Identification of Immune Response to Sacbrood Virus Infection in Apis cerana Under Natural Condition.

Shuai Deng,Yanchun Deng,Sa Yang,Dahe Yang,Hongxia Zhao,Chunsheng Hou,Shuo Shen

doi:10.3389/fgene.2020.587509

Abstract

Chinese sacbrood virus (CSBV) is a serious threat to eastern honeybees (Apis cerana), especially larvae. However, the pathological mechanism of this deadly disease remains unclear. Here, we employed mRNA and small RNA (sRNA) transcriptome approach to investigate the microRNAs (miRNAs) and small interfering RNAs (siRNAs) expression changes of A. cerana larvae infected with CSBV under natural condition. We found that serine proteases involved in immune response were down-regulated, while the expression of siRNAs targeted to serine proteases were up-regulated. In addition, CSBV infection also affected the expression of larvae cuticle proteins such as larval cuticle proteins A1A and A3A, resulting in increased susceptibility to CSBV infection. Together, our results provide insights into sRNAs that they are likely to be involved in regulating honeybee immune response.

Highlights

The Asian honeybee, Apis cerana, is an important pollinator to maintain plant biodiversity in Southeast Asian countries, especially to wild flowering plants and crops (Ai et al, 2012)
Chinese sacbrood virus (CSBV)-infected larvae were taken from the colonies with obvious cystic symptoms and confirmed it using RT-PCR with a pair of specific primers, 5 -CCTGGGAAGTTTGCTAGTATTTACG3 and 5 -CCTATCACATCCATCTGGGTCAG-3 according to the described by Ma et al (2013) and the healthy larvae were collected from three different apiaries (Huludao and Benxi in Liaoning Province, and Guangzhou in Guangdong province)
The expression of Dicer-like and Argonaute-2 (Ago2) genes associated to the RNA interference (RNAi) pathway were up-regulated (Supplementary Table 5 and Supplementary Figure 4), we focused on small interfering RNAs (siRNAs) related to serine/threonine kinase, serinetype endopeptidase and serine-type peptidase genes based on the analysis of mRNA and miRNA data

Summary

INTRODUCTION

The Asian honeybee, Apis cerana, is an important pollinator to maintain plant biodiversity in Southeast Asian countries, especially to wild flowering plants and crops (Ai et al, 2012). The full-genome sequence of A. cerana was determined, providing new insights into physiological resistance to Varroa mites, and was found to have six more immune genes than Apis mellifera (Diao et al, 2018b). Virus-derived small interfering RNAs (vsiRNA) produced during the viral infection are a group of siRNA ranged from 21 to 24 nt in size that may hijack the host RNAi pathway (Aliyari et al, 2008). VsiRNA guides the RNA induced silencing complex (RISC) to target viral genomes, which can potentially alter the host transcriptome responses (Ding, 2010; Yang et al, 2018). Our results provide insights into up- and down-regulated in cuticle protein and serine proteinase during CSBV infection

MATERIALS AND METHODS

DISCUSSION

Findings

DATA AVAILABILITY STATEMENT