Pathogenesis of spring viremia of carp virus in emerald shiner Notropis atherinoides Rafinesque, fathead minnow Pimephales promelas Rafinesque and white sucker Catostomus commersonii (Lacepede)

Abstract

Spring viremia of carp (SVC) is a reportable disease to the World Organization of Animal Health (OIE) as it is known to cause significant international economic impact. In Canada, the first and only isolation of SVC virus (SVCV) was in 2006, from common carp Cyprinus carpio L., at Hamilton Harbour, Lake Ontario. The susceptibility of fathead minnow Pimephales promelas Rafinesque, emerald shiner Notropis atherinoides Rafinesque and white sucker Catostomus commersonii (Lacepede) to intraperitoneal injection of the Canadian isolate (HHOcarp06) was evaluated using experimental infection, virus isolation, quantitative reverse transcription polymerase chain reaction (qRT-PCR), histopathology and immunohistochemistry (IHC). Emerald shiner and fathead minnow were most susceptible with 43 and 53% cumulative mortality, respectively, compared with koi at 33%. Quantitative RT-PCR demonstrated that koi had high viral loads throughout the experiment. At 34 days post-infection, SVCV was detected from sampled emerald shiner and white sucker in very low titre and was not detected from fathead minnow. Koi, fathead minnow and emerald shiner had gross lesions typical of SVC disease. The histopathological picture was mostly dominated by necrotic changes in kidney, spleen, liver, pancreas and intestine. IHC further confirmed SVCV infection, and staining was largely correlated with histological lesions.

Spring viraemia of carp virus: recent advances

“…There are only a few reports on histological changes of SVCV-infected fish (Negele, 1977;Ghasemi et al, 2014;Misk et al, 2015). The histological changes associated with liver may range from perivasculitis to panvasculitis with a higher degree of oedematization and loss of structure of blood vessels walls (Negele, 1977).…”

“…Lymph vessels can be extremely dilated and engorged with detritus, macrophages and lymphocytes (Ahne et al, 2002). Multifocal necrosis and non-purulent inflammation often occur in the pancreas of affected fish, and the heart shows pericarditis and discontinuous myodegeneration (Negele, 1977;Misk et al, 2015). The visceral and parietal serosa of the peritoneum show peritonitis.…”

“…The renal tubuli can be obstructed by the tube casts, and may exhibit vacuolation and hyaline degeneration (Ahne et al, 2002;Misk et al, 2015). The epithelial layer of the swim bladder changes into a discontinuous multilayer and haemorrhages are commonly observed in the submucosa (Ahne et al, 2002).…”

“…Petechial haemorrhages can be seen on the skin, gills, eyes and internal organs, particularly on the walls of the swim bladder (Ahne et al, 2002;Sanders et al, 2003). Other lesions may include degeneration of the gill lamellae, oedematous internal organs, swollen and coarse-textured spleen, hepatic necrosis, enteritis, and pericarditis (Ghasemi et al, 2014;Misk et al, 2015).…”

“…Natural SVCV infections have been reported in other cyprinid fish, including goldfish (Carassius auratus), koi (Cyprinus carpio koi), silver carp (Hypophthalmichthys molitrix), crucian carp (Carassius carassius), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), tench (Tinca tinca) and orfe (Leuciscus idus) (Fijan, 1984;Shchelkunov & Shchelkunova, 1989;Ahne et al, 2002). Experimental infections have been reported in zebrafish (Danio rerio), golden shiner (Notemigonus crysoleucas), roach (Rutilus rutilus), guppy (Lebistes reticulatus), pumpkinseed (Lepsomis gibbosus), northern pike (Esox lucius), fathead minnow (Pimephales promelas), emerald shiner (Notropis atherinoides) and white sucker (Catostomus commersonii) (Ahne, 1985;Haenen & Davidse, 1993;Ahne et al, 2002;Misk et al, 2015). SVCV infection is highly lethal in young fish, with mortality rates up to 90% (Baudouy et al, 1980), and thus causes substantial economic losses to the aquaculture industry.…”