Molecular analysis of dolphin morbillivirus: A new sensitive detection method based on nested RT-PCR.

Centelleghe C, Beffagna G, Zanetti R, Zappulli V, Di Guardo G, Mazzariol S.


Abstract: Cetacean Morbillivirus (CeMV) has been identified as the most pathogenic virus for cetaceans. Over the past three decades, this RNA virus has caused several
outbreaks of lethal disease in odontocetes and mysticetes worldwide. Isolation and identification of CeMV RNA is very challenging in whales because of the poor 
preservation status frequently shown by tissues from stranded animals. Nested reverse transcription polymerase chain reaction (nested RT-PCR) is used instead
of conventional RT-PCR when it is necessary to increase the sensitivity and the specificity of the reaction. This study describes a new nested RT-PCR technique
useful to amplify small amounts of the cDNA copy of Cetacean morbillivirus (CeMV) when it is present in scant quantity in whales' biological specimens. This
technique was used to analyze different tissues (lung, brain, spleen and other lymphoid tissues) from one under human care seal and seven cetaceans stranded
along the Italian coastline between October 2011 and September 2015. A well-characterized, 200 base pair (bp) fragment of the dolphin Morbillivirus
(DMV) haemagglutinin (H) gene, obtained by nested RT-PCR, was sequenced and used  to confirm DMV positivity in all the eight marine mammals under study. In
conclusion, this nested RT-PCR protocol can represent a sensitive detection method to identify CeMV-positive, poorly preserved tissue samples. Furthermore,
this is also a rather inexpensive molecular technique, relatively easy to apply.