Susceptibility of spotted wolffish Anarhichas minor to experimental infection with nodavirus and infectious pancreatic necrosis virus

Abstract

The spotted wolffish Anarhichas minor is a promising new species for cold-water aquaculture. The broad host-range of piscine nodavirus (NV) and infectious pancreatic necrosis virus (IPNV) makes them potentially pathogenic to new fish species in aquaculture. IPNV and NV strains highly pathogenic in farmed Atlantic salmon Salmo salar and halibut Hippoglossus hippoglassus, respectively, in Norway were used for the challenge of spotted wolffish. In general, water-borne infection with IPNV and NV resulted in significant mortality among juveniles <1 g. Cumulative mortality after bath-challenge and cohabitation was 60 to 75% in the smallest juveniles (0.3 g). Intramuscular and intraperitoneal injection of NV was 100% lethal to wolffish of 10 g, and the groups at 12°C died before those at 7°C. No cohabitants of this size died, but NV was still detectable in these individuals after 10 wk. A persistent IPNV infection with low mortality developed in bath-challenged juveniles of 0.7 g, in which IPNV was still detectable 4 mo later. This study comprises a demonstration of experimental viral infections in cultured spotted wolffish, although to date no natural outbreaks of viral diseases have been reported in this species. KEY WORDS: Viral nervous necrosis · VNN · Viral encephalopathy and retinopathy · VER · Nodavirus · Infectious pancreatic necrosis · IPN · IPN virus · Spotted wolffish Resale or republication not permitted without written consent of the publisherDis Aquat Org 59: [101][102][103][104][105][106][107][108] 2004 Nakai 1997), and recently in the USA (Curtis et al. 2001) and Atlantic Canada (Johnson et al. 2002). Like IPN, VNN has caused high mortality in fry of Atlantic halibut (Grotmol et al. 1995), and in Atlantic cod (Starkey et al 2001, Johnson et al. 2002. Recently a persistent infection of NV was reported in halibut juveniles (Johansen et al 2002).The broad host-range of NV and IPNV makes these viruses potentially pathogenic to new fish species in aquaculture. The aim of the present study was to investigate the susceptibility of spotted wolffish juveniles to NV and IPNV strains highly pathogenic to farmed Atlantic salmon and halibut in Norway, and proactively study the possibility of VNN or IPN outbreak in this species. Some factors known to affect the outcome of these viral infections in fishes, such as host size, water temperature and infection route, were examined in 3 separate challenge experiments. However, the virulence of NV and IPNV was not compared. MATERIALS AND METHODSInitially, production of farmed spotted wolffish was small and limited the number of fish available for experimental studies. The present study was performed over a 4 yr period, using 3 different generations of spotted wolffish progeny (P) produced in 1998, 2000 and 2001. Attempts at viral detection were done on all batches of non-challenged wolffish: in 2 pools of 5 juveniles sampled at the start and the end of the trials, as well as in dead individuals. Due to the low number of control fish in Expt 1, these were only...

Viral encephalopathy and retinopathy (VER) in Atlantic salmon Salmo salar after intraperitoneal challenge with a nodavirus from Atlantic halibut Hippoglossus hippoglossus

“…In Atlantic halibut Hippoglossus hippoglossus of 20 g, no clinical signs of mortality were observed, but Q-PCR detection revealed an increase in virus in brain tissue post injection (Grove et al 2003). In similar studies in spotted wolffish Anarhichas minor, a nodavirus originating from Atlantic halibut caused mortality in 10 g fish after intraperitoneal and intramuscular injections as well as in 0.7 g juveniles after bath-challenge , Sommer et al 2004). However, reports on juvenile sea bream Sparus aurata suggest that there are differences in host susceptibility, as intraperitoneal injection failed to reproduce clinical signs (Aranguren et al 2002).…”

“…Resale or republication not permitted without written consent of the publisher Dis Aquat Org 68: 7-15, 2005 such as cod Gadus morhua (Starkey et al 2001, Johnson et al 2002, Gagne et al 2004, Atlantic halibut Hippoglossus hippoglossus (Grotmol et al 1995, Grotmol et al 1997b) and spotted wolffish Anarhichas minor , Sommer et al 2004. In Norway, Atlantic halibut hatcheries have suffered several outbreaks of VER during the past few years (Dannevig et al 2000, Johansen et al 2004a, suggesting the persistence of virus in cultured populations.…”

Susceptibility of Atlantic cod Gadus morhua juveniles to different routes of experimental challenge with infectious pancreatic necrosis virus (IPNV)

“…When this IPNV strain was used for challenge of smaller juveniles of spotted wolffish, titres of 10 5 to 10 8 TCID 50 g -1 tissue were registered in IPN-diseased fish after 4 wk. The infection was reported to still persist after 4 mo with titres of 10 3.5 TCID 50 g -1 tissue, demonstrating a carrier state of IPNV (Sommer et al 2004). Whether the present experimental IPNV infection in cod would have developed into a carrier state is not known.…”

“…Error bars: SEM (n = 10). *Significant differences to the calibrator (p < 0.05) generally the most susceptible to IPNV-induced mortality (Novoa et al 1993, Biering et al 1994, Sommer et al 2004), but the viral strain and water temperature also have an influence (Saint-Jean et al 2003, Santi et al 2004. The viral strain used in this experiment was originally isolated from IPN diseased halibut fry and has caused high mortality in bath-challenged spotted wolffish fry (Sommer et al 2004).…”

Horizontal transmission of nervous necrosis virus between turbot Scophthalmus maximus and Atlantic cod Gadus morhua using cohabitation challenge

“…In Norway, this virus has been detected in several fish species including farmed ones such as turbot Scophthalmus maximus (Bloch et al 1991, Johansen et al 2004, Atlantic halibut Hippoglossus hippoglossus (Grotmol et al 1995, Aspehaug et al 1999, Hellberg & Dannevig 2002, 2003 and Atlantic cod Gadus morhua (Patel et al 2007). In addition, spotted wolfish Anarhichas minor (Johansen et al 2003, Sommer et al 2004 and Atlantic salmon Salmo salar (Korsnes et al 2005) were found to be susceptible by intraperitoneal (i.p.) injection with NNV.…”