Table_1_Transcriptome Profiling Reveals a Novel Mechanism of Antiviral Immunity Upon Sacbrood Virus Infection in Honey Bee Larvae (Apis cerana).XLSX

The honey bee is one of the most important pollinators in the agricultural system and is responsible for pollinating a third of all food we eat. Sacbrood virus (SBV) is a member of the virus family Iflaviridae and affects honey bee larvae and causes particularly devastating disease in the Asian honey bees, Apis cerana. Chinese Sacbrood virus (CSBV) is a geographic strain of SBV identified in China and has resulted in mass death of honey bees in China in recent years. However, the molecular mechanism underlying SBV infection in the Asian honey bee has remained unelucidated. In this present study, we employed high throughput next-generation sequencing technology to study the host transcriptional responses to CSBV infection in A. cerana larvae, and were able to identify genome-wide differentially expressed genes associated with the viral infection. Our study identified 2,534 differentially expressed genes (DEGs) involved in host innate immunity including Toll and immune deficiency (IMD) pathways, RNA interference (RNAi) pathway, endocytosis, etc. Notably, the expression of genes encoding antimicrobial peptides (abaecin, apidaecin, hymenoptaecin, and defensin) and core components of RNAi such as Dicer-like and Ago2 were found to be significantly upregulated in CSBV infected larvae. Most importantly, the expression of Sirtuin target genes, a family of signaling proteins involved in metabolic regulation, apoptosis, and intracellular signaling was found to be changed, providing the first evidence of the involvement of Sirtuin signaling pathway in insects’ immune response to a virus infection. The results obtained from this study provide novel insights into the molecular mechanism and immune responses involved in CSBV infection, which in turn will contribute to the development of diagnostics and treatment for the diseases in honey bees.

蜜蜂是农业生态系统中最为关键的传粉者之一，为人类膳食中三分之一的粮食作物承担传粉服务。囊状幼虫病病毒（Sacbrood virus, SBV）隶属于Iflaviridae病毒科，可侵染蜜蜂幼虫，对东方蜜蜂（Apis cerana）造成极具破坏性的病害。中国囊状幼虫病病毒（Chinese Sacbrood virus, CSBV）是SBV在中国境内发现的地理株系，近年来已引发中国境内蜜蜂大规模死亡。然而，东方蜜蜂感染SBV的分子机制至今仍未阐明。本研究采用高通量下一代测序技术，探究东方蜜蜂幼虫感染CSBV后的宿主转录响应，并成功鉴定出与病毒感染相关的全基因组差异表达基因。本研究共识别出2534个差异表达基因（differentially expressed genes, DEGs），涉及宿主先天免疫通路，包括Toll通路、免疫缺陷（immune deficiency, IMD）通路、RNA干扰（RNA interference, RNAi）通路、内吞作用等。值得注意的是，编码抗菌肽（abaecin、apidaecin、hymenoptaecin、defensin）以及RNAi核心组分（如Dicer样蛋白与Ago2）的基因在CSBV感染的幼虫中显著上调。最为关键的是，沉默信息调节因子（Sirtuin）靶基因——一类参与代谢调控、细胞凋亡及细胞内信号转导的信号蛋白家族——的表达发生显著改变，这首次证实了Sirtuin信号通路参与昆虫对病毒感染的免疫应答。本研究结果为解析CSBV感染相关的分子机制与免疫应答提供了全新视角，同时将助力蜜蜂相关病害的诊断与治疗方案开发。