgliosis, neuronal necrosis, spongiosis, malacia, and non-suppurative meningoencephalitis. Myelin reduction and areas of demyelination were revealed by means of a specific myelin biomarker. Morbilliviral antigen immunolabelling was mainly observed in neurons and microglial cells, in association with a marked activation of microglia and astrocytes. These findings extend our knowledge of DMV-associated brain lesions and shed light on their pathogenesis.
... 1 The tendency of CeMV to cross interspecies barriers was documented in recent years, showing a progressive widening of the host range and geographical distribution. [2][3][4][5] In fact, as outbreaks caused by CeMV in cetaceans from both hemispheres show, the five, hitherto recognized viral strains (termed as CeMV-1 to -5) display a high propensity for multi-host transmission and trans-oceanic spread. 6,7 CeMV infections were reported also in mammals other than cetaceans, including species with mixed aquatic-terrestrial ecology such as the common seal (Phoca vitulina), 8 the Eurasian otter (Lutra lutra), 9 and the endangered Mediterranean monk seal (Monachus monachus). ...
Cetacean morbillivirus (CeMV) infects marine mammals causing an often fatal respiratory and neurological disease. Recently, CeMV has expanded its geographic and host species range, with cases being reported worldwide among dolphins, whales, seals and other aquatic mammalian species, and therefore emerged as the most threatening non-anthropogenic factor affecting marine mammal's health and conservation. Extensive research efforts aimed to understand CeMV epidemiology and ecology, however the molecular mechanisms underlying its transmission and pathogenesis are still poorly understood. In particular, the field suffers from a knowledge gap on the structural and functional properties of CeMV proteins and their host interactors. Nevertheless, the body of scientific literature produced in recent years has inaugurated new investigational trends, driving future directions in CeMV molecular research. In this mini-review, the most recent literature has been summarized in the context of such research trends, and categorized into four priority research topics, such as i) the interaction between CeMV glycoprotein and its host cell receptors across several species; ii) the CeMV molecular determinants responsible for different disease phenotype; iii) the host molecular determinants responsible for differential susceptibility to CeMV infection; iv) the CeMV molecular determinants responsible for difference virulence among circulating CeMV strains. Arguably, these are the most urgent topics that need to be investigated and that most promisingly will help to shed light on the details of CeMV evolutionary dynamics in the immediate future.
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Cetacean morbillivirus (CeMV) has caused several outbreaks, unusual mortality events, and interepidemic single-lethal disease episodes in the Mediterranean Sea. Since 2012, a new strain with a northeast (NE) Atlantic origin has been circulating among Mediterranean cetaceans, causing numerous deaths. The objective of this study was to determine the prevalence of CeMV in cetaceans stranded in Italy between 2018 and 2021 and characterize the strain of CeMV circulating. Out of the 354 stranded cetaceans along the Italian coastlines, 113 were CeMV-positive. This prevalence (31.9%) is one of the highest reported without an associated outbreak. All marine sectors along the Italian coastlines, except for the northern Adriatic coast, reported a positive molecular diagnosis of CeMV. In one-third of the CeMV-positive cetaceans submitted to a histological evaluation, a chronic form of the infection (detectable viral antigen, the absence of associated lesions, and concomitant coinfections) was suspected. Tissues from 24 animals were used to characterize the strain, obtaining 57 sequences from phosphoprotein, nucleocapsid, and fusion protein genes, which were submitted to GenBank. Our sequences showed the highest identity with NE-Atlantic strain sequences, and in the phylogenetic study, they clustered together with them. Regarding age and species, most of these individuals were adults (17/24, 70.83%) and striped dolphins (19/24, 79.16%). This study improves our understanding on the NE-Atlantic CeMV strain in the Italian waters, supporting the hypothesis of an endemic circulation of the virus in this area; however, additional studies are necessary to deeply comprehend the epidemiology of this strain in the Mediterranean Sea.
Toxoplasma gondii is a significant threat to endangered Hawaiian wildlife including birds and marine mammals. To estimate the prevalence of T. gondii in stranded cetaceans from 1997 to 2021 in Hawai‘i, we tested tissues from 37 stranded spinner dolphins Stenella longirostris and 51 stranded individuals that represented 18 other cetacean species. DNA from cetacean tissue extracts were screened using a nested polymerase chain reaction (PCR) assay targeting the Toxoplasmatinae internal transcribed spacer 1 of the nuclear ribosomal DNA. A positive result was obtained in 9 tissues examined for each of 2 spinner dolphins out of 525 tissue samples analyzed by PCR. The PCR-positive spinner dolphins had disseminated acute toxoplasmosis with necrosis, inflammation, and intralesional protozoal cysts and tachyzoites in multiple organs. Discrete positive immunostaining for T. gondii was observed in all tissues tested including the adrenal gland, brain, liver, and lung. Both positive spinner dolphins were negative for cetacean morbillivirus. The T. gondii genotyping was performed by restriction fragment length polymorphism (PCR-RFLP) based on 10 genetic markers. The PCR-RFLP analysis revealed the T. gondii belonged to PCR-RFLP-ToxoDB genotype #24, previously detected in wild pig Sus scrofa in O‘ahu, bobcats Lynx rufus from Mississippi, USA, and chickens Gallus gallus from Costa Rica and Brazil. These cases represent the first report of this genotype in aquatic mammals and the second and third reports of fatal disseminated T. gondii infection in stranded spinner dolphins from Hawai‘i. Nearshore species, like spinner dolphins, may be at increased risk of mortality from this parasite in marine coastal waterways via sewage systems, storm water drainage, and freshwater runoff.
Currently, seven species of morbillivirus have been classified. Six of these species (Measles morbillivirus, Rinderpest morbillivirus, Small ruminant morbillivirus, Canine morbillivirus, Phocine morbillivirus, and Cetacean morbillivirus) are highly infectious and cause serious systemic diseases in humans, livestock, domestic dogs, and wild animals. These species commonly use the host proteins signaling lymphocytic activation molecule (SLAM) and nectin‐4 as receptors, and this usage contributes to their virulence. The seventh species (Feline morbillivirus: FeMV) is phylogenetically divergent from the six SLAM‐using species. FeMV differs from the SLAM‐using morbillivirus group in pathogenicity and infectivity, and is speculated to use non‐SLAM receptors. Recently, novel species of morbilliviruses have been discovered in bats, rodents, and domestic pigs. Because the ability to use SLAM and nectin‐4 is closely related to the infectivity and pathogenicity of morbilliviruses, investigation of the potential usage of these receptors is useful for estimating infectivity and pathogenicity. The SLAM‐binding sites in the receptor‐binding protein show high similarity among the SLAM‐using morbilliviruses. This feature may help to estimate whether novel morbillivirus species can use SLAM as a receptor. A novel morbillivirus species isolated from wild mice diverged from the classified morbilliviruses in the phylogenetic tree, forming a third group separate from the SLAM‐using morbillivirus group and FeMV. This suggests that the novel rodent morbillivirus may exhibit a different risk from the SLAM‐using morbillivirus group, and analyses of its viral pathogenicity and infectivity toward humans are warranted. This article is protected by copyright. All rights reserved.
A retrospective survey for detecting the cetacean morbillivirus (CeMV) was carried out in beaked whales (BWs) stranded in the Canary Islands (1999–2017). CeMV is responsible for causing worldwide epizootic events with the highest mass die-offs in cetaceans, although the epidemic status of the Canarian Archipelago seems to be that of an endemic situation. A total of 319 tissue samples from 55 BWs (35 Cuvier’s BWs and 20 specimens belonging to the Mesoplodon genus) were subjected to the amplification of a fragment of the fusion protein (F) and/or phosphoprotein (P) genes of CeMV by means of one or more of three polymerase chain reactions (PCR). RNA integrity could not be demonstrated in samples from 11 animals. Positivity (dolphin morbillivirus strain (DMV)) was detected in the skin sample of only a subadult male Cuvier’s BW stranded in 2002, being the earliest confirmed occurrence of DMV in the Cuvier’s BW species. The obtained P gene sequence showed the closest relationship with other DMVs detected in a striped dolphin stranded in the Canary Islands in the same year. A phylogenetic analysis supports a previous hypothesis of a cross-species infection and the existence of the circulation of endemic DMV strains in the Atlantic Ocean similar to those later detected in the North-East Atlantic, the Mediterranean Sea and the South-West Pacific.
