Characterization of a Novel Picornavirus Isolate from a Diseased European Eel ( Anguilla anguilla )

Abstract

A novel picornavirus was isolated from specimens of a diseased European eel (Anguilla anguilla). This virus induced a cytopathic effect in eel embryonic kidney cells and high mortality in a controlled transmission study using elvers. Eel picornavirus has a genome of 7,496 nucleotides that encodes a polyprotein of 2,259 amino acids. It has a typical picornavirus genome layout, but its low similarity to known viral proteins suggests a novel species in the family Picornaviridae.A ll members of the family Picornaviridae are small, nonenveloped, icosahedral viruses with positive-strand RNA genomes. Genome sizes range from 7,000 to 9,100 nucleotides. The 5= end of the RNA is covalently linked to a small virus-encoded peptide (3B); the 3= end is polyadenylated. The genome encodes one or two polyproteins that are processed co-and posttranslationally into 10 to 14 mature polypeptides. Cap-independent translation initiation is stimulated by one or two internal ribosome entry site (IRES) elements. Common to all picornaviruses are homologous capsid proteins and the nonstructural proteins 2C, 3Cpro , and 3Dpol . The sequences of other nonstructural proteins (leader protein, 2A, 2B, 3A, and 3B) are not conserved and may be unique to some picornavirus genera (1, 2).The family Picornaviridae is currently comprised of 37 species grouped into 17 genera (Aphthovirus, Aquamavirus, Avihepatovirus, Cardiovirus, Cosavirus, Dicipivirus, Enterovirus, Erbovirus, Hepatovirus, Kobuvirus, Megrivirus, Parechovirus, Salivirus, Sapelovirus, Senecavirus, Teschovirus, and Tremovirus; http: //ictvonline.org/). However, picornavirus taxonomy is still in flux, as next-generation sequencing technologies facilitate metagenomics studies using viral nucleic acid-containing specimens. Analysis of viral genomes without prior virus isolation led to the identification of more than 30 approved or tentative picornavirus species from humans (cosavirus [3] Although all published picornaviruses were identified in mammals and birds, there are reports of picornavirus-like viruses of reptiles (24, 25), fish (26-31), and marine invertebrates (32-35), indicating circulation of such viruses in aquatic ecosystems. Here, we describe a fish picornavirus which proves that picornavirus ecology indeed includes lower vertebrates of freshwater and probably marine ecosystems. Eel picornavirus 1 (EPV-1) was isolated from a European eel (Anguilla anguilla) from Lake Constance on the Rhine River. The viral genome contains an open reading frame (ORF) of 6,777 nucleotides (2,259 amino acids [aa]), and the predicted polyprotein displays the typical organization of a picornavirus. According to the Picornavirus Study Group criteria (www .picornastudygroup.com/definitions/genus_definition.htm), low similarity to the conserved P1 and 3CD precursor proteins of EPV-1 suggests a novel genus in the family Picornaviridae.Starting in May 2005, an increased number of diseased or dead eels were observed in fish traps and aquacultures in the Lake Constance area. Diseased fish presented with...

Virus isolate from carp: genetic characterization reveals a novel picornavirus with two aphthovirus 2A-like sequences

“…Recently, we completed the sequence of eel picornavirus 1 (EPV-1), which was isolated from the common eel (Fichtner et al, 2013). Here, we describe another fish picornavirus, which further substantiates the importance of limnic ecosystems for picornavirus ecology.…”

“…This indicates that the natural infection route is not an obvious one. In contrast, elvers were readily infected by swimming in eel picornavirus-containing water (Fichtner et al, 2013). Picornaviruses in terrestrial ecosystems spread by droplet infection or a faecal-oral infection route via contaminated surfaces and water.…”

A multiplex RT-PCR assay for the detection of fish picornaviruses

“…Little was known about picornaviruses in fish until recent reports of novel picornaviruses in common carp (Cyprinus carpio; Lange et al, 2014), European glass eel (Anguilla anguilla; Fichtner et al, 2013), bluegill (Lepomis macrochirus; Barbknecht et al, 2014), and fathead minnows (Pimephales promelas; Phelps et al, 2014). These viruses are herein referred to as carp picornavirus-1 (CPV-1), eel picornavirus-1 (EPV-1), bluegill picornavirus-1 (BGPV-1) and fathead minnow picornavirus (FHMPV).…”

Current Advances in Functional Genomics in Aquaculture

“…However, the upcoming of metagenomics has accelerated our discovery of novel pathogens in which the duration from observation of irst clinical signs to identiication of the etiological agent has been reduced. In ish, viruses discovered using metagenomics include circoviruses from common bream [34] and European eel [35], posavirus [36] and seadornavirus [37] from freshwater carp and totivirus from golden shiner. As shown in our recent study [9], more than 20 novel ish pathogenic viruses have been identiied using metagenomics in the last 4 years, which is more than the number identiied using traditional diagnostic tools in the last 5 decades, clearly showing the rapid rate at which metagenomics has accelerated our ability to identify novel pathogens compared with traditional diagnostic methods.…”