Isolation of the Fathead Minnow Nidovirus from Muskellunge Experiencing Lingering Mortality

Abstract

In 2011, the Fathead Minnow nidovirus (FHMNV; Genus Bafinivirus, Family Coronaviridae, Order Nidovirales) was isolated from pond-raised juvenile Muskellunge Esox masquinongy suffering from lingering mortality at the Wild Rose Hatchery in Wild Rose, Wisconsin. Moribund Muskellunge exhibited tubular necrosis in the kidneys as well as multifocal coalescing necrotizing hepatitis. The FHMNV was also isolated from apparently healthy juvenile Muskellunge at the Wolf Lake State Fish Hatchery in Mattawan, Michigan. The identity of the two syncytia-forming viruses (designated MUS-WR and MUS-WL from Wild Rose Hatchery and Wolf Lake State Fish Hatchery, respectively) as strains of FHMNV was determined based on multiple-gene sequencing and phylogenetic analyses. The pathogenicity of the MUS-WL FHMNV strain was determined by experimentally infecting naive juvenile Muskellunge through intraperitoneal injection with two viral concentrations (63 and 6.3 × 10(3) TCID50/fish). Both doses resulted in 100% mortality in experimentally infected fish, which exhibited severely pale gills and petechial hemorrhaging in eyes, fins, and skin. Histopathological alterations in experimentally infected fish were observed mainly in the hematopoietic tissues in the form of focal areas of necrosis. Phylogenetic analysis of concatenated partial spike glycoprotein and helicase gene sequences revealed differences between the MUS-WL FHMNV, MUS-WR FHMNV, and two other FHMNV originally isolated from moribund Fathead Minnows Pimephales promelas including the index FHMNV strain (GU002364). Based on a partial helicase gene sequence, a reverse transcriptase PCR assay was developed that is specific to FHMNV. These results give evidence that the risks posed to Muskellunge by FHMNV should be taken seriously. Received May 1, 2015; accepted February 8, 2016.

Retail Baitfish in Michigan Harbor Serious Fish Viral Pathogens

“…Our findings clearly demonstrated that baitfish obtained from retail bait vendors harbor OIE‐notifiable and baitfish‐associated viruses that are not only infectious to cyprinids but also to a wide range of other fish species (Faisal et al. , ). Surprisingly, some of the infected fish exhibited pronounced external signs of disease and yet remained for sale, with the possibility of ultimately finding their way into numerous waterbodies.…”

“…The Muskellunge is one such species that is fed baitfish in hatcheries and has proven susceptible to both VHSV and FHMNV (Faisal et al. , ). As a consequence, this practice may expose a highly susceptible fish species to potentially lethal, debilitating viral infections, and widespread stocking of these fish may lead to further expansion into new geographic areas.…”

“…Indeed, Muskellunge are vulnerable to FHMNV infection and can contract the virus by cohabitation and predation on infected fish (Baird and Faisal ; Faisal et al. ). Although FHMNV has been reported in Michigan previously (Faisal et al.…”

“…Subsequent studies revealed that FHMNV could infect Muskellunge naturally (Faisal et al. ) and experimentally (Baird ), causing high morbidity and mortality. In the same context, Plumb et al.…”

Antiviral activity of K22 against members of the order Nidovirales

“…The order Nidovirales was defined by the International Committee on Taxonomy of Viruses (ICTV) at the X th International Congress of Virology in Jerusalem in 1996, and currently includes four virus families: Arteriviridae, Mesoniviridae, Roniviridae and Coronaviridae, the latter being divided into the sub-families Coronavirinae and Torovirinae. Nidoviruses infect diverse host species ranging from mammals to birds, fish, crustaceans and insects (Blanck and Ziebuhr, 2016;Faisal et al, 2016;Wernery et al, 2016;Wickramasinghe et al, 2011;Zeng et al, 2016). Despite considerable diversity in terms of genome size and virion morphology, nidoviruses have been grouped together in the same virus order based on their similar genome organization, a conserved set of domains and enzymatic functions in their replicase polyproteins, and their unique transcription strategy that results in production of a set of nested (Latin nidus; nest) subgenomic mRNAs (Gorbalenya et al, 2006).…”