Experimental susceptibility of turbot Scophthalmus maximus to viral haemorrhagic septicaemia virus isolated from cultivated turbot

The nucleotide sequences of a specific region of the glycoprotein gene were compared among 63 strains of viral haemorrhagic septicaemia virus (VHSV) isolated from fish in France between 1971 and 1999. The analysis was performed on a region corresponding to amino acids 238 to 331 of the glycoprotein gene, also designated the V2 region and previously shown to accumulate most of the mutations. The sequences of many VHSV isolates were found to be identical or very conserved. An isolate, designated L59X, obtained from elver in the Loire estuary, depicted a higher degree of divergence compared to the other French isolates. The deduced amino-acid sequences were analysed together with the results of neutralisation tests performed using monoclonal antibody 168m4 specific to serotype 1. Non-neutralised VHSV strains had mutations in the region corresponding to the previously described 168m4 epitope. Phylogenetic analysis showed that all the VHSV isolates studied, except L59X, belong to genotype I, previously described as containing VHSV strains isolated from continental Europe. Most of the VHSV isolates studied were found to be genetically related to one of the previously described VHSV strains representative of the major serotypes. Isolate L59X, which was the only French marine strain studied, was found to belong to genotype II, previously shown to encompass the VHSV strains isolated from the British Isles coastal waters. Overall there was a good correlation between the geographical origin of the studied isolates and their genetic characteristics. KEY WORDS: Viral haemorragic septicaemia virus · Novirhabdoviruses · Phylogeny · Glycoprotein Resale or republication not permitted without written consent of the publisherDis Aquat Org 52: [29][30][31][32][33][34][35][36][37] 2002 cases in sea water-reared rainbow trout had been reported (Castric & de Kinkelin 1980, Horlyck et al. 1984. However, in both these outbreaks, infected fish originated from inland VHS-infected areas. Similarly, VHSV of freshwater origin (isolate 07-71) has also been experimentally demonstrated to infect 2 marine fish species, sea bass Dicentrarchus labrax and turbot Scophthalmus maximus, following water-borne infection (Castric & de Kinkelin 1984).The accepted epidemiology of VHS changed in 1987, after it was established (Jørgensen & Olesen 1987) that a rhabdovirus isolated from cod Gadus morhua in the Baltic Sea, 8 yr before (Jensen et al. 1979), was indistinguishable from VHSV. Since then, VHSV has been recovered from several fish species caught in Pacific North Western coastal areas of the United States of America, and the North Atlantic and related sea areas (Castric et al. 1992, Ross et al. 1994, Meyers & Winton 1995, Mortensen et al. 1999.Studies of the sequence variations of the glycoprotein (G) gene of VHSV made it possible to delineate 3 different lineages designated genotypes I, II and III for continental European virus, turbot virus (North Atlantic) and Pacific virus respectively (Benmansour et al. 1997). Another study, complete...

Section: Discussionsupporting

confidence: 83%

supporting

confidence: 83%

Phylogenetic analysis of viral haemorrhagic septicaemia virus (VHSV) isolates from France (1971-1999)

Thiéry¹,

Boisséson²,

Jeffroy³

et al. 2002

“…Atlantic salmon parr (mean weight 27.5 g) and Atlantic salmon post-smolts (mean weight 273 g) were reared at the FRS Marine Research Unit, Aultbea, Ross-shire, Scotland. Before the infection experiments fish were screened for the presence of ISAV, viral haemorrhagic septicaemia virus, infectious haematopoietic necrosis virus and infectious pancreatic necrosis virus by standard virology tissue culture methods as previously described (Dannevig et al 1995, Snow & Smail 1999 and, for ISAV, by reverse transcription polymerase chain reaction (RT-PCR) (Mjaaland et al 1997).…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Experimental infection models and susceptibility of Atlantic salmon Salmo salar to a Scottish isolate of infectious salmon anaemia virus

Raynard

Snow²,

Bruno³

2001

Self Cite

Infection models for both fresh and seawater salmon were established using a Scottish isolate of infectious salmon anaemia virus (ISAV). Modes of infection were intra-peritoneal injection, cohabitation and immersion exposure, and a range of doses was tested. Development of these models using a Scottish isolate of ISAV provided an approximation of the minimum infective dose leading to mortality under different infection regimens. The models also allow prediction of the time to first mortality and an estimation of expected total mortality following the various routes of infection. Such knowledge is important to the development of anti-ISAV vaccines and to future studies aimed at understanding the biology of ISAV in general. KEY WORDS: Infectious salmon anaemia virus · Atlantic salmon · Salmo salar · Experimental infection Resale or republication not permitted without written consent of the publisherDis Aquat Org 47: [169][170][171][172][173][174] 2001 MATERIALS AND METHODS Cell culture and virus propagation. The isolate of ISAV used in this study was 0390/98, which originated from a clinical outbreak of ISAV on a salmon farm in west Scotland. The salmon head kidney-1 (SHK-1) cell line was used to propagate virus for transmission experiments according to previously described methods (Dannevig et al. 1995). Harvested virus was stored at -80°C following 2 passages in SHK-1 cells. A single aliquot of virus was titrated using the tissue culture infectious dose method (TCID 50 ) (Reed & Muench 1938, Burleson et al. 1992) following a single freezethaw cycle.Pathogen-free fish. Atlantic salmon parr (mean weight 27.5 g) and Atlantic salmon post-smolts (mean weight 273 g) were reared at the FRS Marine Research Unit, Aultbea, Ross-shire, Scotland. Before the infection experiments fish were screened for the presence of ISAV, viral haemorrhagic septicaemia virus, infectious haematopoietic necrosis virus and infectious pancreatic necrosis virus by standard virology tissue culture methods as previously described (Dannevig et al. 1995, Snow & Smail 1999 and, for ISAV, by reverse transcription polymerase chain reaction (RT-PCR) (Mjaaland et al. 1997).Experimental infection with ISAV. Fish were allowed to acclimate for 7 d and starved for 24 h before all experimental infections. Water temperatures were maintained at 10°C for the duration of each experimental infection. Freshwater was supplied from Aberdeen city drinking water, which originates from the River Dee and passes through an activated carbon filter and UV treatment before entering fish tanks. Seawater was extracted from the North Sea at a salinity of 32 ‰ and passed through a sand filter and UV disinfection treatment before entering fish tanks.Experimental infection of freshwater Atlantic salmon parr with ISAV. Atlantic salmon parr were stocked in 30 l aquaria supplied with flow rates of 40 l h -1 freshwater, at a density of 15 fish per tank. Experimental infections were obtained via immersion, i.p. and cohabitation routes. Fish were anaethetised before i.p. i...

“…Methods. Cell culture and virus propagation: The epithelioma papulosum cyprini (EPC) cell line (Fijan et al 1983) was used for the isolation, propagation and identification of virus in this study according to previously described methods (Snow & Smail 1999). The isolate of VHSV used in this study was recovered in 1995 from wild cod caught in the North Sea (H16/7/95; Smail 2000).…”

mentioning

confidence: 99%

“…Rainbow trout (mean weight 9.1 g) were produced at the FRS Experimental Fish Production Unit, Aultbea, Wester-Ross, Scotland and used as the reference susceptible fish species (de Kinkelin et al 1979, de Kinkelin & Castric 1982. Prior to infection, 10 fish were sacrificed and the organs (kidney, liver and spleen) of individual fish removed and screened for the presence of VHSV, infectious pancreatic necrosis virus (IPNV) and infectious naematopoietic necrosis virus (IHNV) as previously described (Snow & Smail 1999).…”

mentioning

confidence: 99%

Susceptibility of juvenile Atlantic cod Gadus morhua to viral haemorrhagic septicaemia virus isolated from wild-caught Atlantic cod

Snow

Cunningham²,

Bricknell³

2000

Self Cite

A European strain of viral haemorrhagic septicaemia virus (VHSV) isolated from wild-caught cod Gadus morhua (H16/7/95) was shown to cause clinical dlsease and mortality in excess of 80% in juvenile Atlantic cod when administered by the intra-peritonea1 (i.p.) route. No virus was recovered from cod cohabiting with experimentally infected fish at a ratio of 1:1, and no VHSV-associated mortality was demonstrated following immersion infection. External signs of disease in cod were the presence of exophthalmia and ascites. Virus was identified as VHSV by enzyme-linked irnmunosorbent assay (ELISA) and was recovered from both brain and organ pools (kidney, liver and spleen) of 100% of i.p. infected cod mortalities. Virus was also detected using an indirect irnmunofluorescence test on tissue imprints of kidney, liver, spleen and brain taken from moribund fish. The fact that cod were not susceptible to VHSV following waterborne exposure raises important questions surrounding the propagation, maintenance and impact of a naturally occurring reservoir of virus in the marine environment KEY WORDS: Viral haemorrhaqc septicaenua virus . VHSV .