Proteins encoded by the PRV genome and functional properties as predicted from comparative studies with selected reovirus prototype strains.

a<p>L1-M3 PRV gene segments are annotated according to mammalian reoviruses (MRV). PRV L1 has been changed to L3, and vice versa, compared to that suggested by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070075#pone.0070075-Palacios1" target="_blank">[1]</a>. PRV S-class gene segments are annotated according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070075#pone.0070075-Palacios1" target="_blank">[1]</a>. For mammalian reovirus (MRV), avian orthoreovirus (ARV) and grass carp reovirus (GCRV) several proteins are produced from alternative reading frames or by post-translational proteolytic cleavage. In the latter case, if the exact cleavage site is known, the lengths of both proteolytic fragments are included in the table.</p>b<p>T3D = Type 3 Dearing strain.</p>c<p>GCRV contains an eleventh genomic segment which encodes a non-structural protein, NS26. VP7 is homologues to σ3/σB.</p>d<p>Cytotoxic, nonfusogenic integral membrane protein <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070075#pone.0070075-Key1" target="_blank">[96]</a>.</p

The PRV genome.

<p>Gene segments are assigned according to mammalian reoviruses. Open reading frames (ORFs) and putative encoded proteins are indicated by regions in grey, with start and end positions indicated. Non-translated regions (UTR’s) at gene segment ends are shown in black. Gene segments L2, S1 and S2 are possibly polycistronic.</p

Percentage amino acid identity among all ungapped positions between pairs; predicted PRV proteins and the homologues proteins from three reovirus prototype strains.

a,b,c<p>Ref. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070075#pone-0070075-t001" target="_blank">Table 1</a> for gene segment annotations and names of homologues proteins in MRV, ARV and GCRV. Identity values are from separate pairwise alignments of the protein sequences.</p>d<p>Value from a manually adjusted pairwise alignment of the two proteins.</p>f<p>GCRV does not appear to have a cell attachment protein homologue to σ1/σC.</p

Expression and subcellular localization of the S1-encoded σ3 and p13 proteins in mammalian VERO and salmonid CHSE cells.

<p>Immunofluorescent staining of σ3 or p13 (green colour), and staining with the trans-Golgi marker WGA (red colour). Transfected VERO cells (A) and CHSE cells (B) expressing both σ3 and p13 from the large S1 ORF (upper panels), and p13 expression from the S1 internal ORF (lower panels). Nuclei are stained with DAPI (blue colour). Yellow colour indicates colocalization of p13 and WGA. Non-transfected cells stained with WGA and anti-p13 serum was used as controls (CTRL).</p

Multiple sequence alignment of PRV σ1 with MRV T3D σ1.

<p>Black lines represent putative nuclear export signals (NEP) in MRV and PRV, respectively, as predicted by NetNes 1.1. ▪ = L₁₄₉ in the MRV protein involved in a second predicted NES. ▴ = residues in the MRV protein involved in binding to sialic acid residues. The alignment has been manually adjusted.</p

DataSheet_1_Experimental transmission of piscine orthoreovirus-1 (PRV-1) in different life stages of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta).docx

Piscine orthoreovirus -1 (PRV-1) causes the disease heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon, and the virus has been detected in wild anadromous Atlantic salmon and brown trout. However, the infection prevalence, viral kinetics, and disease severity in different life stages of Atlantic salmon and brown trout are unknown. The current study aimed to evaluate and compare susceptibility to PRV-1 infection and development of HSMI in different life stages of anadromous Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). We challenged Atlantic salmon and brown trout fry, parr, and post-smolts with PRV-1 by bath, cohabitation, or IP injection. The kinetics of viral infection and disease development were evaluated by RT-qPCR, in situ hybridization, and histology. Our results indicated that PRV-1 infection prevalence and viral kinetics depend on the developmental stage and challenge method in both Atlantic salmon and brown trout. All developmental stages of Atlantic salmon and brown trout can be infected with PRV-1. However, brown trout showed a lower infection prevalence, with positive cases exhibiting only mild infections without any pathological changes in the target organs, while all life stages of Atlantic salmon developed heart lesions characteristic of HSMI. These results strongly suggest that brown trout are less susceptible to PRV-1 infection than Atlantic salmon and further confirm the species-specific susceptibility and disease development for PRV-1 infection.</p