Analysis of host- and strain-dependent cell death responses during infectious salmon anemia virus infection in vitro

Berit L Schiøtz,Tor Gjøen,Lene C Poulsen,Siri Mjaaland,Espen S Bækkevold

doi:10.1186/1743-422x-6-91

Abstract

BackgroundInfectious salmon anemia virus (ISAV) is an aquatic orthomyxovirus and the causative agent of infectious salmon anemia (ISA), a disease of great importance in the Atlantic salmon farming industry. In vitro, ISAV infection causes cytophatic effect (CPE) in cell lines from Atlantic salmon, leading to rounding and finally detachment of the cells from the substratum. In this study, we investigated the mode of cell death during in vitro ISAV infection in different Atlantic salmon cell lines, using four ISAV strains causing different mortality in vivo.ResultsThe results show that caspase 3/7 activity increased during the course of infection in ASK and SHK-1 cells, infected cells showed increased surface expression of phosphatidylserine and increased PI uptake, compared to mock infected cells; and morphological alterations of the mitochondria were observed. Expression analysis of immune relevant genes revealed no correlation between in vivo mortality and expression, but good correlation in expression of interferon genes.ConclusionResults from this study indicate that there is both strain and cell type dependent differences in the virus-host interaction during ISAV infection. This is important to bear in mind when extrapolating in vitro findings to the in vivo situation.

Highlights

Infectious salmon anemia virus (ISAV) is an aquatic orthomyxovirus and the causative agent of infectious salmon anemia (ISA), a disease of great importance in the Atlantic salmon farming industry
ISAV infected cells were stained with mitotracker
We found that genes in the antioxidantresponsive element pathway regulated by Nrf2 were significantly activated by ISAV infection in vitro [31]

Summary

Introduction

Infectious salmon anemia virus (ISAV) is an aquatic orthomyxovirus and the causative agent of infectious salmon anemia (ISA), a disease of great importance in the Atlantic salmon farming industry. We investigated the mode of cell death during in vitro ISAV infection in different Atlantic salmon cell lines, using four ISAV strains causing different mortality in vivo. ISAV is the causative agent of infectious salmon anemia (ISA), an emerging disease causing high mortalities and great economic losses in the Atlantic salmon (Salmo salar L.) farming industry. Several strains of ISAV are known and categorized according to the highly polymorphic region of the hemagglutinin-esterase protein, and according to the ability of the virus to induce acute versus protracted disease in affected fish. Much is known about the structure and genetics of the virus, less is known about the immune reactions (page number not for citation purposes)

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