title: Genetic characterization of esocid herpesvirus 1 (EsHV1).
abstract: Blue spot disease, believed to be caused by esocid herpesvirus 1 (EsHV1), has been observed in wild northern pike Esox lucius in a number of cold-water locations, including the northern USA, Canada, and Ireland. In the spring of 2014, a northern pike was caught in Wisconsin displaying the characteristic bluish-white circular plaques on the dorsum and fins. Microscopic examination of hematoxylin and eosin-stained sections of the proliferative cutaneous lesions revealed a focally extensive abundance of panepidermal, megalocytic keratinocytes with karyomegaly. Enlarged nuclei stained basophilic, and an abundance of coarse eosinophilic granules were observed in the expanded cytoplasm. Transmission electron microscopy revealed aggregates of enveloped virus particles with electron-dense, hexagonal nucleocapsids surrounded by a uniformly staining ellipsoidal tegument layer within cytoplasmic vacuoles of megalocytic epidermal cells. More than 7000 bp of the EsHV1 genome were sequenced from infected skin tissues. Phylogenetic and phenetic analyses, based on the partial DNA-dependent DNA polymerase and terminase gene sequences, revealed EsHV1 forms a novel branch within the family Alloherpesviridae as the sister group to the clade that includes members of the genera Ictalurivirus and Salmonivirus. The gross, microscopic, and ultrastructural lesions reported in our study were identical to previous reports of blue spot disease in northern pike; however, here we provide the first molecular evidence supporting EsHV1 as a new species in the family Alloherpesviridae.
authors.affiliation: College of Agriculture and Life Science, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Jared T
authors.initials: JT
authors.lastname: Freitas
authors.forename: Kuttichantran
authors.initials: K
authors.lastname: Subramaniam
authors.forename: Karen L
authors.initials: KL
authors.lastname: Kelley
authors.forename: Susan
authors.initials: S
authors.lastname: Marcquenski
authors.forename: Joseph
authors.initials: J
authors.lastname: Groff
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Waltzek
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000235:genetics; D005393:Fish Diseases / Q000821:virology*; D005399:Fishes; D016679:Genome, Viral; D006564:Herpesviridae / Q000145:classification* / Q000235:genetics* / Q000648:ultrastructure; D010802:Phylogeny
chemical_list: D004279:DNA, Viral
keywords: Alloherpesviridae; Blue spot disease; Esox lucius; Northern pike