De Novo Transcriptome Analysis Shows That SAV-3 Infection Upregulates Pattern Recognition Receptors of the Endosomal Toll-Like and RIG-I-Like Receptor Signaling Pathways in Macrophage/Dendritic Like TO-Cells.
A fundamental step in cellular defense mechanisms is the recognition of "danger signals" made of conserved pathogen associated molecular patterns (PAMPs) expressed by invading pathogens, by host cell germ line coded pattern recognition receptors (PRRs). In this study, we used RNA-seq and the Kyoto encyclopedia of genes and genomes (KEGG) to identify PRRs together with the network pathway of differentially expressed genes (DEGs) that recognize salmonid alphavirus subtype 3 (SAV-3) infection in macrophage/dendritic like TO-cells derived from Atlantic salmon (Salmo salar L) headkidney leukocytes. Our findings show that recognition of SAV-3 in TO-cells was restricted to endosomal Toll-like receptors (TLRs) 3 and 8 together with RIG-I-like receptors (RLRs) and not the nucleotide-binding oligomerization domain-like receptors NOD-like receptor (NLRs) genes. Among the RLRs, upregulated genes included the retinoic acid inducible gene I (RIG-I), melanoma differentiation association 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2). The study points to possible involvement of the tripartite motif containing 25 (TRIM25) and mitochondrial antiviral signaling protein (MAVS) in modulating RIG-I signaling being the first report that links these genes to the RLR pathway in SAV-3 infection in TO-cells. Downstream signaling suggests that both the TLR and RLR pathways use interferon (IFN) regulatory factors (IRFs) 3 and 7 to produce IFN-a2. The validity of RNA-seq data generated in this study was confirmed by quantitative real time qRT-PCR showing that genes up- or downregulated by RNA-seq were also up- or downregulated by RT-PCR. Overall, this study shows that de novo transcriptome assembly identify key receptors of the TLR and RLR sensors engaged in host pathogen interaction at cellular level. We envisage that data presented here can open a road map for future intervention strategies in SAV infection of salmon.
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Ullevålsveien 72, P.O. Box 8146 Dep NO-0033 Oslo, Norway. cheng.xu@nmbu.no.
Cheng
C
Xu
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Ullevålsveien 72, P.O. Box 8146 Dep NO-0033 Oslo, Norway. oystein.evensen@nmbu.no.
Øystein
Ø
Evensen
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Ullevålsveien 72, P.O. Box 8146 Dep NO-0033 Oslo, Norway. hetroney.mweemba.munangandu@nmbu.no.
Hetron
HM
Munang'andu
D000524:Alphavirus / Q000502:physiology*; D018354:Alphavirus Infections / Q000235:genetics / Q000378:metabolism / Q000821:virology; D000818:Animals; D002460:Cell Line; D019295:Computational Biology / Q000379:methods; D000071457:DEAD Box Protein 58 / Q000235:genetics* / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism / Q000821:virology; D011992:Endosomes / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D063990:Gene Ontology; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000821:virology; D012474:Salmon; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
D051193:Toll-Like Receptors; D000071457:DEAD Box Protein 58
Pattern recognition receptor (PRR); RIG-I-like receptor (RLR); RNA sequencing (RNA-Seq); Salmonid alphavirus subtype 3 (SAV-3); TO-cells; Toll-like receptor (TLR); dendritic cells; macrophages