title: Transcriptome analysis of rainbow trout infected with high and low virulence strains of infectious hematopoietic necrosis virus.
abstract: There are three main genetic lineages or genogroups of Infectious hematopoietic necrosis virus (IHNV) in N. America. Strains representing the M genogroup are more virulent in rainbow trout relative to the U genogroup. In this study, we used microarray analysis to evaluate potential mechanisms responsible for host-specific virulence in rainbow trout that were given intraperitoneal injections of buffer or a representative M or U type virus strain. Reverse transcriptase quantitative PCR (RT-qPCR) was used to assess viral load and gene expression of select immune genes. Viral load was significantly higher in trout infected with the M virus starting at 24h post-infection (p.i.) and continuing until 72 h p.i. Microarray analysis of the 48 h time point revealed 153 up-regulated and 248 down-regulated features in response to M virus infection but only 62 up-regulated and 49 down-regulated features following U virus infection. Translation and transcription features were among the most frequent down-regulated features in response to M virus infection and may be associated with the host cell shutoff phenomenon. A greater host cell shutoff response by the M virus may facilitate subversion of the host cell transcriptional machinery and enhance viral replication, suggesting the M virus may be better optimized to manipulate the rainbow trout transcriptional and translational machinery. Anti-viral associated features were the most commonly up-regulated features. A common set of features were up-regulated in both the M and U infection groups, but were induced to a higher magnitude in the M infection group. Gene expression of the anti-viral genes Mx-1 and Vig-1 was correlated but not entirely dependent on viral load in the anterior kidney. Slower replication of the U virus may allow the host more time to induce protective anti-viral immune mechanisms.
authors.affiliation: Western Fisheries Research Center, US Geological Survey, 6505 NE 65th Street, Seattle, WA 98115, USA. mpurcell@usgs.gov
authors.forename: Maureen K
authors.initials: MK
authors.lastname: Purcell
authors.forename: Inderjit Singh
authors.initials: IS
authors.lastname: Marjara
authors.forename: William
authors.initials: W
authors.lastname: Batts
authors.forename: Gael
authors.initials: G
authors.lastname: Kurath
authors.forename: John D
authors.initials: JD
authors.lastname: Hansen
mesh_terms: D000818:Animals; D005393:Fish Diseases / Q000378:metabolism / Q000821:virology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology*; D029142:Infectious hematopoietic necrosis virus / Q000145:classification / Q000472:pathogenicity*; D017686:Oncorhynchus mykiss; D018353:Rhabdoviridae Infections / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D019562:Viral Load; D014774:Virulence