title: Impact of asymptomatic nodavirus carrier state and intraperitoneal viral mimic injection on brain transcript expression in Atlantic cod (Gadus morhua).
abstract: Nodaviruses and other RNA viruses have a profoundly negative impact on the global aquaculture industry. Nodaviruses target nervous tissue causing viral nervous necrosis, a disease characterized by neurological damage, swimming abnormalities, and morbidity. This study used functional genomic techniques to study the Atlantic cod (Gadus morhua) brain transcript expression responses to asymptomatic high nodavirus carrier state and intraperitoneal injection of polyriboinosinic polyribocytidylic acid (pIC). Reciprocal suppression subtractive hybridization (SSH) cDNA libraries enriched for virus-responsive brain transcripts were constructed and characterized. We generated 1,938 expressed sequence tags (ESTs) from a forward brain SSH library (enriched for transcripts upregulated by nodavirus and/or pIC) and 1,980 ESTs from a reverse brain SSH library (enriched for transcripts downregulated by nodavirus and/or pIC). To examine the effect of nodavirus carrier state on individual brain gene expression in asymptomatic cod, 27 transcripts of interest were selected for quantitative reverse transcription-polymerase chain reaction (QPCR) studies. Transcripts found to be >10-fold upregulated in individuals with a high nodavirus carrier state relative to those in a no/low nodavirus carrier state were identified as ISG15, IL8, DHX58 (alias LGP2), ZNFX1, RSAD2 (alias viperin), and SACS (sacsin, alias spastic ataxia of Charlevoix-Saguenay). These and other SSH-identified transcripts were also found by QPCR to be significantly (P < 0.05) upregulated by pIC compared with saline-injected controls within 72 h of injection. Several transcripts identified in the reverse SSH library, including two putative ubiquitination pathway members (HERC4 and SUMO2), were found to be significantly (P < 0.05) downregulated in individuals with a high nodavirus carrier state. Our data shows that Atlantic cod brains have a strong interferon pathway response to asymptomatic high nodavirus carrier state and that many interferon pathway and other immune relevant transcripts are significantly induced in brain by both nodavirus and pIC.
authors.affiliation: Ocean Sciences Centre, Memorial University of Newfoundland, 1 Marine Lab Road, St. John's, Newfoundland, Canada. mrise@mun.ca
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Rise
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Hall
authors.forename: Marlies
authors.initials: M
authors.lastname: Rise
authors.forename: Tiago S
authors.initials: TS
authors.lastname: Hori
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Browne
authors.forename: A Kurt
authors.initials: AK
authors.lastname: Gamperl
authors.forename: Sophie
authors.initials: S
authors.lastname: Hubert
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kimball
authors.forename: Sharen
authors.initials: S
authors.lastname: Bowman
authors.forename: Stewart C
authors.initials: SC
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D020224:Expressed Sequence Tags; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology / Q000821:virology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D048389:Gadus morhua / Q000235:genetics / Q000821:virology*; D020869:Gene Expression Profiling; D015723:Gene Library; D007274:Injections, Intraperitoneal; D030381:Nodaviridae / Q000502:physiology*; D009693:Nucleic Acid Hybridization; D011070:Poly I-C / Q000008:administration & dosage; D012327:RNA Virus Infections / Q000235:genetics / Q000378:metabolism / Q000662:veterinary
chemical_list: D029941:Fish Proteins; D011070:Poly I-C