Susceptibility of rainbow trout to three different genogroups of infectious pancreatic necrosis virus

Abstract

Infectious pancreatic necrosis (IPN) is a globally distributed viral disease that is highly prevalent in rainbow trout Oncorhynchus mykiss farms in Finland. Seven genogroups (1-7) of infectious pancreatic necrosis virus (IPNV) exist, of which genogroup 5 (serotype Sp) is generally considered to be the most virulent in European salmonid farming. In Finland, 3 genogroups (2, 5 and 6) have been detected. Genogroup 2 is the most widespread and to date is the only genogroup associated with clinical disease in field observations. A bath challenge model infection trial was conducted to investigate the potential pathogenicity of the existing Finnish IPNV genogroups on IPNV-negative rainbow trout fry. Three Finnish IPNV isolates, a positive control (a Norwegian genogroup 5 isolate previously associated with high virulence in Atlantic salmon Salmo salar) and a negative control were used, and mortality was recorded daily for 8 wk. The Finnish IPNV genogroup 5 isolate caused the highest cumulative mortality, and the genogroup 2 isolate also caused elevated mortalities. The genogroup 6 isolate caused only low mortality, and the positive control treatment showed negligible mortality. Fish exposed to the Finnish genogroup 2 and 5 isolates had IPN-associated lesions, while no lesions were noted in the other treatment groups. These results indicate that Finnish IPNV genogroup 5 is potentially the most virulent IPNV genogroup for Finnish rainbow trout. Interestingly, the Norwegian IPNV genogroup 5 isolate caused only a subclinical IPN infection, providing further evidence for a host species-dependent, virus isolate-related difference in virulence in IPNV genogroup 5. The results also support the continuation of legislative disease control of IPNV genogroup 5 in Finnish inland waters.

Distribution and epidemiology of the infectious pancreatic necrosis virus (IPNV) in rainbow trout (Oncorhynchus mykiss) in Peru

“…Concerning the clinical findings reported in the present study, melanosis, anal congestion, anal prolapse, and ocular hemorrhage are similar to those reported in previous studies (Evensen & Santi 2008, Smail & Munro 2012, Eriksson-Kallio et al 2020.…”

Characterization of a Novel Infectious Pancreatic Necrosis Virus (IPNV) from Genogroup 6 Identified in Sea Trout (Salmo trutta) from Lake Vänern, Sweden

“…A recent study compared the pathogenicity of several Finnish IPNV isolates in rainbow trout, including one genogroup 6 isolate [ 4 ]. Like our results, they observed a low mortality rate in rainbow trout, and thus a low pathogenicity of IPNV.…”

“…To date, seven different genogroups have been described, showing a large variability in pathogenicity, with genogroup 5 being the most virulent IPNV in all species of salmonids [ 3 ]. Comparative studies of pathogenicity are available in rainbow trout, for example, for genogroup 2, 5, and 6 [ 4 ], as well as 1, 5, and 7 [ 5 ]. In both studies, the genogroup 5 isolate caused the highest mortalities.…”

Lactococcus lactis Expressing Type I Interferon From Atlantic Salmon Enhances the Innate Antiviral Immune Response In Vivo and In Vitro

“…Interferon Ia has shown antiviral effects against IHNV ( 24 ), IPNV ( 83 ), SAV ( 101 ) and an adjuvant effect in vaccines against ISAV ( 26 ), a situation that allows us to suppose that the administration of MT006 could also have antiviral effects against SAV or act as adjuvant of ISAV vaccines in Salmo salar or other salmonids infected by these viruses, which possess a system of Interferons with a high percentage of identity (>90%) with the rIFN-Ia produced by MT006. For example, IPNV, and SAV can also infect Salmo trutta , and Oncorhynchus mykiss ( 7 , 102 – 104 ); therefore, they could constitute species in which to evaluate the antiviral effect of the administration of MT006. This implies that MT006 could be used as a broad spectrum biotherapeutic agent in salmonid aquaculture, either to induce an antiviral state, or to enhance the effect of vaccines against various bacterial or viral pathogens that affect salmon farming.…”

“…In salmonids, several viral pathogens have been identified. In Atlantic salmon, the main viral pathogens are IPNV ( 7 ) and ISAV ( 8 ), which have shown devastating effects on the Chilean salmon farming industry ( 9 ). In rainbow trout, Atlantic salmon, and other salmonids, several emerging viruses have been identified; namely, VHSV, IHNV, SAV, and PRV, which show a lower impact on production ( 2 ).…”