Shrimp miR-1000 Functions in Antiviral Immunity by Simultaneously Triggering the Degradation of Two Viral mRNAs.

Yi Gong,Chenyu Ju,Xiaobo Zhang

doi:10.3389/fimmu.2018.02999

Abstract

MicroRNAs (miRNAs) function as crucial suppressors of gene expression via translational repression or direct mRNA degradation. However, the mechanism of multi-gene regulation by a host miRNA in antiviral immunity has not been extensively explored. In this study, the regulation of two white spot syndrome virus (WSSV) genes by its host (Marsupenaeus japonicus shrimp) miRNA (shrimp miR-1000) was characterized. The miRNA target gene prediction showed that only two virus genes (wsv191 and wsv407) might be the targets of miR-1000. The results of insect cell transfection assays revealed that shrimp miR-1000 could target multiple virus genes (wsv191 and wsv407). The mRNA degradation analysis and RNA FISH (fluorescence in situ hybridization) analysis indicated that miR-1000 triggered the mRNA degradation of target genes through 5′-3′ exonucleolytic digestion in vivo and thereby inhibited the virus infection in shrimp. The miRNA-mediated 5′-3′ exonucleolytic digestion of target mRNAs stopped near the 3′UTR (3′untranslated region) sequence complementary to the seed sequence of miR-1000. Therefore, our study provided novel insights into how a host miRNA targeted multiple viral genes and prevented host from virus infection.

Highlights

It is well known that virus invasion of its host and the host immune response against the virus depend on virus-host interactions [1]
The results from the present study have shown that miR-1000 played a negative role in white spot syndrome virus (WSSV) infection, further data revealed that shrimp miR-1000 could simultaneously target two viral genes, which triggered mRNAs degradations through 5′3′ exonucleolytic digestion, leading to the inhibition of virus infection
The results indicated that when miR-1000 was overexpressed in shrimp (Figure 1B), the WSSV copies and the shrimp mortality were significantly decreased compared with the controls (Figures 1C,D), suggesting that miR-1000 played a negative role during virus infection

Summary

Introduction

It is well known that virus invasion of its host and the host immune response against the virus depend on virus-host interactions [1]. During virus-host interaction, the regulation of gene expression plays an essential role. Given that microRNAs (miRNAs) function as crucial regulators of gene expression [2], their roles in virus-host interactions have attracted more attention in recent years. The silencing of host Drosha and Dicer, two genes required for miRNA biogenesis, leads to a decreased mature miRNAs production and increases host sensitivity to virus infection [8]. These findings suggest that host and virus miRNAs are required in the regulation of virushost interactions. Virus miRNAs can target host genes or virus genes

Methods

Results

Conclusion