Parallel epigenomic and transcriptomic responses to viral infection in honey bees, Apis mellifera

Honeys bees are a critical pollinator of a wide variety of agricultural crops, but beekeepers experience heavy annual losses of honey bee colonies. Several factors are associated with colony losses, in particular infection with Israeli Acute Paralysis Virus (IAPV). Despite the importance of viruses to honey bee health, our understanding of the molecular mechanisms mediating host-pathogen interactions is limited. We examined the transcriptional and epigenetic (DNA methylation) responses to acute IAPV infection in honey bee workers. We found significant expression differences in genes associated with several immune and epigenetic pathways. However, IAPV-regulated genes did not overlap significantly with genes that respond to bacterial or microsporidian infection, suggesting that honey bees utilize distinct pathways for different immune challenges. Additionally, DNA methylation status of several genes changed significantly, including genes that have been linked to antiviral immune responses in humans.  Interestingly, there was no significant overlap between the differentially methylated and differentially expressed genes, suggesting that honey bees may possess parallel genomic mechanisms to respond to viral infection.