Atlantic salmon papillomatosis in Russia and molecular characterization of the associated herpesvirus

Abstract

Papillomatosis of Atlantic salmon Salmo salar has been reported for decades in Russia, Scandinavia and Scotland. The disease is typically benign although heavy losses have occasionally been reported. A herpesviral etiology has been suggested based on ultrastructural evidence; however, the virus has not been isolated or genetically characterized. In this study, we provide the first viral sequences detected in the papillomas from diseased Russian Atlantic salmon. Phylogenetic analyses, based on the partial sequences of the herpesviral polymerase and terminase genes, supported the virus as a novel member of the genus Salmonivirus within the family Alloherpesviridae. The sequences of the Atlantic salmon papillomatosis virus differ markedly from those of the 3 known salmoniviruses; therefore, the authors propose the species designation Salmonid herpesvirus 4 to be considered for approval by the International Committee on Taxonomy of Viruses. KEY WORDS: Atlantic salmon papillomatosis · lloherpesviridae · Salmonivirus · Fish herpesvirus · PCRResale or republication not permitted without written consent of the publisher

Initial Detection and Molecular Characterization of Namaycush Herpesvirus (Salmonid Herpesvirus 5) in Lake Trout

“…The adopted proposal to erect the genus Salmonivirus is further supported by NamHV's distinct grouping with four previously characterized salmonid herpesviruses (salmonid herpesvirus 1, 2, 3, and 4; Waltzek et al 2009). All three phylogenetic trees were similar to the previously published Alloherpesviridae phylogenetic analysis in the grouping of genera (Waltzek et al 2009;Doszpoly et al 2013). Phylogenetic trees assigned viruses from cyprinid, anguillid, and ranid hosts to clade 1, while those from salmonid, ictalurid, and acipenserid hosts represented clade 2.…”

“…Phylogenetic trees assigned viruses from cyprinid, anguillid, and ranid hosts to clade 1, while those from salmonid, ictalurid, and acipenserid hosts represented clade 2. These same assignments were reported by Doszpoly et al (2013), who used concatenated amino acid sequences of Alloherpesviridae terminase and polymerase genes (142 aa) with Bayesian analysis. One caveat pertaining to the current study was that the supporting bootstrap value at the base of clade 1 was below a 70% cutoff, thus failing to substantiate The trees were constructed with amino acid sequences of equal length by the neighbor-joining method in MEGA 3.1 (1,000 bootstrap replications, Poisson correction).…”

“…To our knowledge, ASPV, as molecularly classified by Doszpoly et al (2013), has not been described in the United States and has yet to be isolated from Lake Trout. According to Wolf (1988), a papilloma condition has been infrequently observed in young salmon in North America, but no reports in the literature indicate its molecular identity or relationship to the ASPV found in Europe.…”

“…Phylogenetic analysis by Doszpoly et al (2013) indicated that ASPV is a sister species of EEDV. However, the results from the current study indicate that NamHV shares greater nucleotide identity in the three genes studied to ASPV, thus potentially forming a sister clade.…”

“…Recently, Atlantic Salmon papillomatosis virus (ASPV), salmonid herpesvirus 4, was molecularly characterized and proposed as a fourth member of the genus Salmonivirus (Doszpoly et al 2013). Salmonid herpesvirus 4 is usually considered chronic and benign; however, varying levels of mortality have been observed and are usually associated with secondary fungal and bacterial infections (Carlisle and Roberts 1977;Wolf 1988).…”