Cetacean morbillivirus in Southern Right Whales, Brazil

Abstract

Cetacean morbillivirus (CeMV) has caused repeated epizootics and interepizootic fatalities in a variety of cetacean species worldwide. Recently, a novel CeMV strain (GD-CeMV) was linked to a mass die-off of Guiana dolphins (Sotalia guianensis) in Brazil. Southern right whales (SRWs; Eubalaena australis) migrate to the southern Brazilian coast during austral winter and spring (June through November) for breeding and calving. Because unexplained high calf mortality rates have recurrently been documented in SRWs, we hypothesized they could be infected with CeMV. We developed a novel real-time RT-PCR method based on SYBR^® GREEN for detection of CeMV and identified the virus in three out of five stranded SRWs from Santa Catarina state, Brazil. The partial sequences of the morbillivirus phosphoprotein gene suggest that the virus is similar to the GD-CeMV strain. Our results indicate CeMV can infect SRWs and should be considered in the differential aetiologic diagnosis of infectious diseases in this species. It also raises concern for potential conservation implications for this species in its main coastal breeding area off Southern Brazil.

Keywords: Eubalaena australis; Morbillivirus; SYBR green real-time RT-PCR; South Atlantic Ocean; immunohistochemistry; stranding.