Honey bees are important pollinators of agricultural crops and plant species that enhance ecosystem biodiversity. High annual mortality of US honey bee colonies (averaging 33% since 2006) impacts everyone, as approximately 1/3 of the crops grown to sustain the typical Western diet rely on honey bees for pollination (including many fruit, nut, vegetable, and oil seed crops). Agriculturalists, beekeepers, citizens, and scientists are concerned about honey bee colony losses, which have been associated with virus infection, as well as other abiotic and biotic factors. Though viruses play a role in honey bee colony losses, the mechanisms important to honey bee antiviral defense remain largely uncharacterized. To address this knowledge gap, the Flenniken laboratory is performing experiments in individual bees and cultured cells that will determine the roles of specific honey bee encoded proteins in sensing and responding to viral pathogens. Better understanding of honey bee antiviral defense mechanisms may lead to development of strategies that mitigate virus-associated colony losses, which would in turn broadly impact agricultural and ecological systems that rely on honey bees as pollinators. This project involves undergraduate and graduate students who are performing experiments and are involved in the development and expansion of undergraduate, graduate, and community courses, that utilize honey bees as a model to explain topics in virology, genetics, and biotechnology, while underscoring the importance of pollinators in all ecosystems and the role of basic science in addressing problems of global scale, including loss of bee pollinators.
All organisms have evolved mechanisms to detect and respond to pathogens. A crucial aspect of innate immune mechanisms is recognition of non-self molecules including double-stranded RNA (dsRNA) produced by replicating viruses. The RNA interference (RNAi) mechanism, which results in degradation of viral RNA in a sequence-specific manner, is the primary antiviral defense mechanism for solitary insects, including fruit flies and mosquitoes. Honey bees, which are eusocial insects that live in colonies comprised of over 40,000 individuals, utilize RNAi and a non-sequence specific dsRNA-mediated immune response. The effects of viruses at both the individual bee and colony (super-organism) levels are not well understood, though massive mortality of individual bees will result in death of the entire colony. In individual bees, virus infections can remain asymptomatic, cause paralysis, and/or result in death. These differential outcomes are largely dependent on host immune responses, yet the mechanisms of honey bee antiviral responses require further elucidation. The aim of this project is to determine the mechanisms of honey bee host antiviral defense. To accomplish this goal, the Flenniken laboratory is performing virus infection trials in both individual bees (in vivo) and in cultured cells (in vitro) to (1) identify the cellular sensors of dsRNA, (2) elucidate of the role of candidate honey bee antiviral defense genes, and (3) examine of the interactions between immune pathways and the mechanistic details dsRNA-mediated responses. These experiments will significantly advance the understanding of the honey bee antiviral defense network and enhance our understanding of viral pathogenicity.