Role of the IFN I system against the VHSV infection in juvenile Senegalese sole (Solea senegalensis)

Abstract

Senegalese sole is susceptible to marine VHSV isolates but is not affected by freshwater isolates, which may indicate differences regarding virus-host immune system interaction. IFN I induces an antiviral state in fish, stimulating the expression of genes encoding antiviral proteins (ISG). In this study, the stimulation of the Senegalese sole IFN I by VHSV infections has been evaluated by the relative quantification of the transcription of several ISG (Mx, Isg15 and Pkr) after inoculation with marine (pathogenic) and freshwater (non-pathogenic) VHSV isolates. Compared to marine VHSV, lower levels of RNA of the freshwater VHSV induced transcription of ISG to similar levels, with the Isg15 showing the highest fold induction. The protective role of the IFN I system was evaluated in poly I:C-inoculated animals subsequently challenged with VHSV isolates. The cumulative mortality caused by the marine isolate in the control group was 68%, whereas in the poly I:C-stimulated group was 5%. The freshwater VHSV isolate did not cause any mortality. Furthermore, viral RNA fold change and viral titers were lower in animals from the poly I:C + VHSV groups than in the controls. The implication of the IFN I system in the protection observed was confirmed by the transcription of the ISG in animals from the poly I:C + VHSV groups. However, the marine VHSV isolate exerts a negative effect on the ISG transcription at 3 and 6 h post-inoculation (hpi), which is not observed for the freshwater isolate. This difference might be partly responsible for the virulence shown by the marine isolate.

Immune Response of Senegalese Sole against Betanodavirus Mutants with Modified Virulence

“…This result suggests that a low amount of r3073 RNA is enough to induce an efficient immune response in fish. Similar results have been previously reported for the infection of sole with a nonpathogenic viral haemorrhagic septicaemia virus (VHSV) isolated to this fish species [32]. Regarding the replication of r3093, a 24 h lag was observed compared to wt160 replication.…”

Identification of an interferon-stimulated gene, isg15 , involved in host immune defense against viral infections in gilthead seabream ( Sparus aurata L.)

“…Poly I:C triggered an earlier and stronger up-regulation than that of both viruses, probably due to the direct activation of the immune system by poly I:C. In contrast, viruses have to replicate before they can generate a noticeable response. Similar results have been obtained for other fish isg15, both in vivo and in vitro [10,11,13,[42][43][44]49,50]; however, grouper (Epinephelus coioides) isg15 showed stronger induction after GNNV infection than after treatment with poly I:C [13].…”

In vivo study of viral haemorrhagic septicaemia virus and infectious pancreatic necrosis virus coexistence in Senegalese sole (Solea senegalensis)

“…A rapid signalling pathway induces the transcription of numerous interferon‐stimulated genes (ISG), but only a few ISG (Mx, ISG15 and PKR) have been characterized in Senegalese sole to date (Alvarez‐Torres et al . ). Mx antiviral activity has been clearly demonstrated against various RNA viruses, acting by joining nucleocapsid structures and restricting their localization within the cell (Randall & Godbourn ).…”

“…; Alvarez‐Torres et al . ). Based on these previous results, Mx will be considered as a marker of the IFN activity in this study.…”