The microRNA pathway activation in insect cell model upon Autographa californica multiple nucleopolyhedrovirus infection

Background:The immune system of insects exerts fundamentally different antiviral mechanisms than mammals.MicroRNAs(miRNAs)play vital roles in developing insect antiviral immunity.MiRNAs expression profiles of insects changed significantly during baculovirus infection.Methods:Differential expression profiles of miRNAs in Spodoptera frugiperda were monitored by next-generation sequencing(NGS)and RT-qPCR during Autographa californica multiple nucleopolyhedrovirus(AcMNPV)infection.The transcription levels of genes were detected by RT-qPCR.The 50%tissue culture infective dose(TCID_(50))endpoint dilution assay was used to determine the proliferation of progeny virus.Results:NGS revealed that 49 miRNAs were differentially expressed in Sf9 cells,and 10 of them were significantly up-or down-regulated.Though RT-qPCR analysis,we observed the similar trends for the expression patterns of significantly differentially expressed miRNAs from NGS.Moreover,the transcription levels of core genes,Exportin5,Dicer1,and Argonaute1,in miRNA biogenesis pathways were significantly increased after AcMNPV infection.For five selected miRNAs,miR-34-5p could regulate the proliferation of baculovirus progeny virus and energy metabolism.Conclusion:The miRNAs biogenesis pathway in Sf9 cells plays an important role and may be stimulated to resist AcMNPV infection.This work provides evidence for the molecular mechanism of baculovirus-insect interaction and offers novel ideas and directions for green pest control technology.

A novel domain-duplicated SlitFAR3 gene involved in sex pheromone biosynthesis in Spodoptera litura

Fatty acyl reductases(FARs)are key enzymes that participate in sex pheromone biosynthesis by reducing fatty acids to fatty alcohols.Lepidoptera typically harbor numerous FAR gene family members.Although FAR genes are involved in the biosynthesis of sex pheromones in moths,the key FAR gene of Spodoptera litura remains unclear.In this work,we predicted 30 FAR genes from the S.litura genome and identified a domain duplication within gene SlitFAR3,which exhibited high and preferential expression in the sexually mature female pheromone glands(PGs)and a rhythmic expression pattern during the scotophase of sex pheromone production.The molecular docking of SlitFAR3,as predicted using a 3D model,revealed a co-factor NADPH binding cavity and 2 substrate binding cavities.Functional expression in yeast cells combined with comprehensive gas chromatography indicated that the SlitFAR3 gene could produce fatty alcohol products.This study is the first to focus on the special phenomenon of FAR domain duplication,which will advance our understanding of biosynthesis-related genes from the perspective of evolutionary biology.