Application of molecular techniques to the diagnosis of cetacean morbillivirus and herpesvirus in baked whales stranded in the Canary Islands

Abstract

The aim of this study was to perform an evaluation of population health among beaked whales stranded in the Canary Islands, focused on Cetacean Morbillivirus (CeMV) and Herpesvirus (HV). A total of 54 beaked whales, stranded between 1999 and 2017, were analyzed, including 34 Cuvier’s beaked whales (Ziphius cavirostris) and 20 specimens belonging to the Mesoplodon genus. The analyzed samples included skin, lung, liver, intestine, mesenteric or mediastinal lymph node, kidney, spleen and brain. A real-time polymerase chain reaction (PCR) was carried out for CeMV, with primers designed from a partial consensus sequence of the phosphoprotein gene obtained from a dolphin morbillivirus (DMV) detected in a bottlenose dolphin (Tursiops truncatus), a pilot whale morbillivirus detected in a short-finned pilot whale (Globicephala macrorhynchus) and a CeMV detected in a guiana dolphin (Sotalia guianensis), amplifying a product of about 150 base pairs (bp). A conventional nested PCR was performed for HV, amplifying a fragment of the DNA polymerase gene of the Herpesviridae family of about 200 bp. Only 1/34 animal (2.9%) was positive for DMV in the Ziphius cavirostris group. The sequence showed a 100% homology with a sequence detected in a striped dolphin (Stenella coeruleoalba) stranded in Portugal in 2007 (GenBank Acc. No.: KP835995); and 4/34 animals (11.76%) were positive for HV, with sequences showing the highest homology with an alphaherpesvirus 1 sequence detected in a Cuvier’s beaked whale stranded in the Mediterranean in 2012 (GenBank Acc. No.: KP995682). Mesoplodon genus was not positive for CeMV, while 3/20 animals (15%) were positive for HV, with sequences showing the highest homology with an alphaherpesvirus detected in a Blainville's beaked stranded in the Canary Islands in 2004 (GenBank Acc. No.: JN863234). This study increases the knowledge about viruses affecting beaked whales, being primary pathogens causing diseases, and even death, in some cases.