Cetacean morbillivirus in South Atlantic Ocean
José Luiz Catão-DiasMuseo del Jade
Katia Regina Groch, Josué Diaz-Delgado
Two species of the genus Morbillivirus (family Paramyxoviridae, Order Mononegavirales) are known to affect aquatic animals: Phocine distemper virus (PDV) and Cetacean Morbillivirus (CeMV). PDV has been isolated from pinnipeds, and 5 strains of CeMV (porpoise morbillivirus-PMV, dolphin morbillivirus-DMV, pilot whale morbillivirus-PWMV, beaked whale morbillivirus-BWMV and Guiana dolphin morbillivirus-GDMV) have been detected in dolphins and whales. CeMV was first detected in Ireland, England, and the Netherlands in 19881990, when PMV was identified in stranded harbor porpoises (Phocoena phocoena). Since then, CeMV has been responsible for numerous outbreaks and endemic fatalities involving multiple cetacean species throughout the North Sea, Atlantic Ocean, Mediterranean Sea, Black Sea, Indian Ocean (Western Australia), and Pacific Ocean (Hawaii, Japan, and Australia). Serologic surveys indicate that morbilliviruses infect marine mammals worldwide. In South Atlantic Ocean, the first evidence of CeMV was positive CeMV-specific antibody titers in three Frasers dolphins (Lagenodelphis hosei) stranded off Brazil and Argentina in 1999. The first confirmed fatal case in South Atlantic cetaceans involved a Guiana dolphin (Sotalia guianensis) stranded in Espírito Santo, Brazil, in 2010. The first confirmed epizootics linked to CeMV occurred in 2017-2018 and claimed >250 Guiana dolphins in Rio de Janeiro, Brazil. The sequence data of a conserved fragment of the viral phosphoprotein (P) gene, suggest that GDMV is closer to the root of the CeMV clade than to that of DMV, PMV, BWMV or PWMV and might represent a new lineage of CeMV. Recent retrospective studies identified the virus in Southern right whales (Eubalaena australis) from Santa Catarina state, Brazil, indicating that CeMV can infect multiple cetacean species and might be widespread along the Brazilian coast. Because CeMV has been associated with a high morbidity and mortality in several cetacean species and populations, these findings raise concern for potential conservation implications for marine mammals in South America.