Virulence of viral hemorrhagic septicemia virus (VHSV) genotypes Ia, IVa, IVb, and IVc in five fish species

Abstract

The susceptibility of yellow perch Perca flavescens, rainbow trout Oncorhynchus mykiss, Chinook salmon O. tshawytscha, koi Cyprinus carpio koi, and Pacific herring Clupea pallasii to 4 strains of viral hemorrhagic septicemia virus (VHSV) was assessed. Fish were challenged via intraperitoneal injection with high (1 × 10 6 plaque-forming units, PFU) and low (1 × 10 3 PFU) doses of a European strain (genotype Ia), and North American strains from the West coast (genotype IVa), Great Lakes (genotype IVb), and the East coast (genotype IVc). Pacific herring were exposed to the same VHSV strains, but at a single dose of 5 × 10 3 PFU ml −1 by immersion in static seawater. Overall, yellow perch were the most susceptible, with cumulative percent mortality (CPM) ranging from 84 to 100%, and 30 to 93% in fish injected with high or low doses of virus, respectively. Rainbow trout and Chinook salmon experienced higher mortalities (47 to 98% CPM) after exposure to strain Ia than to the other virus genotypes. Pacific herring were most susceptible to strain IVa with an average CPM of 80% and moderately susceptible (42 to 52% CPM) to the other genotypes. Koi had very low susceptibility (≤5.0% CPM) to all 4 VHSV strains. Fish tested at 7 d post challenge were positive for all virus strains, with yellow perch having the highest prevalence and concentrations of virus, and koi the lowest. While genotype Ia had higher virulence in salmonid species, there was little difference in virulence or host-specificity between isolates from subtypes IVa, IVb, and IVc.

Susceptibility of goldsinny wrasse, Ctenolabrus rupestris L. (Labridae), to viral haemorrhagic septicaemia virus (VHSV) genotype III: Experimental challenge and pathology

“…To date, mortality in wild fish attributed to VHS disease is restricted to North American and Pacific Ocean isolates of genotype IV (Lumsden et al, 2007;Emmenegger et al, 2013) while wild fish sub-clinically infected with genotype III represent virus carriers and do not normally exhibit disease signs. Under aquaculture conditions, VHSV gIII was found causing disease in turbot (Scophthalmus maximus) (Ross et al, 1994) and in rainbow trout (Oncorhynchus mykiss) (Dale et al, 2009;Duesund et al, 2010).…”

“…The incoming water treatment involves sand filtration and UV disinfection to ensure a pathogen free environment. The water was maintained at 10 AE 1 C. Prior to the experimental challenges, 5 wrasse were screened by qRT-PCR for presence of infectious salmon anaemia virus (ISAV), VHSV, infectious haematopoietic necrosis virus (IHNV) and IPNV according to published methods (Snow et al, 2006;Jonstrup et al, 2013;Emmenegger et al, 2013;McBeath et al, 2007) and tested negative. Fish were fed a commercial pelleted diet (Biomar & Skretting) at 1.5% body weight per day and regularly checked four times a day.…”

Experimental infection of six North American fish species with the North Carolina strain of spring Viremia of Carp Virus

“…However, further characterization of these isolates by Betts and colleagues (2003), and recent comprehensive phylogenetic analyses (Talbi et al, 2011;Stone et al, 2013) (Kim and Faisal, 2010;Emmenegger et al, 2013) and natural epidemics due…”

“…For example, yellow perch of three different broodstocks had significant variation in mortality when challenged with VHSV- IVb (Olson et al, 2013). Similarly, using multiple virus strains/genotypes would better demonstrate if a fish species has broad susceptibility or constricted strain-specificity to a particular pathogen as shown for VHSV (Emmenegger et al, 2013) and IHNV (LaPatra et al, 1993;Garver et al, 2006;Breyta et al, 2013).…”

Viral haemorrhagic septicaemia virus (VHSV Id) infections are detected more consistently using syndromic vs. active surveillance

“…Viral haemorrhagic septicaemia (VHS) is a fish disease that has been described in more than 80 fish species in both fresh and marine waters (review by Skall et al 2005a, Elsayed et al 2006, Lumsden et al 2007, Dale et al 2009, Bain et al 2010, Gadd et al 2010, Kim & Faisal 2010, Emmenegger et al 2013, Ito & Olesen 2013). The disease is caused by VHS virus (VHSV), a virus belonging to the genus Novirhabdovirus of the family Rhabdoviridae (Walker et al 2000).…”