The Gut Microbiota Can Provide Viral Tolerance in the Honey Bee

Abstract

Adult honey bees host a remarkably consistent gut microbial community that is thought to benefit host health and provide protection against parasites and pathogens. Currently, however, we lack experimental evidence for the causal role of the gut microbiota in protecting the Western honey bees (Apis mellifera) against their viral pathogens. Here we set out to fill this knowledge gap by investigating how the gut microbiota modulates the virulence of a major honey bee viral pathogen, deformed wing virus (DWV). We found that, upon oral virus exposure, honey bee survival was significantly increased in bees with an experimentally established normal gut microbiota compared to control bees with a perturbed (dysbiotic) gut microbiota. Interestingly, viral titers were similar in bees with normal gut microbiota and dysbiotic bees, pointing to higher viral tolerance in bees with normal gut microbiota. Taken together, our results provide evidence for a positive role of the gut microbiota for honey bee fitness upon viral infection. We hypothesize that environmental stressors altering honey bee gut microbiota composition, e.g., antibiotics in beekeeping or pesticides in modern agriculture, could interact synergistically with pathogens, leading to negative effects on honey bee health and the epidemiology and impact of their viruses.

Vairimorpha (Nosema) ceranae Infection Alters Honey Bee Microbiota Composition and Sustains the Survival of Adult Honey Bees

“…This study demonstrated that enhancing indigenous gut microbiota may decrease mortality but not control the pathogen, and somewhat similar results have been reported in a field trial [ 61 ]. In addition to nosema disease, other non-bacterial gut pathogens, i.e., trypanosomatids and DWV, also reported somewhat counter-intuitive results [ 38 , 70 ]. These pathogens seemed not affected by adding indigenous gut microbes, and the host mortalities were decreased.…”

Intra-Colonial Viral Infections in Western Honey Bees (Apis Mellifera)

“…Thus, it is possible that the different levels of the two DWV variants observed were caused by venereal transmission, i.e., from differentially infected drones to their offspring. Additionally, differences in DWV genome copies may have also resulted from interactions with other microorganisms, such as pathogens [ 53 , 54 ] or the host’s gut microbiota [ 55 ]. Finally, differential resilience towards virus infection exhibited by the pupae subfamilies could explain these results [ 56 , 57 ].…”

Bumblebees with the socially transmitted microbiome: A novel model organism for gut microbiota research

“…Gut microbiota often help the host to defend against various pathogens (Lozupone et al ., 2012). In honeybees, gut microbiota confers viral tolerance, which means that normal gut microbiota can promote the fitness of DWV‐infected hosts without control of viral loads (Dosch et al ., 2021). More efforts should be devoted to further understanding the protective role of bumblebee gut microbiota against viral pathogens.…”