Spontaneous induction of interferon signaling in zebrafish larvae

We generated transgenic zebrafish that report on interferon signaling through expression of GFP from the isg15 promoter. We repeatedly observed seemingly spontaneous induction of this reporter in zebrafish larvae at 8 days post-fertilization, and hypothesized that these animals were infected by viruses. To test this hypothesis, we isolated RNA from pools of GFP-negative and GFP-positive larvae to prepare for sequencing. Three independent untreated clutches of isg15:GFP animals were screened for GFP expression and separated as GFP-negative and GFP-positive. 30 individuals were pooled per group. Three isg15:GFP and two Wt (GFP-negative) clutches were collected at 8 dpf. RNA was extracted by mechanical lysis with TRIzol and DNAse-treated. Libraries were prepared with the Illumina TruSeq Stranded Total RNA Ribo-Zero Gold kit, and were sequenced on a Illumina HiSeq 2500 by 125 cycle paired-end sequencing v4.