Transcriptome analysis of honey bee (Apis mellifera) pupae in response to in-vitro infection with Israel Acute Paralysis Virus (IAPV)

The Honey bee (Apis mellifera) is the most economically valuable pollinator of agricultural and horticultural crops with a market value that exceeds 14.6 billion dollars per year. Over the last decade honey bees have suffered unexplained losses, raising serious concerns about the long-term availability of honey bee-assisted pollination of our crops. 

Honey bee viruses, and picorna-like viruses in particular, have been associated with declining honey bee health and can cause serious disease.  However, these viruses are understudied and almost nothing is known on their interaction with the honey bee host. Recently, we have developed a honey bee study model using in vitro inoculation of Israel Acute Paralysis Virus (IAPV) into pupae. Initial RT-qPCR studies of a small set of genes showed a transcriptional disturbance of the ribosomal biogenesis pathway, indicating a disruption of cellular translation by IAPV, as it would be typical for picornaviruses. Based on these results, a full transcriptome analysis of IAPV infected honey bee pupae was performed using a standard RNAseq protocol on an Illumina HiSeq 2000). Altogether, 300 million reads were generated that comprised four time points of the IAPV infection (0h, 5h, 20h and 48h) in three different treatment group (without manipulation, PBS-injection control, and IAPV-injected bees). Reads were mapped to the new Apis mellifera genome assemble (Amel4.5) using Tophat software, and gene expression patterns were analyzed using Cufflinks and Cuffcompare. Approximately six hundred genes were differentially expressed in response to virus infection. Gene ontology analysis using Blast2Go software revealed enrichment in functional categories including cell signaling proteins. This study complements our understanding of IAPV pathogenesis in honey bees. Possible mechanisms and the implications for honey bee health and the comparative biology of picornaviruses will be discussed.