Table 1.
PRV-Om challenge trials, overview of samples and analyses.
Fig 1.
Rainbow trout and Atlantic salmon short term study (Trial 1): PRV-Om in blood, histopathology and tissue distribution.
Virus analysis was performed by RT-qPCR targeting the PRV-Om segment S1 on blood from A) rainbow trout and B) Atlantic salmon. Large dots indicate Ct value of individual fish and dotted trend lines the mean Ct value of virus-positive fish. Virus-injected fish (red) and cohabitants (green) are shown. The table below the graphs shows the number of virus positive fish and examined fish per sampling point. C) Epicarditis (short arrow) and endo- and myocarditis (long arrow) in rainbow trout cohabitant # 5, 8 WPC. D) Ct values of PRV-Om RNA in organs from five individual rainbow trout cohabitants 8 WPC. The heart value of the individual with heart pathology (# 5) is marked by arrow.
Fig 2.
Rainbow trout long-term study (trial 2): PRV-Om in blood and heart.
A) Virus analysis performed by RT-qPCR targeting PRV-Om segment S1 in blood from virus-injected fish from three tanks (Tank 1: purple, parallel tanks 2 and 3: red) and cohabitants from tanks 2 and 3 (green). Large dots indicate Ct values of individual fish and dotted trend lines the mean Ct value of virus-positive fish. The table below shows number of positive fish per sampling point. B) PRV-Om Ct values in heart of fish from tanks 2 and 3. C) Detection of PRV-Om in rainbow trout red blood cells using rabbit antiserum targeting PRV-Ss σ1. Arrows mark positive staining.
Fig 3.
Rainbow trout long-term study (trial 2): Histopathological findings.
A) Prevalence of rainbow trout with heart pathology after injection of PRV-Om (red) and in cohabitants (green). Five fish were sampled from each group at each time point. The table below shows the number of positive fish out of total number examined. B–C) Light microscopic images of heart of a rainbow trout cohabitant (8 WPC). B) Epicarditis (long arrow) and perivasculitis in the compact layer of the ventricle (short arrow). C) Focal endo- and myocarditis in the spongious layer of the ventricle (arrows).
Fig 4.
Atlantic salmon long-term study (trial 3): PRV-Om in blood and heart.
A) Virus analysis performed by RT-qPCR targeting segment S1 in blood from virus-injected fish (red) and cohabitant fish (green). Large dots indicate the Ct value of individual fish and dotted trend lines the mean Ct value of virus-positive fish. The table below shows the number of positive fish per sampling point. B) PRV-Om Ct values in heart. C) Detection of PRV-Om in erythrocytes using rabbit antiserum targeting PRV σ1. Arrows point to cells with PRV-Om inclusions (green). The cell nuclei are dyed blue (Hoechst). D) Detection of dsRNA inclusions in erythrocytes in lumen of the heart ventricle using an antibody targeting dsRNA.
Fig 5.
Atlantic salmon long-term study (trial 3): Histopathological findings.
A) Prevalence of Atlantic salmon with focal myocarditis in heart ventricle of PRV-Om injected and cohabitant fish. Eight fish from each group were examined at each sampling. The table below shows the number of positive fish out of total number examined. B-C) Light microscopic images of an Atlantic salmon heart ventricle 12 weeks after injection of the virus. B) Mild focal endo- and myocarditis (arrows). C) Mild but more distinct focal myocarditis (arrows).
Fig 6.
Spleen antiviral responses to PRV-Om.
Fold increase in expression of the interferon-regulated antiviral genes Mx and viperin during the course of infection with PRV-Om in rainbow trout cohabitants (A, B) and Atlantic salmon cohabitants (C, D) from the two long-term trials (trial 2 and 3). Individual values of fold induction and bar at mean is shown. Significant differences from control fish are shown * P<0,05, *** P<0,001.