Identification and characterization of a novel papillomavirus in thornback skate (Raja clavata)

Papillomaviruses are non-enveloped, double-stranded DNA viruses capable of infecting a wide range of vertebrates, from chondrichthyans to mammals. In this study, we report for the first time the identification and complete genome of a papillomavirus in the thornback skate (Raja clavata), named Raja clavata papillomavirus 1 (RclaPV1). The genomic sequence was determined using a metagenomic approach and subsequently confirmed by PCR. The RclaPV1 genome is 5,539 bp in length and displays the typical organization of papillomaviruses, encoding 4 core proteins on a single DNA strand: two early genes (E1 and E2) and two late genes (L1 and L2). Maximum likelihood phylogenetic analyses of the L1 and E1 genes indicate that RclaPV1 belongs to the Secondpapillomavirinae subfamily, clustering with fish and amphibian papillomaviruses and showing closer evolutionary relationships to amphibians than to fish.