ABSTRACT: Purpose: The goals of this study are to investigate the differentially expressed miRNAs between ALV-J infected (WRR+) and uninfected (WRR-)chickens spleens by Illumina deep sequencing. Methods: 140-day-old female chickens of White Recessive Rock (WRR) were confirmed as J subgroup avian leukosis virus (ALV-J) infection. Total RNA from three ALV-J-infected spleens (designated: WRR1+, WRR2+, WRR3+) and three uninfected normal spleen samples (designated: WRR1-, WRR2-, WRR3-) was isolated by TRIzol following the manufacturer’s instruction (Invitrogen, CA, USA). RNA samples of three individuals within each group were pooled with equal amounts, and then were subjected to Illumina deep sequencing by Illumina Hiseq 2500. Results: After raw data filtered, 12,150,275 and 15,227,930 reads of 18-32 bp, representing 569,847 and 543,062 unique sequences, were obtained for WRR- and WRR+ libraries, respectively. Through blasting with the chicken reference genome, 360,180 WRR- sequences and 327,391 WRR+ sequences, which accounted for more than 60% of the unique sequences, were perfectly matched.To analyze the miRNA detection efficiency of Illimuna deep sequencing, all the clean reads were blasted with the Rfam data base 10.1, annotated and then removed rRNA, tRNA, snoRNA and other snRNAs. The annotation results revealed that miRNAs accounted for more than 68% of all clean reads in the WRR− and WRR+ libraries. In this study, a total of 476 miRNAs were identified after compared the unique sequences against the chicken miRNAs precursors in miRBase 18.0. Base on unique sequences matched counts, 167 differential expression miRNAs were identified by DEGseq package using Benjamini-q-value of 0.001 as a cut-off. In ALV-J infected spleens, 83 miRNAs showed up-regulated expression and 84 were down-regulated when compared to uninfected samples. Conclusions: Our study represents the first time to analysis of miRNA Expression in Spleen of J Subgroup Avian Leukosis Virus (ALV-J) Infected (WRR+) and Uninfected (WRR-) Broilers. A total of 167 miRNAs were found to be differentially expressed in ALV-J infected spleens when compared to uninfected chickens. These miRNAs can be considered as candidates for further study ALV-J invasion.
