MicroRNAs (miRNAs) are small, non-coding single stranded RNAs that play crucial roles in numerous biological processes. Vertebrate herpesviruses encode multiple viral miRNAs that modulate host and viral genes. However, the roles of viral miRNAs in lower vertebrates have not been fully determined. In a recent study, high-throughput sequencing was used to analyse the miRNA and mRNA expression profiles of Carassius auratus gibelio in response to infection by cyprinid herpesvirus 2 (CyHV-2).

RNA sequencing obtained 26,664 assembled transcripts, including 2,912 differentially expressed genes. Based on small RNA sequencing and secondary structure predictions, we identified 17 CyHV-2 encoded miRNAs, among which 14 were validated by stem-loop quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and eight were validated by northern blotting. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of miRNAs-mRNA pairs revealed diverse affected immune signalling pathways, including the RIG-I-like receptor and JAK-STAT pathways. Finally, four genes were presented to be involved in RIG-I-like pathways, including host gene IRF3, RBMX, PIN1, viral gene ORF4, which are negatively regulated by CyHV-2 encoded miRNA miR-C4.

This study is the first to provide a comprehensive overview of viral miRNA-mRNA co-regulation, which might have a key role in controlling post-transcriptomic regulation during CyHV-2 infection.

 

The level of CyHV-2 and the DEGs in the kidney of silver crucian carp.

Samples were collected at 0, 12, 24, 48, and 72 h after challenged with CyHV-2. (A) The accumulation curve of CyHV-2 in the kidney of silver crucian carp. Viruses were titrated using a real-time PCR approach. (B) The relative expression levels of MAPK7, MHC-I, and NF- κB; (C) IRF3, RBMX, and PIN1 in the kidney, β-actin served as the reference gene. Results are presented as mean ± SD of 3 independent experiments, *P < 0.05, **P < 0.01.

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Reference
J. Lu, D. Xu, Y. Jiang, S. Kong, Z. Shen, S. Xia, L. Lu (2017) Integrated analysis of mRNA and viral miRNAs in the kidney of Carassius auratus gibelio response to cyprinid herpesvirus 2 Scientific Reports 7:13787 doi:10.1038/s41598-017-14217-y [abstract]

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