Functional analysis of a putative Bombyx mori cypovirus miRNA BmCPV‐miR‐10 and its effect on virus replication

Abstract

Bombyx mori cypovirus (BmCPV) is an important pathogen of silkworm (B. mori), the economically beneficial insect. The mechanism of its interaction with host immune defence system in the process of infection is still not yet completely clear. Researches have demonstrated that virus‐encoded microRNAs (miRNA) play a crucial role in regulating host–pathogen interaction, but few reports are available so far on miRNAs encoded by insect viruses, especially the RNA viruses. In this study, a putative miRNA encoded by the 10th segment of BmCPV genomic RNA, BmCPV‐miR‐10, was identified and functionally analysed. The expression of the putative BmCPV‐miR‐10 could be detected via stem‐loop RT‐PCR (reverse transcription‐Polymerase Chain Reaction) in the midgut of silkworm larvae infected with BmCPV. BmCSDE1 (B. mori cold shock domain E1 protein) gene was predicted to be a candidate target gene for BmCPV‐miR‐10 with the miRNA binding site located in 3′ untranslated region of its mRNA. The regulation effect of the putative BmCPV‐miR‐10 on BmCSDE1 was verified in HEK293 cells by lentiviral expression system, in BmN cells by transfecting BmCPV‐miR‐10 mimics. The qRT‐PCR (quantitative real‐time PCR) results showed that the putative BmCPV‐miR‐10 could suppress the expression of BmCSDE1. By injection of BmCPV‐miR‐10 mimics into the silkworm larvae infected with BmCPV, it was further proved that the putative BmCPV‐miR‐10 could suppress the expression of BmCSDE1 in vivo, then inhibit the expression of BmApaf‐1 (B. mori apoptotic protease activating factor 1), while enhance the replication of BmCPV genomic RNAs to a certain extent. These results implied that the putative BmCPV‐miR‐10 could down‐regulate the expression of BmCSDE1, then suppress the expression of BmApaf‐1, thereby created a favourable intracellular environment for virus replication and proliferation.

Downregulation of miR-1388 Regulates the Expression of Antiviral Genes via Tumor Necrosis Factor Receptor (TNFR)-Associated Factor 3 Targeting Following poly(I:C) Stimulation in Silver Carp (Hypophthalmichthys molitrix)

“…Research indicates that miRNAs can directly target viral genes, thereby regulating viral replication and controlling viral infections [ 34 , 35 ]. Consequently, virus-induced alterations in host miRNA expression or the production of beneficial miRNAs can enable the evasion of host immune recognition and clearance, thereby facilitating immune evasion [ 36 , 37 ]. Furthermore, miRNAs have the capability to target host immune genes, activate immune-related pathways, and consequently modulate the host immune response [ 38 , 39 ].…”

Advances in the Immune Regulatory Role of Non-Coding RNAs (miRNAs and lncRNAs) in Insect-Pathogen Interactions

“…Similarly, BmCPV-miR-10 downregulated the B. mori cold shock domain E1 protein (BmCSDE1) mRNA expression level after binding to its 3’UTR in the infected larvae. BmCPV-miR-10 also inhibited the expressional changes of B. mori apoptotic protease activating factor 1 (BmApaf-1) during in vivo infection, creating suitable conditions for virus replication and proliferation ( 167 ). BmCPV-miR-1 inhibited cell apoptosis in the infected silkworm via increasing B. mori inhibitor of apoptosis protein (BmIAP) expression, promoting the virus replication ( 168 ).…”

The Spatio-Temporal Expression Profiles of Silkworm Pseudogenes Provide Valuable Insights into Their Biological Roles

“…The silkworm pangenome project have provided a large-scale genetic resource (such as genome assemblies, genomic variations and traits) for research communities, therefore, laid a foundation to study the relationships between traits and genomes. 15 However, most genomic variations are located outside of protein-coding genic regions, therefore, it’s urgent to obtain more comprehensive genome annotations, such as miRNA, 22 , 23 lncRNA, 24 smORF, 25 and pseudogenes. Researches involves in pseudogenes silkworms are limited.…”