Dolphin Morbillivirus: a lethal but valuable infection model

Abstract

Dolphin Morbillivirus (DMV), which has caused at least four epidemics in the Western Mediterranean during the last 20–25 years, may dramatically impact the health and conservation of striped dolphins (Stenella coeruleoalba) living in this area. The viral and host factors driving the host–DMV interaction, along with those related to the climate change that underlie the occurrence of DMV epidemics, warrant further investigation.

Spatio-temporal patterns of genetic diversity in the Mediterranean striped dolphin (Stenella coeruleoalba)

“…The sharp increases in F IS are consistent with the two better described epizootic events (1990–1992 and 2006–2008; Van Bressem et al., ), and with a third event between 1997 and 1999 for which there is also evidence (though weaker than for the other two epizootics) from serological essays (Van Bressem et al., ). The suggested cycle of 3–5 years for morbillivirus epizootics in striped dolphin (Di Guardo & Mazzariol, ) would predict another epizootic around 2002 and 2004, but no strong genetic footprint appears evident in our genetic analyses, nor is this strongly documented in the literature. Although there is a slight increase in F IS in 2002, this is much smaller as compared to the changes observed in other better documented epizootics.…”

“…Previous studies suggest that striped dolphins in the Mediterranean basin are genetically differentiated from the Atlantic Ocean (Bourret, Macé, & Crouau‐Roy, ; Garcia‐Martinez, Moya, Raga, & Latorre, ; Gaspari et al., ), with further subdivision within the Mediterranean Sea being suggested by kinship analysis (Gaspari et al., ) and factorial analyses (Gkafas et al., ). Furthermore, in the last three decades the striped dolphin has faced ecological pressure from a series of morbillivirus epizootics across the Mediterranean basin (Di Guardo & Mazzariol, ). The earliest during 1990–1992 was particularly severe, with thousands of animals succumbing to the disease (Cebrian, ).…”

“…The earliest during 1990–1992 was particularly severe, with thousands of animals succumbing to the disease (Cebrian, ). Since then, other epizootic episodes have been described, and although the strength of supporting evidence varies, a 3 to 5 year cycle of occurrence has been suggested (Di Guardo & Mazzariol, ). Cetacean morbillivirus (CeMV) was first recognized formally about 20 years ago and is considered one of the most pathogenic virus in cetaceans (Barrett et al., ; Lipscomb et al., ; Taubenberger et al., ; Van Bressem et al., ), with large die‐offs described worldwide (Van Bressem et al., ).…”

Cetacean Morbillivirus-Associated Pathology: Knowns and Unknowns

“…Of special concern, from the comparative neuropathology and viral neuropathogenesis perspective, are the “brain-only” forms of morbilliviral infection which have been increasingly reported, after the 1990–1992 and the 2006–2008 epidemics, among CeMV-affected striped dolphins in the western Mediterranean ( Domingo et al, 1995 ; Di Guardo et al, 2011a , 2013 ; Soto et al, 2011 ), with two additional cases having been also described in a CeMV-infected bottlenose dolphin from the same area ( Di Guardo et al, 2013 ) as well as in a wild, “hospitalized” white-beaked dolphin ( Lagenorhynchus albirostris ; Van Elk et al, 2014 ) and in four striped dolphins stranded along the Canary Islands’ coasts between 2002 and 2011 ( Van Bressem et al, 2014 ). Animals suffering from this peculiar form of infection show evidence of morbilliviral genome and/or antigens exclusively in the brain, with their lesions closely resembling those found in Measles Virus (MeV)-infected, “subacute sclerosing panencephalitis” (SSPE)-affected patients ( Sato et al, 2012 ; Di Guardo and Mazzariol, 2013 ). In this respect, provided that the host- and the virus-related factors driving host-CeMV interaction are largely undefined, special emphasis should be placed upon the mechanisms underlying viral colonization and persistence within the brain of chronically infected dolphins ( Di Guardo et al, 2013 ).…”

“…Throughout the last 25–30 years, at least nine morbilliviral epidemics have affected free-ranging cetacean populations from different areas of the planet ( Van Bressem et al, 2014 ). Striped dolphins ( Stenella coeruleoalba ) have been the main “target” of the four outbreaks occurred in the western Mediterranean between 1990 and 2013, with pilot whales ( Globicephala melas ) having been also involved in the 2006–2008 epidemic in the same area ( Fernández et al, 2008 ; Raga et al, 2008 ; Di Guardo and Mazzariol, 2013 ; Casalone et al, 2014 ; Van Bressem et al, 2014 ). Bottlenose dolphins ( Tursiops truncatus ), at their time, have been the main species affected by the four outbreaks occurred, between 1982 and 2014, along the Atlantic seaboards of USA (1982, 1987–1988, 2013–2014) ( Lipscomb et al, 1994b ; Krafft et al, 1995 ; Di Guardo et al, 2005 ; Van Bressem et al, 2009 , 2014 ) and Mexico (1994) ( Lipscomb et al, 1994a , 1996 ; Krafft et al, 1995 ; Di Guardo et al, 2005 ; Van Bressem et al, 2009 ), while common dolphins ( Delphinus delphis ponticus ) were the species targeted by the 1994 epidemic in the Black Sea ( Birkun et al, 1999 ; Di Guardo et al, 2005 ; Van Bressem et al, 2009 ).…”