A novel adomavirus from proliferative skin lesions of a broadnose sevengill shark (Notorynchus cepedianus)

In May of 2022, an aquarium-maintained broadnose sevengill shark (Notorynchus cepedianus) developed proliferative skin lesions that prompted pathologic and molecular investigation. Histopathologic examination revealed epidermal hyperplasia consisting of proliferation of spinous epithelial cells with mild dysplasia. Metagenomic sequencing identified a novel adomavirus with an 18,834 base pair circular double-stranded DNA genome. The virus, provisionally named broadnose sevengill shark adomavirus (7AdoV), contains two bidirectionally expressed protein-coding gene sets. Genomic annotation and structural predictions of proteins were used to contextualize 7AdoV phylogenetically and functionally. Transcriptomic analysis showed that expression of the structural late gene set was higher than the replicative early gene set at the time of diagnostic sampling. In situ hybridization using RNAscope technology localized transcripts of the adomavirus Wasp gene to epithelial cells of the hyperplastic epidermis. Infection by this novel adomavirus was associated with superficial and proliferative lesions that were self-limiting and resolved in this shark.