Dataset Information

Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells.

ABSTRACT: Piscine orthoreovirus (PRV) is ubiquitous in farmed Atlantic salmon (Salmo salar) and the cause of heart and skeletal muscle inflammation. Erythrocytes are important target cells for PRV. We have investigated the kinetics of PRV infection in salmon blood cells. The findings indicate that PRV causes an acute infection of blood cells lasting 1-2 weeks, before it subsides into persistence. A high production of viral proteins occurred initially in the acute phase which significantly correlated with antiviral gene transcription. Globular viral factories organized by the non-structural protein µNS were also observed initially, but were not evident at later stages. Interactions between µNS and the PRV structural proteins ?1, µ1, ?1 and ?3 were demonstrated. Different size variants of µNS and the outer capsid protein µ1 appeared at specific time points during infection. Maximal viral protein load was observed five weeks post cohabitant challenge and was undetectable from seven weeks post challenge. In contrast, viral RNA at a high level could be detected throughout the eight-week trial. A proteolytic cleavage fragment of the µ1 protein was the only viral protein detectable after seven weeks post challenge, indicating that this µ1 fragment may be involved in the mechanisms of persistent infection.

SUBMITTER: Haatveit HM

PROVIDER: S-EPMC5371804 | biostudies-other | 2017 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells.

Haatveit Hanne Merethe HM Wessel Øystein Ø Markussen Turhan T Lund Morten M Thiede Bernd B Nyman Ingvild Berg IB Braaen Stine S Dahle Maria Krudtaa MK Rimstad Espen E

Viruses 20170318 3

<i>Piscine orthoreovirus</i> (PRV) is ubiquitous in farmed Atlantic salmon (<i>Salmo salar</i>) and the cause of heart and skeletal muscle inflammation. Erythrocytes are important target cells for PRV. We have investigated the kinetics of PRV infection in salmon blood cells. The findings indicate that PRV causes an acute infection of blood cells lasting 1-2 weeks, before it subsides into persistence. A high production of viral proteins occurred initially in the acute phase which significantly co ...[more]

PMID: 28335455

Similar Datasets

Project description:BackgroundVertebrate hosts limit the availability of iron to microbial pathogens in order to nutritionally starve the invaders. The impact of iron deficiency induced by the iron chelator deferoxamine mesylate (DFO) was investigated in Atlantic salmon SHK-1 cells infected with the facultative intracellular bacterium Piscirickettsia salmonis.ResultsEffects of the DFO treatment and P. salmonis on SHK-1 cells were gaged by assessing cytopathic effects, bacterial load and activity, and gene expression profiles of eight immune biomarkers at 4- and 7-days post infection (dpi) in the control group, groups receiving single treatments (DFO or P. salmonis) and their combination. The chelator appears to be well-tolerated by host cells, while it had a negative impact on the number of bacterial cells and associated cytotoxicity. DFO alone had minor effects on gene expression of SHK-1 cells, including an early activation of IL-1β at 4 dpi. In contrast to few moderate changes induced by single treatments (either infection or chelator), most genes had highest upregulation in the infected groups receiving DFO. The mildest induction of hepcidin-1 (antimicrobial peptide precursor and regulator of iron homeostasis) was observed in cells exposed to DFO alone, followed by P. salmonis infected cells while the addition of DFO to infected cells further increased the mRNA abundance of this gene. Transcripts encoding TNF-α (immune signaling) and iNOS (immune effector) showed sustained increase at both time points in this group while cathelicidin-1 (immune effector) and IL-8 (immune signaling) were upregulated at 7 dpi. The stimulation of protective gene responses seen in infected cultures supplemented with DFO coincided with the reduction of bacterial load and activity (judged by the expression of P. salmonis 16S rRNA), and damage to cultured host cells.ConclusionThe absence of immune gene activation under normal iron conditions suggests modulation of host responses by P. salmonis. The negative effect of iron deficiency on bacteria likely allowed host cells to respond in a more protective manner to the infection, further decreasing its progression. Presented findings encourage in vivo exploration of iron chelators as a promising strategy against piscirickettsiosis.

Project description:Salmon Gill Poxvirus Disease (SGPVD) has emerged as a cause of acute mortality in Atlantic salmon (Salmo salar L.) presmolts in Norwegian aquaculture. The clinical phase of the disease is associated with apoptotic cell death in the gill epithelium causing acute respiratory distress, followed by proliferative changes in the regenerating gill in the period after the disease outbreak. In an experimental SGPV challenge trial published in 2020, acute disease was only seen in fish injected with hydrocortisone 24 h prior to infection. SGPV-mediated mortality in the hydrocortisone-injected group was associated with more extensive gill pathology and higher SGPV levels compared to the group infected with SGPV only. In this study based on the same trial, SGPV gene expression and the innate and adaptive antiviral immune response was monitored in gills and spleen in the presence and absence of hydrocortisone. Whereas most SGPV genes were induced from day 3 along with the interferon-regulated innate immune response in gills, the putative SGPV virulence genes of the B22R family were expressed already one day after SGPV exposure, indicating a potential role as early markers of SGPV infection. In gills of the hydrocortisone-injected fish infected with SGPV, MX expression was delayed until day 10, and then expression skyrocketed along with the viral peak, gill pathology and mortality occurring from day 14. A similar expression pattern was observed for Interferon gamma (IFNγ) and granzyme A (GzmA) in the gills, indicating a role of acute cytotoxic cell activity in SGPVD. Duplex in situ hybridization demonstrated effects of hydrocortisone on the number and localization of GzmA-containing cells, and colocalization with SGPV infected cells in the gill. SGPV was generally not detected in spleen, and gill infection did not induce any corresponding systemic immune activity in the absence of stress hormone injection. However, in fish injected with hydrocortisone, IFNγ and GzmA gene expression was induced in spleen in the days prior to acute mortality. These data indicate that suppressed mucosal immune response in the gills and the late triggered systemic immune response in the spleen following hormonal stress induction may be the key to the onset of clinical SGPVD.

Project description:MicroPoly(A)Pure kits (Ambion) were used to prepare mRNA from P. salmonis-infected and control Atlantic salmon macrophages. Infected and control (24 h incubation) macrophage mRNA samples were subjected to two rounds of amplification using the MessageAmp aRNA kit (Ambion) and manufacturer's instructions. Approximately 400 ng of macrophage mRNA was used as template in the first round of amplification, yielding 8.1 ug of infected macrophage aRNA and 7.8 ug of control macrophage aRNA. Approximately 1 ug of first-round macrophage aRNA was used as template in the second round of amplification, yielding 81.2 ug of infected macrophage aRNA and 83.3 ug of control macrophage aRNA. Infected and control macrophage aRNA samples were visualized on agarose gels to check quality and quantity. Except for the amounts of aRNA and reverse transcription (RT) primer used, macrophage target labeling reactions and microarray hybridizations were identical. Macrophage target syntheses used 5 ug of second-round aRNA and 5 ug of random primers (Roche). RT primers were mixed with aRNA samples, and nuclease-free H2O (Invitrogen) was added to make 10 ul total volume. Samples were incubated at 70 degrees C 4 min, then placed on ice. RT reactions included 50 mM Tris HCl pH 8.3, 75 mM KCl, 3 mM MgCl2, 10 mM DTT, 0.5 mM each dATP, dCTP, and dGTP, 0.2 mM dTTP, 0.05 mM Cy3-dUTP or Cy5-dUTP (Amersham), 40U RNAguard ribonuclease inhibitor (Amersham), and 400U Superscript II Rnase H- reverse transcriptase (Invitrogen). RT reactions were incubated at 42 degrees C for 2.5 h, followed by addition of 0.025U RNase A (Sigma) and 1.5U RNase H (New England BioLabs) and incubation at 37 degrees C for 30 min. Labeled targets were cleaned using the Qiaquick PCR purification kit (Qiagen) and precipitated, with 300 mM sodium acetate, 1 ul of 20 ug/ul glycogen (Invitrogen), and 2.5 volumes of 100% ethanol, at -20 degrees C overnight. Each labeled target was recovered by centrifugation (14,000 rpm, 4 degrees C, 1 h), washed in 70% ethanol, air-dried, and resuspended in 60 ul of hybridization buffer: 50% deionized formamide, 5X SSC, 0.1% SDS, 5 ul of 5 ug/ul oligo dT (5'T18[Q-N]3'), 5 ul of 2 ug/ul BSA (Pierce), and 2 ul of 10 ug/ul sonicated human placental DNA (Sigma). Targets were incubated at 96 degrees C for 3 min, and then at 65 degrees C until applied to microarrays. Microarrays were prepared for hybridization by washing 2 X 5 min in 0.1% SDS, washing 5 X 1 min in MilliQ H2O, immersing 3 min in 95 degrees C MilliQ H2O, and drying by centrifugation (2000 rpm, 5 min, in 50 ml conical tube). Microarray hybridizations were run in the dark under HybriSlips hybridization covers (Grace Biolabs) in slide hybridization chambers (Corning) submerged in a 45 degrees C water bath for 16 h. Coverslips were floated off in 45 degrees C (1X SSC, 0.2% SDS), and arrays were washed 1 X 10 min in 45 degrees C (1X SSC, 0.2% SDS), 3 X 4 min in room temperature (0.1X SSC, 0.1% SDS), and 4 X 4 min in room temperature 0.1X SSC. Slides were dried by centrifugation as before. Fluorescent images of hybridized arrays were acquired immediately at 10 um resolution using ScanArray Express (PerkinElmer). The Cy3 and Cy5 cyanine fluors were excited at 543 nm and 633 nm respectively, and the same laser power (90%) and photomultiplier tube (PMT) settings were used for all slides in a study (PMT 72 Cy3, PMT 63 or 64 Cy5 for macrophage study). Fluorescent intensity data were extracted from TIF images using Imagene 5.5 software (Biodiscovery). Keywords: other

Dataset Information

Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells.

Publications

Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets