The Iflaviruses Sacbrood virus and Deformed wing virus evoke different transcriptional responses in the honeybee which may facilitate their horizontal or vertical transmission
Sacbrood virus (SBV) and Deformed wing virus (DWV) are evolutionarily related positive-strand RNA viruses, members of the Iflavirus group. They both infect the honeybee Apis mellifera but have strikingly different levels of virulence when transmitted orally. Honeybee larvae orally infected with SBV usually accumulate high levels of the virus, which halts larval development and causes insect death. In contrast, oral DWV infection at the larval stage usually causes asymptomatic infection with low levels of the virus, although high doses of ingested DWV could lead to DWV replicating to high levels. We investigated effects of DWV and SBV infection on the transcriptome of honeybee larvae and pupae using global RNA-Seq and real-time PCR analysis. This showed that high levels of SBV replication resulted in down-regulation of the genes involved in cuticle and muscle development, together with changes in expression of putative immune-related genes. In particular, honeybee larvae with high levels of SBV replication, with and without high levels of DWV replication, showed concerted up-regulated expression of antimicrobial peptides (AMPs), and down-regulated expression of the prophenoloxidase activating enzyme (PPAE) together with up-regulation of the expression of a putative serpin, which could lead to the suppression of the melanisation pathway. The effects of high SBV levels on expression of these immune genes were unlikely to be a consequence of SBV-induced developmental changes, because similar effects were observed in honeybee pupae infected by injection. In the orally infected larvae with high levels of DWV replication alone we observed no changes of AMPs or of gene expression in the melanisation pathway. In the injected pupae, high levels of DWV alone did not alter expression of the tested melanisation pathway genes, but resulted in up-regulation of the AMPs, which could be attributed to the effect of DWV on the regulation of AMP expression in response to wounding. We propose that the difference in expression of the honeybee immune genes induced by SBV and DWV may be an evolutionary adaptation to the different predominant transmission routes used by these viruses.
[…] The RNA-Seq reads were aligned using Bowtie2 () (with the least stringent alignment settings to allow detection of the sequence variants, “–very-sensitive” option) to the latest honeybee transcriptome annotation (OGS3; containing 16,041 putative transcripts), as well as to a set of sequences of the known fungal and viral pathogens of the honeybees used previously (; ). We used samtools idxstats to produce a summary of the number of reads aligning to the honeybee transcriptome and the DWV and SBV reference sequences (GenBank accession numbers NC˙004830and AF092924respectively). The Next Generation Sequencing (NGS) gene expression profiles were used to identify differentially expressed (DE) genes using DESeq () and edgeR (), with adjusted p-values and a false discovery rate (FDR) below 0.05. Drosophila homologues of the honeybee genes were identified previously () and those DE in the contrasts were used for Gene Ontology (GO) analysis () using AmiGO (). […]
to analyse the site's operation and effectiveness, to display ads tailored to your interests
and to provide you with relevant promotional messages and other information about products,
events and services of ours or our sponsors and partner companies.
These cookies are needed for the site to work and to be optimized.
These cookies are needed to interact with the social network plugins on this site.
These cookies are used to track visitors across websites.
The intention is to display ads that are relevant and engaging for the users.
These cookies are needed in order to better understand how
this site is used and to improve the user experience.
At omicX, we believe trust is of the utmost importance. Transparency allows trust.
This is why we want you to understand what data we collect and how we use it.