Protein nutrition governs within-host race of honey bee pathogens

Manuel Tritschler,Nor Chejanovsky,Jutta J Vollmann,Orlando Yañez,Karl Crailsheim,Peter Neumann

doi:10.1038/s41598-017-15358-w

Abstract

Multiple infections are common in honey bees, Apis mellifera, but the possible role of nutrition in this regard is poorly understood. Microsporidian infections, which are promoted by protein-fed, can negatively correlate with virus infections, but the role of protein nutrition for the microsporidian-virus interface is unknown. Here, we challenged naturally deformed wing virus - B (DWV-B) infected adult honey bee workers fed with or without pollen ( = protein) in hoarding cages, with the microsporidian Nosema ceranae. Bee mortality was recorded for 14 days and N. ceranae spore loads and DWV-B titers were quantified. Amongst the groups inoculated with N. ceranae, more spores were counted in protein-fed bees. However, N. ceranae infected bees without protein-diet had reduced longevity compared to all other groups. N. ceranae infection had no effect on protein-fed bee’s longevity, whereas bees supplied only with sugar-water showed reduced survival. Our data also support that protein-feeding can have a significant negative impact on virus infections in insects. The negative correlation between N. ceranae spore loads and DWV-B titers was stronger expressed in protein-fed hosts. Proteins not only enhance survival of infected hosts, but also significantly shape the microsporidian-virus interface, probably due to increased spore production and enhanced host immunity.

Highlights

Host nutrition can play a key role for the outcome of pathogen infections in humans and animals[1], since it is critical for immune-defense and resistance to pathogens[2]
Feeding protein to honey bee, Apis mellifera, workers infected with microsporidian endoparasites, Nosema apis, resulted in increased spore development, and improved the longevity of infected hosts[7]
The virus strain-specific PCR36 showed that only deformed wing virus - B (DWV-B) was infesting the experimental bees

Summary

Introduction

Host nutrition can play a key role for the outcome of pathogen infections in humans and animals[1], since it is critical for immune-defense and resistance to pathogens[2]. Since hosts infected by more than one pathogen are common, pathogen-pathogen interactions require more attention[10,11,12,13] This is especially true for managed honey bees, A. mellifera, which are exposed to a long list of pathogens, which can act as drivers for colony losses especially in areas with established ectoparasitic mite, Varroa destructor, populations[14,15]. The actual outcome of such multiple infections depends on the nature of interactions between the pathogens in one host. These parasite-parasite interactions in infected individual honey bee hosts can potentially range from competition to cooperation[17,18,19,20,21,22]

Methods

Results

Conclusion