Efficient isolation on Vero.DogSLAMtag cells and full genome characterization of Dolphin Morbillivirus (DMV) by next generation sequencing

The Dolphin Morbillivirus (DMV) genome from the frst Mediterranean epidemic (1990-’92) is the only cetacean Morbillivirus that has been completely sequenced. Here, we report the frst application of next generation sequencing (NGS) to morbillivirus infection of aquatic mammals. A viral isolate, representative of the 2006-’08 Mediterranean epidemic (DMV_IZSPLV_2008), efciently grew on Vero.DogSLAMtag cells and was submitted to whole genome characterization by NGS. The fnal genome length was 15,673 nucleotides, covering 99.82% of the DMV reference genome. Comparison of DMV_IZSPLV_2008 and 1990-’92 DMV strain sequences revealed 157 nucleotide mutations and 47 amino acid changes. The sequence similarity was 98.7% at the full genome level. Whole-genome phylogeny suggested that the DMV strain circulating during the 2006-’08 epidemics emerged from the 1990-’92 DMV strain. Viral isolation is considered the “gold standard” for morbillivirus diagnostics but efcient propagation of infectious virus is difcult to achieve. The successful cell replication of this strain allowed performing NGS directly from the viral RNA, without prior PCR amplifcation. We therefore provide to the scientifc community a second DMV genome, representative of another major outbreak. Interestingly, genome comparison revealed that the neglected L gene encompasses 74% of the genetic diversity and might serve as “hypervariable” target for strain characterization.