Distinct Host Gene Expression Patterns Induced by Covert Deformed Wing Virus Infections in Honeybees (Apis mellifera)

Deformed Wing Virus (DWV) is a widespread insect pathogen and a major contributor to honeybee colony losses. While overt infections cause characteristic deformities and behavioral changes, covert or low-level infections remain poorly understood. Here, we hypothesize that nonsymptomatic DWV infections induce distinct host transcriptional responses compared to symptomatic cases, which may influence the ultimate outcome of infection. Transcriptomic analysis of Apis mellifera anatoliaca worker bees from an experimental apiary revealed a high DWV RNA load in a minority of colonies. Assembly of the viral genome from these asymptomatic colonies identified a novel DWV-A/DWV-B recombinant (DWV_Ord1; GenBank Accession PX394756). Comparative gene expression analysis showed that covertly infected bees upregulated several genes associated with venom production, cuticular integrity, and light perception, suggesting heightened defensive readiness. These results provide insight into early molecular responses to DWV and identify potential biomarkers of low-level infection in honeybee colonies.