miRNAs in Insects Infected by Animal and Plant Viruses

Abstract

Viruses vectored by insects cause severe medical and agricultural burdens. The process of virus infection of insects regulates and is regulated by a complex interplay of biomolecules including the small, non-coding microRNAs (miRNAs). Considered an anomaly upon its discovery only around 25 years ago, miRNAs as a class have challenged the molecular central dogma which essentially typifies RNAs as just intermediaries in the flow of information from DNA to protein. miRNAs are now known to be common modulators or fine-tuners of gene expression. While recent years has seen an increased emphasis on understanding the role of miRNAs in host-virus associations, existing literature on the interaction between insects and their arthropod-borne viruses (arboviruses) is largely restricted to miRNA abundance profiling. Here we analyse the commonalities and contrasts between miRNA abundance profiles with different host-arbovirus combinations and outline a suggested pipeline and criteria for functional analysis of the contribution of miRNAs to the insect vector-virus interaction. Finally, we discuss the potential use of the model organism, Drosophila melanogaster, in complementing research on the role of miRNAs in insect vector-virus interaction.

Keywords: arbovirus; host-virus interaction; insect virus; miRNA; plant virus.

Figure 1

Suggested pipeline and criteria for analysis of the miRNA function in host-virus interaction. Identification of miRNAs with important roles in host-virus interactions typically starts with miRNA profiling. Comparison of uninfected and infected samples commonly identify many miRNAs with differential abundance upon infection. Especially for pilot studies, miRNA screening and miRNA prioritisation using the outlined criteria (in yellow-shaded boxes, left panel) will help streamline and focus research. Identification of targets by bioinformatics also generate many putative mRNA targets. Screening using the outlined criteria (in yellow-shaded boxes, right panel) will as well aid in narrowing down the putative targets. Once miRNA of interest has been identified, and its target confirmed, a closed-loop inter-relationship amongst the (1) miRNA, (2) target gene, (3) virus, and (4) host has to be confirmed (centre panel) to categorically identify the miRNA-target pair as being relevant in the host-virus interaction. Where LOF/GOF mutants exist, identification of relevant miRNAs can start with genetic screens (left panel).