Activating honey bee immunity with a larval vaccine against Nosema ceranae

Nosema ceranae is a microsporidian parasite that causes a common and global honey bee disease, nosemosis. Nosema weakens honey bees and is associated with other factors that contribute to poor honey bee health. Nosemosis can be treated with the antibiotic fumagillin, but finding a treatment that bolsters the natural bee immune system would be beneficial. Nosema was thought to only infect Apis mellifera adults. However, recent evidence shows that A. mellifera larvae can be infected by N. ceranae. This led us to ask if larvae vaccinated against Nosema would show greater resistance when deliberately infected with live Nosema spores as adults. We show that the Nosema vaccine significantly decreased the level of infection as compared to un-vaccinated controls. Furthermore, in uninfected bees, immune genes associated with Nosema infection were upregulated in bees given the vaccine, but not in control bees. Thus vaccination may be an effective treatment against Nosema. Our results also suggest a new approach: vaccinations may provide protection against a broad range of bee diseases.